In 2015, the Large Hadron Collider (LHC) achieved a milestone, operating at the highest energy ever used by an accelerator experiment. In this podcast, particle physicist James Beacham discusses what we’ve learned about gravitons, Higgs bosons, dark matter, and what’s next for the LHC.
This lecture took place at the Hayden Planetarium on February 6, 2017.
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Frontiers Lecture: Gravitons, Exotic Higgs Bosons, or Nothing At All - Transcript
Narrator:
You're listening to Public Programs at the American Museum of Natural History. In 2015, the Large Hadron Collider (LHC) achieved a milestone, operating at the highest energy ever used by an accelerator experiment. In this podcast, particle physicist James Beacham discusses what we've learned about gravitons, Higgs bosons, dark matter, and what's next for the LHC.
This lecture took place at the Hayden Planetarium, on February 6, 2017.
James Beacham (Postdoctoral Researcher, ATLAS Experiment Group, The Ohio State University):
The title of this thing, as you can see is, "Gravitons, Exotic Higgs Bosons or Nothing All." The subtitle, of course, is "The Large Hadron Collider's First Year at 13 TeV." That's important because this first year at this highest energy ever is extremely important in a lot of different ways. I have a few notes here and I want to tell you basically about what's going on at the LHC, why it connects up with things like astronomy and why you're even here to begin with.
But first thing I want to tell you is that I grew up in southern Utah. This is the home of red and black rocks and clear skies and very nice, hot summer evenings. That's perfect conditions for stargazing. I remember one time. I was a little kid and I had biked with a friend of mine to some distant hill away from the nearest town so we could get up and we could look at the stars. We were sitting on some big flat rock in this beautiful smoldering August night and probably eating gummy worms or something like that.
We were looking up. We were too young to have a decent telescope at that point, but I was sort of a library guy, so I had read quite a bit about astronomy and stars and how planets formed and things like that. I was kind of a know-it-all kid. I'm like, "Look at that up there. Isn't that amazing? Like that star, Vega, it's like the one that's right above you. That star is so far away. It's like 140 trillion miles away. The light that has been coming, the traveling to come into our eyes has been traveling for something like 25 or 30 years to actually get here. Isn't that crazy?"
My friend said, "No, that's not true. It's only like a mile away." I stopped and I was like—I'm a little kid. I didn't want to be a jerk to my friend. I was like, "I don't think that's true because I read in the book that..." and he said, "No. My dad said it was a mile away." I'm like, "Well. I've got to tell you that doesn't make any sense." He's like, "No, no. It's a mile away." I'm like, "No, hold on. This doesn't make any sense because if that was only a mile away, we biked five miles out of town to get here, okay?" I guess I was sort of an obnoxious little kid because I'm like, "Look. If that was only one mile away and we biked five miles," and I drew him a little triangle and I said, "Listen. If we biked five miles out here, the position of Vega would totally change from where we are based on where we started." He still said, "I don't believe you."
I said, "Believe? Belief has nothing to do with it. We can test it." Right then, I told him. I said, "Let's go. Let's do it." So, we got on our bikes and we went back and we were keeping track of Vega the entire time. Once we got back there, I said, "Look, it's basically the exact same space. It's not down here now. It's not over there. It has to be way farther away than one mile."
He stopped. My friend was like looking down. He's like, "But what do I tell my dad?" I'm like, "You don't have to tell him anything. You can do the same experiment with him. Everyone can do this. Everyone is basically at heart a scientist. If you've ever been curious about something like that and you ever wanted to answer a question by performing an experiment, by doing a test, you are basically a scientist." Apparently, I never got over this idea of being the guy who wanted to answer basic questions and design experiments to answer them because I am extremely lucky to come here as the emissary for the largest experiment ever mounted, which is the Large Hadron Collider.
I'm extremely pleased to be here at the American Museum of Natural History as an emissary of this biggest science experiment ever mounted. I come here at a singular moment in the history of science, in the history of physics itself because we have just now, in 2015 and 2016, made a leap forward in human history and the history of our species with respect to science. We have just taken a leap into the unknown and there are no guarantees of what we're going to find. We have just achieved the highest energy in a collider experiment that anyone's ever used and that's 13 trillion electron volts.
I'm here basically to share with you a bit of the excitement of what it's been like to be, like the inside scoop, to be like the boots on the ground guy that's been there in the middle of this ramp-up to the highest energy ever because—at the end of this talk, I would really like you to come away with three messages.
The first one is we have just now entered, in 2016, a new era of particle physics at the LHC and why that means something to you. Hopefully, it will mean something at the end. Number two, whatever we find when we are looking for whatever we're looking for in this experiment is going to be revolutionary even if we don't find anything and the third one is that you are all particle physicists. Yes, that's great, but how can that be true, you may ask, because particle physics, like I said with the first little story, particle physics is what happens when you codify and control curiosity and take it to its logical extremes. The particle physicist is the curious little kid who can't stop asking why and how and what's below. How does this work? What's the lowest thing? What's the smallest thing we can get to?
For example, when you're staring up at the night sky like this, this famous image here, a lot of people, they look at the night sky and they say, "Oh, it's mostly empty stuff," but the physicist looks at the night sky and says, "I wonder if that empty spot is really empty?"
This famous image, as hopefully you know as astronomy people, this is the Hubble Deep Field. This is where my astrophysics colleagues took their telescopes and trained it on a piece of the sky that was basically like the size of like a grain of sand held at arm's length. It was thought to be empty and they let their telescope sit there for a very long time, slowly over weeks and weeks, building up photons, collecting photons. It revealed itself to be completely filled with galaxies and stars and just so much structure that you could not have seen unless you were patient, unless you were able to collect enough data to show that there was something worthwhile there.
I am not an astrophysicist, but I am a particle physicist. With particle physics, we are, in a sense, looking backward in time just like they are looking backward in time when the astrophysicist is collecting these photons that have been traveling for billions of years to get to them.
But instead of inspecting the largest thing ever, we are inspecting the smallest things. We're inspecting particles. Instead of having like a big image of stars and things like that, instead we get 3D photos of things like this. What this is, this is an image from a particle collision that we performed at the LHC. You'll see a lot of images like this throughout the talk, but this is one of the big experiments called ATLAS. It's the one that I work on. It's basically a big tin can tipped on its side filled with a bunch of complicated electronics and it's about six stories high and it's 100 meters underground.
What happens is these two pink things are where the particle beam comes in, the proton beam, and right in the middle is where something that hopefully quantum field theory magic took place. Possibly some new particle happened or was created or something happened and then, all the stuff you're seeing is basically—this is a very unique event and it's called a 10-jet event. That's rare. We don't see very many of those. It could be a smoking gun of something new, something new physics, some new particle that we haven't seen before.
But to do this, to look at these smallest possible things in nature, you might think that instead of a telescope, like my astrophysics colleagues, we need to use a microscope, right? Well, we do, but we also need to go to the Femto scale level. Our FemtoScope is the thing we use and it's actually quite large. How large is large? It's the Large Hadron Collider.
This is what it looks like in the tunnel, down in the tunnel. How big is the tunnel? It's 27 kilometers around and it's a circular tunnel 100 meters under the ground on the border of France and Switzerland there. There are a few experiments along the ring there as you go. It's this 27-kilometer tunnel and it's basically the culmination of decades of work by thousands of physicists from around the globe.
Here's what it would look like around lower Manhattan. I hesitate to make a joke about the 2nd Avenue subway because if we tried to build a tunnel like this 100 meters underground here, I'm not sure—I don't think it'd be efficient for science because if it took 100 years to make the 2nd Avenue subway, I don't know. I don't think physicists would wait that long for that. But this is what it would look like, just to give you a sense of the scale of the thing that we're talking about.
This is just to give you a sense of the scale for those blue tubes, as well. This is me, single-handedly controlling the entire Large Hadron Collider by myself—no. This is just to give you a sense of the scale, but it's also to give you a sense of the extremes that we have to go to probe these smallest-possible energy—or as large as possible energy scale, smallest possible spatial scales to see if we can find new particles because this is what we call a magnet testing center. These magnets are hooked up to these little cryogenic modules where you test these magnets to see if they can withstand the extreme conditions that we need to put them through to be able to even perform this experiment to begin with.
How extreme is extreme? These magnets, instead, in fact, have to be colder than outer space. Outer space is 2.7 Kelvin. We beat that. We have to get the magnets inside these tubes down below outer space temperature, down to at least 1.9 Kelvin. That's the only temperature at which the magnets will have a special quality called super-conductivity which allows them to operate without resistance. That's the only thing that allows us to accelerate the particles that we put in this little beam in the ring up to this highest energy ever because the particles we accelerate are called protons.
You should know protons because you're made out of them, but protons are, in fact, big hulking beasts and they hate to bend. You might think that they're extremely small and it's not so hard to do that, but they hate that and 27 kilometers, you go back to the slide with the tunnel. It seems basically straight. How hard can it be to get these protons to bend? Extremely hard if you want them to go at almost the speed of light, something like 99.9999% of the speed of light.
As you know from some physics, the closer you get to the speed of light, the harder it is to even get you to go a little bit farther. This goes exponential. When you're trying to speed a particle up to almost the speed of light, to get it to go that almost-almost, it's like exponentially harder to do, so we have a 27-kilometer tunnel. That seems great, but it's actually quite difficult to get these protons to bend at this energy that we want to go. High energy is important because—I'm sorry. That's why we have to get these to lower than the temperature that's in outer space. We do that with liquid helium, by the way.
What does it look like in practice? You don't just flip a switch and go to the highest energy ever in a collider physics experiment. You go in stages. First, you put the protons into a smaller ring to get up to a certain maximum speed in the ring. Kick them into a slightly larger ring, get them to a maximum speed there. Kick them into a slightly larger ring, they get to an even higher speed and then, finally into the full Large Hadron Collider, the 27 kilometers.
Then, we're going to dive down inside. This is what it looks like inside the collider. We're going to do sort of a Star Wars thing where we dip down into the—[those are the border there 19:24] for a second. Now we've got a proton. As you know, a proton is not a point particle. It's actually composed of three quarks that are held together in a bound state, but it accelerates farther and farther. It gets almost to the speed of light and then, at some point, you have to—at a few points on the ring—we bend these two beams into each other and we make a collision happen, hopefully make a collision happen. It's actually quite difficult to do.
But if it happens, it'll look something like this. What this is, right at that little point there, with any luck, something interesting may have happened. You might have created a new particle that lived for a tiny fraction of a second before splitting into other particles that then hit our detector. Then, what happens is all those lines come out. We detect those—for instance, the charged particles go through the pieces of the electronics, blip, blip, blip, blip. They leave a little track and then, we work backwards and we try to figure out what those could have come from.
That's basically what we're doing and we basically do detective work. We collect a large number of these collisions and then, we sift through them to try to sort the ones out that are the boring ones that we don't want, that we've seen a million times before and what the interesting ones might be. You might see some more images like this. This is another version of that first one that I showed you with the kind of crazy-looking science fiction stuff coming out, but this is basically the cross-section of the ATLAS detector where you are looking directly down the beam pipe. The proton beam would come that way. Another one would come the other direction. Something happens, a collision, and then, stuff hits our detector. This is another slice from the other side of the tin can.
When we're actually running, you can go to this URL and you can watch live collisions coming off the detector. You cannot watch every single one of the live collisions and that's actually a very key point here. But before we get to that, it's not actually me in that room running the Large Hadron Collider by myself. This is more like what it looks like for our actual work because we are mostly coders and data analysts at the LHC.
This is typically what happens, is that my colleagues and I will sit around and argue about data analysis. We'll make some visualizations and we'll say, "Oh, well, that's not interesting. Let's do it this way." We're basically trying to sort through a huge data set to try to find tiny indications that there may be some new particle that we've never seen before that could be evidence of some physical effect that would help explain, hopefully explain, one of these unanswered questions of physics.
We have a lot of tools at our disposal. It also looks something like this. In the control room, we have these great visualizations here, but this is really just to emphasize that it's not a one-person project. I know that that sounds somewhat obvious to say, but I can't emphasize that enough. The LHC is a truly world collaboration. It is one of the best examples of what humanity can do when it comes together, when it brings people from all cultures all together.
This diversity makes me a better physicist. It makes science better and it's amazing how many times I'll be sitting in a meeting with somebody from South Africa and Germany and France and Columbia and somebody from Canada and somebody from Morocco and Japan and we're discussing ideas. Somebody will come up with some new idea with the thing that we're working on and I'm thinking, "Oh, I didn't even think of it that way." It totally makes our science better. It's an amazing example.
It seems like, in a way, we're cherry-picking a lot of the most curious minds from around the world. But it's because the thing that we're asking, the questions we're trying to answer, they seem a little bit complicated, but they're actually not that complicated. They get to the thing that so many of us have had as little kids and all throughout our lives, like the story that I told at the beginning about curiosity because basically all the research that we do comes down to a bagel.
Take a bagel. I'm not sure if this is Marie's [inaudible 23:25] bagel. I'm not sure. But you take a bagel and cut it in half. Cut the half in half. Cut that half in half. Keep going. How far can you go? Get to like a crumb. You can cut the crumb. How far can you go? You get a molecule. Can you cut a molecule? Yes. You can separate it into atoms. How about can you cut an atom? I see some heads nodding yes. Of course, you can cut an atom. We know that because it's a nucleus with some electrons going around it in some complicated pattern.
In a sense, you can cut that. You can separate the electron. You can get like a proton in the middle. Can you cut an electron? As far as we know, no. That is a point particle. There's no spatial extent there. What about a proton? You saw from the animation already, yes, in a sense you can cut it. In another sense, you can't. If you know anything about the strong force, it's called QCD. It's the notion of cutting becomes difficult here.
But we know that there is some stuff down inside a proton, but can you cut one of these quarks that's inside there? As far as we know, no. That's the history of particle physics. That's what we're doing. That's the curiosity. We're wondering what's the farthest we can possibly go. If you know anything about string theory, you know that's another version of people thinking, "What's another step down below particles? Is there an extra level of structure below there?"
But as you go through the history—just to give you a quick aside with one slide of the entire history of the 20th century of particle physics. I'm sure it'll be completely comprehensive. This is really just what people have been doing. They've been asking this question, making observations. Somebody comes up with a theoretical idea and these things played together throughout the 20th century and this wonderful interplay eventually led to something called the Standard Model of particle physics.
It started back in the 1890s where Thompson discovered that there was something called the electron that you could actually pinpoint. You could figure out its properties. Then, in 1919, the proton was discovered, which was more or less thought to be the opposite of the electron at the time because of the opposite charges that they had. Neutron came pretty soon afterwards and then, the muon came out of nowhere and it was a heavier cousin of the electron. It had a higher mass than the electron and people were like, "Why does this exist?"
Then, that came out of nowhere. Then, people discovered that there were neutrinos, these completely ghost-like particles that don't carry charge at all and they thought were to be mass-less, but they still totally came out of experiments. That was very mysterious. Then, this was the point at which in the 60's we discovered that partons were real. Partons is the stuff that's down inside the protons and the neutrons. At first, people didn't believe necessarily that was like an actual physical effect.
But then, finally we discovered something called the charm quark in this J/Psi things and they called it the November Revolution in 1974, which totally made everyone take seriously the notion that quarks were real, not just a mathematical construct. There was actually a physical effect of this mathematical thing.
That was basically almost in a sense, you could say that 1974 was the year that everything broke in particle physics because people were like, "Oh, I don't know about these. Eh, the way that everything's working together," and then, pow. Everybody knew that quarks were real; quarks and gluons actually worked the way they did and that was the point at which all the standard models sort of came together. I'll talk about the Standard Model in a second here because it's very important for the entirety of our program at the LHC.
Then, you got the tau lepton, an even heavier cousin of the muon and then, you've got the gluon, that came to be a real thing and here's this great photo. If you can see this here, you don't have to work too hard to convince somebody that that's a big bump on your graph into something kind real. Then, the W and the Z bosons came out of nowhere. Well, not out of nowhere. They were fantastically predicted and then, they were discovered. Then, finally the top quark was discovered. That was the heaviest possible quark that we could find and the heaviest fundamental particle that we know of right now.
Then, as you probably have heard of, who in the room has heard of this thing called the Higgs boson? Anybody? Yeah, that's good. This was discovered by my colleagues and I in 2012. Just a brief aside. I have to do this. Martin Perl was one of the guys was basically in charge of the team that discovered the tau lepton. One of his students was named Sam King. Sam King was on one of the teams that discovered the J/Psi. One of King's students is a woman named Sau Lan Wu. She was one of the discoverers of the gluon. Sau Lan also works on ATLAS with me right now and also one of her students was named Kyle Cranmer, who was one of the editors of the Higgs boson observation paper. Kyle Cranmer was my advisor, so I don't know what means for me. Probably best not to think about it, but just to show that this history is really rich.
We finally made it to the Higgs boson. All of this wonderful interplay between theory and experiment in the 20th century finally led to this thing called the Standard Model of particle physics. It's not just—you saw some of these particles that were on the list before and they're now here in a diagram form. It doesn't really mean anything, but it's a nice way to put it on a diagram. When you're cutting things, when you're actually asking, "What's the smallest I can go? How can I cut? What does it mean to cut something?" you're not just making a list of the matter particles you find. You're also investigating how the particles interact, so you don't just understand that there are specific particles that exist and make a list of them.
You're making a list of the forces and the ways that they interact because you can't just have like an electron and a positron just sit there. They actually have to interact in some ways. This is a force. You know what forces are. At the particle physics level, with quantum field theory, forces are interpreted in the way that they are actually exchanges of a different type of particle, so-called vector gauge boson, or a force-carrying particle.
In this diagram, the matter particles are more or less on the outside and the force-carrying particles are on the inside. You have, for instance, the photon, which is the force-carrying particle of electromagnetism. I'll talk about the other ones some more. This wonderful interplay between the theory and experiment led us to the Standard Model and the last remaining piece of the Standard Model was the Higgs boson. I'll talk a little bit more about the Higgs boson later, but that was the one that we finally discovered in 2012. People had been looking at it for like 30 or 40 years. Finally was discovered. Breakthrough of the year and then, it led to a Nobel prize for a couple of the people that had predicted it back in the 60's.
But that final piece that was plugged in, which was the Higgs boson, can't possibly be the end of the story because we know that the Standard Model for all its successes and the Standard Model is—okay, I'm totally biased—but by my measure, the greatest achievement of humankind, the greatest intellectual achievement, the greatest intellectual achievement because it's not just some crazy idea that somebody like came up with and it was kind of more or less true and it's roughly true to some huge error bar. No. It was an amazing interplay of a lot of different ideas that we weren't sure if they were true or not through the 20th century. But they predicted more or less impossible-to-miss things. Basically, extremely good predictions that made it totally falsifiable or something that we backed up with data.
For instance, this thing with the W and the Z bosons. There was a theory that was postulated back in the 70s where it was like they said, "Okay. If this is true, if this thing called the electroweak force, then you should be able to perform X experiment and should find the W and Z bosons at roughly this mass scale." People were like, "That's a pretty precise prediction." We went out and did it and god damn, they were there. It was amazing and at roughly the place they were predicted to be and they had behaved, even with extra experiments throughout the years, almost precisely the way that the Standard Model predicted them to behave. This was all basically just me patting my colleagues on the back for what they did, but it's an alarmingly successful theory.
But it can't possibly be the full story because we know that for all successes, it's incomplete. It's a great theory, but it's incomplete. There are many, many observations from other parts of physics that don't play well with the Standard Model. Those are some of the ones that I'm going to talk about here.
Even though we found the Higgs boson, we don't know what else is beyond there because could it be things like neutralinos. Could it be things like gravitons? Could it be charged Higgs bosons? Could there be extra Z bosons? These things don't even mean anything to you, but we'll get to them in a second.
This is what we do at the LHC. We have to go farther. We have to go to the farther extremes to see if there are new particles that we have not yet discovered that could help explain some of these observations that we don't—that we can't explain at the moment.
What does it mean to go to extremes? Because the Higgs was discovered in 2012 and that was at the LHC, but it was at a center of mass energy of something called 8 TeV, eight trillion electron volts, seven and eight. That was great. We discovered the Higgs. It's a five sigma discovery. We know for sure that there's a particle that more or less behaves like the Higgs boson right at this mass. Okay. But in 2015, we jumped up in energy. We went from 8 TeV to 13 TeV, trillion electron volts.
The Higgs was our last, basically ace in the hole for particle physics. This is the last prediction that we really had that was like a concrete prediction. There had to be something out there that did the Higgs boson job. Then, we found it and then, whatever comes next is kind of open-ended. We don't really know exactly what there is, so this jump to 13 TeV is a jump into the unknown.
What does it mean to jump into the unknown with respect to a higher energy? It comes back to somebody that we all know and love, Einstein. With Einstein, you remember E=MC2. M is the part that nature controls. Forget about C. It's the speed of light. It's a constant. Don't worry about it.
M is the mass of a particle. Mass for particles is not the same thing as like a massive bouncer at a bar. It's not the same thing. Mass for a particle level is just a property of a particle and nature just puts it there. It's like a tag and it relates to the Higgs field, as some of you might know, but it's the tag that Mother Nature puts there. That's the part that nature controls.
The part that we can control if we're clever enough is the E part. There's an equivalence there. If Mother Nature has a particle M with an M that's so high that we've never designed an experiment with an E high enough to get there, we'll never find it. We'll never have any evidence of it. We have to work really, really hard to get the E up to as high as possible.
The way this has worked out throughout history is, like I already said in some of those slides, you've got the top quark that was discovered with a collider energy. This is the E part, the center of mass energy, which was 2 TeV at Fermilab. Then, at 8 TeV, we discovered the Higgs boson. Then, this jump up in energy, it was almost twice as much at the LHC in 2015. What are we going to find at the LHC at 2015 at 13 TeV? We didn't actually know, but the reason why the TeV scale was interesting to begin with, this TeV, tera electron volts, was that we actually had—it's a good question.
Why the TeV scale? Why do we even have to go up for higher energies? Is it just enough of a reason just because we're crazy and we like to build gigantic machines? One reason the TeV scale was built to begin with was because of the Higgs boson. But that in and of itself was not the only justification for building such a gigantic, extra machine. In fact, we had hints of new physics at the previous collider that was inside this tunnel, so this was the same 27-kilometer ring, but it was something called the LEP, the Large Electron-Positron Collider, that ran in the late 80's up to 2000.
But the highest center of mass energy it got up to was 209 GeV. That's giga, not tera. That's giga. That was much, much smaller, but at that energy, in fact, we started to see some hints of something like the Higgs boson that was supposed to exist around the energy range, or the mass range, of the hundreds of GeVs. We started to see these little dips. You don't need to worry about all the details, but when this dips down, it shows you there might be something new coming, some new particle that might exist. We're seeing these dips down here, dips down here.
We also did a bunch of complicated [fits 35:58] to the other observations and it suggested that there should be a Higgs in this kind of range and it's actually kind of interesting because this yellow is right where the LEP could get. That's the highest possible mass range for the Higgs boson that it could probe, right up to here. This white part was open-ended. Then, the Higgs boson was actually discovered about right here. It was the LEP collider almost, almost was able to discover the Higgs boson.
In fact—I didn't work on that collider, but my advisor and other people did—they always tell these stories about how certain experiments really, really pushing hard to make the collider to go up to higher and higher energies and things started to break. People were like, "We can't do this anymore. We're going to ruin it." They're like, "No, no. I think it's right around the corner." They didn't have any reason—they didn't have any evidence for this, but they started to see some little blips.
The hints were at LEP, but then we finally discovered the Higgs at the LHC in this jump to 7-8 TeV, but we knew that there had to be new physics at this TeV scale. Knowing—when we say that we knew that there must be physics at the TeV scale, we had good reason to believe this from a lot of different other observations and also, some things with respect to supersymmetry, which you may have heard of.
But more or less, this jump from 7 and 8 TeV up to 13 TeV was a jump into uncharted territory. Uncharted territory means that all the particles that I showed you on that wheel, on that Standard Model wheel, the strange thing about them is that there's really only like three on that list, on that wheel, that exist in and around you right now. There's basically only three of them, the up and down quark and the electron. The rest of them don't really hang around in abundance right now because they only exist in abundance a tiny fraction of a second after the Big Bang because when we are going to higher and higher energies, we're actually going back farther and farther in time, as well.
That's why there's a very deep connection between what astrophysicists do and what particle physicists do. Astrophysicists are letting their telescopes sit and collect photons that have been traveling for billions of years to look at what the universe looked like a long time ago. We're trying to recreate the conditions. We're like the crazy little kid, it's that we just like break things. We are trying to recreate the conditions of the universe just a fraction of a second after the Big Bang because if you go back—if you go to now, the universe is basically at a very low average energy. You can see a nuclear family here. This must be the 50s or something. Then, you go back farther and farther and you get to about two minutes after the Big Bang and this is where things like nuclei started to form.
One second after the Big Bang, you've got things like where quarks started to be bound into states like protons and neutrons. But then, if you go back to a fraction of a second, even push it back farther and farther, you then get to the place where some of these particles were hanging out in abundance, like Z and the W and the gluon and things like this. We have to go farther and farther back to see if we can find particles that we've not discovered yet.
This is where the Large Hadron Collider can get. It can get to about to—I forget exactly where we're probing out there. It's less than a second, but we can't possibly get to the [point 39:09] scale, as Mordecai said. But what we're doing, the reason why we need high energy should be clear now. We need to get the high energy to hopefully find a new particle with some M that we've never seen before.
But what about this other part where we actually have to analyze the data? Well, discovering a new particle is actually a simple, three-step process. You, number one, accelerate protons to high energy. Two, collect a lot of data. Then three, you look for an excess above what you're expecting.
This is, on the left, you see a plot of the, it's called Integrated Luminosity over the year of 2012, when the Higgs boson was discovered. What it is basically you're starting—this is the day in 2012. You start from the beginning of the year. You get more and more data, more and more data and eventually, you get to the very top and you've got a ton of data. Basically, this is called Total Integrated Luminosity. It's just a measure of how much data you're getting.
Only with the data that we were able to take up to that black line, that was enough for us to say the plot on the right was the Higgs boson discovery. So, this plot on the right, the red line, the background line, this like dotted line, that's what you should expect to see if there's no new particle there. Your data will look like this. You [bin 40:23] things up and these black lines should follow the red dotted line.
Then, you get this tiny little bump. There's a deviation from what you're expecting and if that bump gets prominent enough and the error bars on these black dots, there's actually error bars on those black dots up there. They're just so small because we took enough data to indicate that this little bump was a new particle and not just some fluctuation. That was enough to discover the Higgs boson.
But the problem with determining that you've found something new, it's really, really difficult because the LHC actually gives us too much data. What a collision looks like at the LHC is like this. The beams were coming in the two different sides, like I said and at some point, you have to cross the beams and you have to make this collision happen. It's not so much that you're actually—it's not like one proton that you do. You don't actually take one proton and one proton and send them in front of each other.
It's more like you take two big pancakes of protons and smack them into each other because you've got Lorentz contraction that happens. It's going almost the speed of light. Each one of these pancakes, in fact, contains about 10 to the 11 protons. Then, the LHC crosses these bunches 40 million times a second. Each one of the bunches of 10 to the 11, 40 million times a second, the maximum event rate in the ATLAS detector—it's this big six-story high cylinder filled with complicated electronics is basically taking a three-dimensional photo of each one of these collisions 40 million times a second.
We can't keep all of those. We literally cannot keep all of this data. We can only keep about one kilohertz of data. That's sad because we're losing a bunch of data. That should make you cry and it makes all of us cry. Okay, not so much, but it gets even worse, though, because it's not just the amount of data that we have to cut down to get to something that we can even write to tape. It's that the average number of collisions per bunch crossing is almost 25. This is small potatoes compared to what we have to deal with. This is a bunch of different collisions that happen in one bunch crossing.
If you've got 10 to the 11 protons and they're passing through each other, they mostly just pass through. Only 25 of them actually will collide. It's crazy. The rest just kind of pass on through and then, we use them again for another collision, but this is all calculated beforehand to optimize our ability to find new particles and then, the average number of usable collisions of those is only about one. Then, the ATLAS is basically a 100-megapixel camera. The size of a raw event is a few megabytes and then, the total LHC data for years is something about 50 petabytes. This is the amount of data that we have to deal with.
What we can do, though, is we do clever things like this. We start with one of these collisions where there's something like 25 of these little dots here; 25 collisions that happen in one bunch crossing. Then, we do some—we apply some criteria on the tracks and eventually, we get down to the four tracks that may have come from a Higgs boson that came to four leptons. This is the stuff that we can do. We can do it. We do it all algorithmically, but it's quite difficult to do. The conditions are hard.
Forget about the plot for a second. We discard something like 99.998% of our data. Once again, that should make you cry. It makes me cry, but the reason we can do this—I'm going to skip this just for the sake of time—but basically at the end-of-the-day, we have something like 16 petabytes that we collected in 2016 for the ATLAS detector itself.
The reason we have to collect all this data, the reason why we have to have so much data, so many collisions, 40 million per second down to 1,000 per second that we keep and then, if you run the collider for like all year and collect all the data, then that gives you a huge number of collisions, on the quadrillions of collisions level that you've performed, the reason we're doing that is because the particle processes that we're looking for are not just at higher energies.
The mass of the particle is not just maybe at the higher E, the higher M and the higher E. It's also extremely rare. The process is extremely rare and to explain what I mean by rare, you have to know a little bit of quantum field there, but it's okay because physicists are visual thinkers, as well as mathematical people. We did have to do six years' worth of graduate school, but not all of that was calculating quantum field theory calculations.
We also think in terms of diagrams. This is something called a Feynman diagram. It's a very nice way of visualizing a particle collision. Space is on the Y axis. Time is on the X axis, so at some point in time, these two particles are far apart in space. They get close together and then, something happens and a new particle is created. Then, that particle will then split into other particles. Time has gone on. You have two particles that cease to exist and create a new particle and then, split into other particles, which hopefully hit our detector because for quantum field theory for particles, the collisions are not the same thing as car collisions.
For here, they have different rules, obviously. Imagine instead here you have two cars. Imagine a car collision where the two cars vanish upon impact. A bicycle appears in their place and then, that bicycle explodes into two skateboards, which hit our detector. The reason we can do that is because the things that we're caring about at the particle level is not just the names of the particles and the number of particles that exist. Instead, the things you care about are the conserved quantities. We care about the physics quantities that are conserved before and after the collision. As long as you keep track of those, it doesn't matter that you might have had an electron and a positron that annihilated and a Z boson created and then, is split into a muon and U+ and a U-. You can do this.
The cool thing about these diagrams is that they're actually mathematical tools. If I can write it down, if I can draw a diagram like this and I have shown that I have satisfied all the criteria of quantum field theory that conserve quantities, that process has to exist. It has to happen because it's physically allowed, so it has to happen. It just might happen with a very, very, very rare frequency.
But this is a precise mathematical framework. Each one of these lines has a little thing that goes over to the equation. I didn't put it here to not bore you, but you basically put all these lines in these vertices into your equation. You turn the quantum mechanical crank and then, it spits out the probability that this collision and this process will happen if you perform this experiment at a certain energy level. This is the mathematical tool that we do.
Sometimes these processes are extremely rare. By extremely, I mean something like this. So, two protons—that's where we use the LHC—these are my cartoon protons. I hope you like them. Something that is very prominent is the Higgs bosons. The Higgs boson, two protons are coming in once again and time goes this way. Then, eventually, they're close enough. They start to feel the strong force encoded in this gluon thing here. Then, forget about the middle part. Then this Higgs existed and then, it decays to two photons. That's something that's going to happen. Photons you know exist because you're being bathed in them right now. We know that photons exist and they're stable. They will hit our detector.
You can calculate this diagram. It tells you that if you make a Higgs boson, you only create about one Higgs boson per billion events. Then, the percentage of the time that Higgs bosons then decays into photons, which we want because we can detect photons, we love photons, is about two per trillion. Contrast that with the no new particle hypothesis. That's the Standard Model. It's just giving you two photons by itself. That happens a thousand times more—that's a thousand times more common, so you're looking for the needle in a haystack of even two photon events which you can pick out. It's not even a needle in a haystack. It's like you're looking for another piece of hay in the haystack that's slightly discolored compared to the other ones. It's buried down in the bottom. It's in the mud.
So, the Higgs boson can give you two photons. Another thing that can give you two photons at the LHC is something called the graviton. I put the questions marks here. It's because we don't know how common this is because we've never discovered a graviton. Clearly, it's much rarer than our experiments currently can probe. Otherwise, we would have seen it by now. That allows you, if you don't see a new particle that you think might exist, it allows you to put a very strong limit on how often it will be created. That's a lot of what we do at the LHC. That graviton part is perfect example of why things are so exciting right now at the LHC.
It's a perfect segue—patting myself on the back on my segue here—the segue into what it is that we have been doing with the data analysis at the LHC. The reason why I even brought the word graviton in the first place is because the thing that I said earlier, the Standard Model for all its successes, we know it's incomplete. We know that it's not the complete picture of nature as much as we would like it to because let's just list the forces that exist.
We know we've got the strong force. All the forces that we know exist in nature and the strong force is the strongest one we know. I'll give it 100% in terms of strength, one, you can't get higher than that. The strong force is encoded into the Standard Model by this gluon, this G thing. Electromagnetism is 0. 007, double X, apparently James Bond compared to the strong force. It's much weaker compared to the strong force, but it's still fairly prominent. If you've ever been shocked before, you know that it's prominent.
But the photon is the force-carrying particle of electromagnetism. Then, we know there's something called the weak force, which you probably know best because it's responsible for nuclear decay, is fairly weak compared to the other ones, but we can still detect it. We know it exists. Because it also has force-carrying particles and it's kind of an oddball because it has two force-carrying particles associated with it, the W and the Z, but we have discovered them. We know it's in the Standard Model.
But what's the one that's missing? Gravity. Gravity is all the way down here. It's 10 to the minus 39 compared to the other forces of nature. It's like it doesn't even exist. It's crazy. We don't even think about it in our calculations at the LHC. But, okay, now we've gone through the process. Where is it in the Standard Model? It's not there. That's crazy. That should bother all of you because the most successful intellectual achievement of humankind, the Standard Model, makes these amazing predictions. We went out and found all the things that it predicted. It doesn't include gravity. That's crazy. We know gravity exists. Look. It's guaranteed that gravity exists. Gravity is not in the Standard Model and that's a disaster.
This is one of the things that we can possibly probe at the LHC. This is a good example of what has been going on for the last couple of years because it segues to something that got into the news a little bit. In 2015, we finally, like I said, we made this jump up in energy from 2012, we discovered the Higgs boson at 8 TeV. Hooray, Higgs boson, champagne, all this. Nobel prizes, blah, blah, blah.
But then in 2015, we jumped into this unknown because there's no more ace in the hole. There's no more Higgs to discover. We already discovered the Higgs. The rest is all these open-ended ideas, supersymmetry, quantum black holes, large extra dimensions. We're jumping into the unknown. It was really, really exciting. A lot of us have been basically waiting our entire lives or careers for this moment.
On June 3, 2015, we all gathered in the ATLAS control room, looking like Norse gods, explorers. We were in the control room waiting for the first stable collisions because these beam guys, the guys that work on the beam, the actual blue tubes with the magnets and the proton beams, they're a different breed of physicist than me. I have to rely upon them to collide the protons correctly inside the middle of our detector and then, I can do my job. Then, the rest of us are sitting here, waiting, waiting, biting our fingernails and waiting for the beams to come through.
Eventually, "We saw collisions. That's the highest energy ever. It was amazing." Applause, champagne, celebration. You can see people applauding here. It's great. We did drink champagne, too. I think it was actually Prosecco, though. I think we had more Italians in the room that day or something. But this was a milestone for history. It was really electric. The mood was fantastic. It was very, very exciting because we had no idea of what we were going to find in this data. It was a jump into the unknown. It was a leap into the unknown.
Then, a few weeks later, we found a bump. What do I mean by bump? It's kind of like that Higgs boson bump that I showed. But this bump was something like this. Once again, you've got this red line and then, you've got some data points that are supposed to follow the red line if there's nothing there. Then, suddenly, they jump off the line. But the one thing to note here is that the error bars on these points are much larger than that Higgs boson one that I showed you. This is not enough for us to say that it was a new particle.
Only after a few months' worth of data taking in 2015 itself, it was a small amount of data. For 13 TeV, you don't just flip a switch and then, hooray, you start taking all the data you can and blah, blah. You go very, very slow. In 2015, we made it slow, like, "Okay. Let's take a little bit of data," and then, sit down and stop for a second and say, "Okay." Is the LHC still operating correctly? Okay, great. Let's keep going. A little bit more. I'll show you. That was the plot that I blew by earlier, but basically, we went very, very slowly in 2015.
Once we knew everything was great in 2015, in 2016, we went way high and cranked the thing up because we could trust it at that point. But for 2015, we saw this tiny little bump and we were like, "Oh, I don't know. What is it?" I spent hours and days and weeks in secret meetings with my colleagues arguing over this little bump here, this bastard. We were poking it and prodding it with our most ruthless experimental sticks to see if it would withstand scrutiny because its significance, we have this very high bar for discovery of a new particle at the LHC, something we call it five sigma. Basically, it means that there's almost no chance that we have made a mistake—or, not a mistake, but there's almost no chance that this is only a fluctuation of nature because you can see, there's some wiggles here back and forth.
There's some wiggles in the other places. Nature fluctuates. Nature, the observation that we made, may fluctuate a little bit. There's a possibility that this little bump was either something new, a new particle, or it was just a fluctuation of the data. But for us, it's not up to us, really. We just have to take enough data until we can finally get to the point where either it turns into a gigantic new discovery or it goes away.
But during this time when it was only in the iffy point, it was a weird time at CERN because the experiments are number one, separate. We have on this ring the ATLAS experiment and the CMS experiment and then, two other ones. But ATLAS and CMS are more or less designed to do the same thing. Both of those discovered the Higgs boson. But we also have to keep them separate so that we can corroborate each other's findings. Not only are we separate from each other, we are also separate from the theoretical people. I love my theorist colleagues, but they can get a little bit—they can be interesting.
They can be a little bit persistent with their questions sometimes, so this is John Ellis. He's a dear colleague of mine down the hallway at CERN. He was one of the original sort of designers, or explorers, of the notion of supersymmetry. I don't think I'll have time to go into it here. But maybe you know a little bit about supersymmetry, but it's a fascinating concept that we're still testing at the LHC. He's one of the preeminent guys in the history of particle physics.
One time, during this whole little bump excess time, I was sitting having coffee with John in the commissary at CERN. He's like, "So, James, what's this I'm hearing about a bump? A bump in your data?" I'm like, "I don't know what you're talking about, John." He's like, "What's this I'm hearing about 700?" because if you go back to this plot, it's around 700-750, this little bump because we talk in terms of mass, once again, this little bump. He's like, "What am I hearing? Something about 700?" I'm like, "John, I can't ethically tell you anything." He said, "Well, what about unethically?" I'm like, "John, you can't do this to me."
Finally, after we were able to do our job and allow us to analyze the data, we made a little announcement in December of 2015. We had this big seminar at CERN. This is not the typical attendance that we get at our seminars at CERN. But this was nicely attended and we made our little announcement of our little bumplet, called an X(750). It was around a two sigma. It's not five sigma at all. Two sigma is enough to make you raise your eyebrow, but it's not enough to make you pop a champagne cork. Basically, we need more data. Our message was very clear.
But once again I said, "This is ATLAS right here. ATLAS, that's my experiment." There's also this other CMS experiment. If ATLAS sees one little bump, people don't really care so much about it. We just keep an eye on it as we take more data. The problem with this announcement is that CMS saw more or less the same thing at the same point, almost exactly the same point. They see this little bump off this. It's another way—this green-yellow band thing is another way of presenting the exact same information that you have over here, but you're seeing it's almost at exactly the same pace.
Even though these two together, there's still not enough to claim a discovery at all. The experiments were being very cool about it. We're like, "Okay, hold on. This is interesting. Let's keep an eye on it as we take more data." We were trying to be extremely cool about it. We failed. The press ran with it anyway. It was all over the news. People are saying, "Ooo, hints of a new particle." The news loved it. They ran with it.
Even better than that, my theorist colleagues—I love my theorist colleagues—they wrote 500 papers interpreting our little bumplet that was not significant at all. It's actually a very interesting thing. We call it a fire drill in this case. They wrote like 500 papers about this. More or less, the world of particle physics had been flipped on its head and to understand why this was the case, it's not just that both CMS and ATLAS saw something in about the same place because we see fluctuations come and go in our field and they're more or less—sometimes can be in the same places. Sometimes they're not.
It was also very suggestive because of the type of excess that this was, the type of new particle excess, the channel that it came from because you have two particles that come in. Something happens and then, a bunch of particles hit your detector. Those bunch of particles could be any number of things. I have a diagram I'll show you in a bit, but very rarely are the ones that I was using earlier, where you see only events that have two photons in them. That's extremely rare and basically nothing else because there's a lot of other stuff that can hit your detector. If it's basically nothing and two photons, bing, bing, that's rare, so you really keep those events. You sift through them to see if it's something new.
The reason why two-photon events are unique is because this is—see this guy here. He's the lucky guy that got to stand there as they're bringing in the rest of these electronics in the middle of the detector. Hopefully it didn't crush him or something. But this middle part is the stuff that is more or less devoted to almost only—like the tiny ring in the middle is only devoted to photons and then, around here is something called hadrons that will hit our hadronic [collider 60:45] and then, the rest of this volume is devoted to muons.
A huge part of the detector is devoted to a bunch of other particles except for photons. Photons are extremely rare when they show up in our detector and it's only this middle part in here that can actually see the photons. When you see events that only have two photons in them, they're easy to pick out because like I said, there could be electrons in events. There could be neutron jets, proton jets that hit and the muons that go through the entire thing, so two-photon events are extremely rare.
Once again, we can do this because we can pick these two-photon events out of this huge background of other stuff that is there. The reason we do this is algorithmically with both our hardware level and also, with our, we call it an offline trigger level thing, where if you see an event like this, it's just a bunch of crazy crap going everywhere, you toss it out. You never see it again. However, if you see if a very clean-looking event like this where it's just these two yellow blobs that indicate two photons, there's no tracks going through there. Photons are not charged, so they have this charge zero, so they're not going to leave a track behind, so there's no track here plus a blob. Keep that one.
Then, what you do is you take all the events over your entire 2015 that have only two photons in them and you calculate the angles and calculate the energies and then, you work backwards, you do detective work, to calculate the M, the mass, of these two photons, the particles they could have come from, and then, you bin all those up. You put them in a plot. That's all we're doing with this data analysis. That's what we did because two photons are extremely rare.
But it's not just the fact that we've seen two photons. It's the fact that photons have very special quantum properties. What does this have to do with gravity? Let's go back to—okay. Photons, they have this special quantum property of spin where they have a certain spin. There's a theorem that says that only particles that have a certain other type of spin can decay into two photons. That very, very limits the number of new possible particles that could give you two photons. If I have like a big line that is basically old background processes, there's no new particle, but if I see a little bump in my line, if it's only a two-photon line, that limits you down to basically two possibilities that could give you this little bump. But one of those possibilities is gigantic because it has to go back. It has to do with gravity.
Once again, let's go back to the universe. We'll list the forces that exist on here. Gravity is all the way down here. We know that it exists, even though it doesn't play well with the other ones together. Once again, the thing about gravity is that it's extremely weak compared to the other ones, right? We don't know why it's extremely weak compared to the other ones. The thing about how weak it is and how strange that is—because I jumped earlier. I can briefly beat gravity when I jump. I beat gravity there for a small fraction of a second. But I can't possibly pick an individual quark out of my hand. It's a completely different realm there. We have to think. For a long time, people have tried to determine why gravity might be so weak compared to the other forces because if we can't find a particle manifestation of it, then there's no way it'll play well with the other forces.
But a lot of the explanations that people have come up with over the years are actually quite wild. One of them is really fantastically cool. I put all the forces of nature here on this universe slide. Then, to remind you that all these—okay. You and I live in three dimensions of space. I hope that's a non-controversial statement. All of the forces that we know of also live in three dimensions of space because we live in there, too, and we feel all these forces. We can measure them.
And to remind you that you are also stuck in three dimensions of space, I'll put a little grid here. This is the three dimensions of space that are now flattened into two dimensions of space. Then, to remind you that you are also stuck in three dimensions of space, I'll put Beyoncé here because she's a very good example of humanity.
One of the examples, one of the explanations, as to why gravity could possibly be so weak compared to the other forces comes down to the fact that what if gravity actually exists in other spatial dimensions that are invisible to you and me. What if gravity is just as strong as the other forces if you were able to measure it in some extra-spatial dimension and what you and I experience is a tiny slice of gravity, making it seem extremely weak?
That sounds very science fiction-y, but if it's true, we have to modify our Standard Model of particle physics to include a new particle of gravity, because if there's a particle of gravity, if there's a graviton, it has to have some particle manifestation if it's going to play with the other forces well the way we understand these other forces. Then, there would have to be a hyper-dimensional graviton that lives in extra-spatial dimensions, too.
Of course, this is a crazy sounding idea. How are we going to possibly test a multi-dimensional, hyper-dimensional graviton? The way we always do. By slamming together two protons at the highest energy we can possibly get them to and what happens is that the graviton have these special quantum properties that if it were to be created, if you smack reality hard enough, you smack the fabric of space and time hard enough, you might be able to—and just at the right energy that corresponds to the mass of this particle—you might get it to reverberate into any extra-spatial dimensions that exist and then, it would decay.
One of the ways that it would decay would be into two photons because photons have this special quantum property, the spin, that a graviton could give rise to that. The graviton is one of the highly-motivated possible new particles that could give rise to our little, two-photon bump.
So, the possibility of explaining the mysteries of gravity and also of discovering extra-dimensions of space, that's a pretty good explanation as to why thousands of physics geeks collectively lost their marbles over our little bump because it would be a fantastic discovery, it was true. But once again, at the time of us, our little announcement that got in the news, people were like—we in the experiments were like, "Hold on. This is a two sigma evidence. It's not at all a discovery.
We need to take more data," because with more data, the little bump will either turn into a nice, crisp Nobel prize here on the left—so this is the version of as you take more data with the Higgs boson discovery back in 2012. As we took more data, eventually this little bump got more and more significant and finally, it crossed the five sigma threshold and you get a discovery. Great. Or if you take more data, the extra data will fill in the space around the bump and turn it into a smooth line and it doesn't look so smooth, but trust me. Those things are distributed equally and nicely normally around a line. That's not a discovery on the right.
We took more data in 2016. With everyone waiting with bated breath, even we in experiments are like, "Hold on. This is not..." We have to be very sober, somber physicists. Let's take more data, see what happens. Everybody is like, "Ooo, what's going to happen?" We're still getting lots of questions from John Ellis. John Ellis is constantly following me down the hall. "What's next? What's next?"
We took more data and with five times the data, several months later in 2016, our little bump turned into smooth line. Awww. Of course, the news responded the way that they should. "Oh, it's so sad." Hopes fade and sad particle physicists. Given the tone of the coverage, you'd think that we decided just to shut down the LHC and go home.
But that's not at all what we did. The interesting thing about that is it did capture the attention of a lot of people. It captured the attention of the theory community and it captured the attention of the news because people have been so excited about the LHC for such a long time. This was our first look at 13 TeV, this highest energy ever; the first look that we did at it.
But the thing is, like I said, when you jump up to this new E, this new energy, you have the possibility to find new particles with this M that nature put there that you've never seen before. But the other thing is that you sometimes have to wait for a very long time to build up a large amount of data to see if there's a new effect in there. You can't just expect something to immediately show up because new physics, new particles, can show up in different ways.
I guess the analogy I like to use is imagine that you're a space explorer searching for aliens. You're arriving at a distant planet. Your first task is to do what? Your first task is to orbit the planet, land and first look around. Are there any big monsters to jump out at us and big, hulking beasts for us to discover and find? But the thing is, life does not only exist like that. Life also could exist in microbial stuff in the dirt. If you don't see something immediately, big, ugly monsters, you just fly away and go away? No. You'd be a terrible physicist if you did that. You spend the next couple of decades sifting through the sand trying to see if there's something more subtle that exists there.
That's exactly what we do at the LHC because particle physicists are not just crazy kids who are smashing stuff together to see if there's new stuff there. We are explorers in a very literal sense because we have to map out territory. We have to do cartography in a way. We have just opened up this new energy regime at 13 tera electron volts. We took our first look at the data to see if there's any brand-new particles or any monsters, aliens, for us to discover. We can report that there are none. We saw a weird-looking alien blob on a distant mountain, but once we got closer, we saw it was just a rock.
But then the rest of the entire two decades that are in front of us is where the new particles could show up, only if we take a very large amount of data. You have to stick with us for a long time. We'll have some things that are coming and going, but it's only possible that the discoveries will come in many, many years. It's not up to us, but the thing about the two-photon bump that it was a little bit silly is because it was only one bump of many that we're chasing and many that we're keeping a watch on as we take new data. This is the current watch list.
For example, the ATLAS experiment, we see this little bumplet here at about 3 TeV, which comes from this thing called Zh decays, which one of the possible—see, it's 2. 5 sigma. It's even more than the other one. Why aren't there 500 theory papers on this one? One of the explanations for this could be an exotic W prime boson, an extra force-carrying particle. Another one comes from the CMS experiment. They're seeing this little bumplet in photon plus jet events, whatever that is. It's possible that it could be a new quark, so we have to keep an eye on these as we take more data.
Then, the ATLAS experiment also sees this little excess here in this black thing where it dips down. This could possibly be evidence of something called a supersymmetric top squark. We're keeping an eye on that one as we take more data. Great names. If you don't like these names, tell John Ellis. I didn't come up with these names. Another one that we're looking at here is this little bump off the thing that we see for these exotic Higgs boson decays here.
We're keeping an eye on all these things. This is the sort of program that we are doing at the LHC. This is how long it could possibly take for us to find new particles. Something could come up right away. We take more data in 2017. It could turn into a smooth line or it could come into a nice, sharp peak. You'll definitely hear about it if these things happen.
I know I'm going extremely long here. Is it okay if I keep going? Okay, great, because this Higgs boson part, I want to touch upon the Higgs boson before I—I don't think I'll get a chance to get to dark matter, but if anybody's interested, we can talk about it. Oh, okay. Fine, I'll talk about dark matter, too. Let's go. Pow. One more hour, let's do it.
The reason why the exotic Higgs boson—I have to talk about exotic Higgs bosons because it's in the title. It's in the title of the talk. I guess dark matter was also in the little abstract, too. Give me seven minutes. So, exotic Higgs boson decays and the Higgs boson, I could give an entire two-three hour lecture series just on the Higgs boson. But hopefully you've heard of it. Some of you raised your hands.
One thing that you may have heard about with the Higgs boson is that it's responsible for—it seems very mysterious. It's like it's hard to explain. It's even hard to explain sometimes to physicists. But not only was it the last remaining piece of the Standard Model, that's why it's important, but you also sometimes hear it referred to as the particle, the field of that is responsible for giving mass to the other particles.
You see this M part that I talked about, the mass of the particle. Those M's are set, more or less, by the extent to which the particle interacts with this Higgs field. The Higgs field is a very strange field because even though I use the boson for Higgs boson and these other force-carrying particles inside the little ring are also called bosons. Boson is the class of particle. Those force-carrying particles are slightly different. The Higgs boson is not a force because it's not a vector field. If you know some math, you know there's a difference between a scaler and a vector. The scaler is just a number. It doesn't have a direction to it, but a vector is a number and a direction. You have to specify a direction and a coordinate system.
All the forces that we know of, all the fields, the fundamental fields, there's this duality between forces and fields in particle physics. All the fields that we know of are vector fields except for the Higgs boson field, the Higgs field. That's the only scaler field, fundamental scaler field, that we know of that exists in nature. That's crazy. That's why it's very difficult to explain and it's almost like the entire universe is permeated with this Higgs jelly. This jelly and the extent to which a particle interact with that, if it's dragged more by the jelly, then it has a higher mass. If it's not dragged very much at all, or zero, like the photon, has a zero mass.
But it's not just that. There's actually another reason why the Higgs boson has to exist and why something like—either the Higgs boson or something like it—that did its job had to exist prior to 2012, prior to discovery and it has to do with the reason why these W and Z bosons have masses to begin with. We can postulate this Higgs jelly. Something goes through it. If it's dragged by it quite a bit, then it has a bigger mass, but if it's not dragged at all, then it has low mass.
That's sort of an ad hoc thing. It's like, "Oh, great. I just postulated that," but there's other observations that came up with—we found these things called the W and Z bosons and I alluded to the prediction of those things back in the 70s, where it was like, "Okay, if the electro-weak force is true," these guys wrote down the prediction and they're like, "This is where you should find these. You should find a W-plus, W-minus boson plus a Z boson around more than like 30 or 40 GeV." It turned out they were actually higher, at 80 and 90 GeV. But this prediction was quite precise. It actually gave this lower bound and you should go up there and find that.
But the weird thing about that is that makes no sense with respect to the rest of the physics that was going on at the time. The fact that the W and the Z should have big masses, that made no sense because they're force-carrying particles and the other force-carrying particles that we postulated and knew of had zero masses. All the mass of the quantum field theory at the time was like force-carrying particles should be mass-less. But instead, this prediction said, "If you have this other stuff you put in there, these will have large masses and you should go out and find them in the experiment." Then, they were found with these large masses.
Something had to come along to explain why they had such large masses. Back in the 60s, that's where these guys came up with this idea that's something referred to as the Anderson-Brout-Englert-Guralnik-Hagen-Higgs-Kibble-'t Hooft mechanism because as you know, a lot of times, these sort of paradigm shifts, if you're a Thomas Kuhn type of person, these paradigm shifts in science, they don't really come out of nowhere. It's not just one person, lone genius. It's coming from a community; people that came up with the idea at the same time.
That's very true here. I even heard someone once tried to refer to this as an acronym, like the ABEHG mechanism. Typically, Peter Higgs just wins out and we call it the Higgs mechanism. But this Higgs mechanism, they discovered that one way they could explain theoretically and mathematically and physically why the W and Z bosons have masses is if you just postulate this extra Higgs field, this Higgs jelly that exists, and it has this very profound consequence.
The profound consequence is this. You postulate that the entire universe is filled with the Higgs jelly, but it's not just a—you can postulate a random scale or field and it can have zero value everywhere. It doesn't matter. If I put a zero into my equation, if I take my complicated equation plus zero, it doesn't change it.
However, if I postulate that this thing has a non-zero value everywhere in space, that's going to change stuff. This is where I start with—you can't see the little yellow dot there—but for instance, I could postulate some scale or field that has a potential energy that I live at the bottom because there's no reason for me not to live anywhere else. This is zero. If it has an average energy to zero all over the universe, nobody cares. It doesn't change anything.
However, the genius of the Higgs mechanism is that it postulates at some point, just a fraction of a second after the Big Bang, things were extremely hot and things cooled down enough for this Higgs mechanism to kick in where suddenly, this average zero value turned into this Mexican-hat looking potential instead. When you used to be right at the zero mode, that was the most probable place for you to exist because it was the least energy you had—as you know, the universe hates to expend energy and so, just like us watching the Super Bowl. We want to sit on the couch and sit there.
Nature does not like to expend more energy than it has to, but instead, if the potential looks like this because we got to a critical temperature in the universe, that's not the most energetic place to live anymore for the universe. It can't just balance there. It has to choose a direction to go. It has to fall down into this extra dimension that we've created here. This is something called symmetry-breaking.
The history of particle physics is really just the history of the math of it is us identifying symmetries of our equations that correspond to conserved quantities in nature that are either respected by nature or are broken. We call these broken symmetries. If you have a conserved symmetry like charge, we know that charge is conserved.
If you have some other symmetry that can actually be broken, something like for instance, CP, if you've ever heard of something called the CP violation, we know that these things are possible symmetries that you can postulate that nature breaks. These have different consequences. In this case, what it did is it gave you this extra degree of freedom in our math. The place where this little—previously there was nothing going on, suddenly you have a symmetry, a rotational symmetry, that was broken where there's now this extra dimension that costs you no energy to roll around in.
I'll leave it to you to go back, to read some of the field theory about it. What that does is it immediately gives you these extra degrees of freedom that get eaten up. We actually use that term, eaten, by the W and Z bosons. It gives them masses. You crank through the quantum field theory and it gives you the masses of the W and Z, which now naturally have masses just because of this spontaneously broken symmetry and it postulates that there's an extra boson, an extra boson particle for you to discover. That's the Higgs boson.
You get massive W and Z bosons. It explains your problem. It solves your issue and plus, you get this extra Higgs that you're supposed to find. You're supposed to design an experiment to go out and find. That's the spontaneous break in the symmetry. This was the thing that was postulated in the 60s. Then, people took it and ran with it and like, "Oh, this makes so much sense. This is awesome. Let's go with it and let's figure out how this plays in with the other stuff that we understand. Let's see if we can predict some other stuff."
For instance, there's John Ellis again. John, Mary and, I forget Antoniadis' first name, Dimitri, I believe. They wrote this fantastic—but for the longest time, the Higgs was almost kind of an afterthought. It was this great thing. It was like, "Whoa. That solves the problem." More or less, people thought, "Okay. We've solved the problem. We'll find the Higgs boson eventually. Let's move on with some other things." People were interested in talking about supersymmetry and string theory.
But this is a fantastic paper that you can go to the CERN archives and pull out. It was almost so much of an afterthought that they—even though they're writing these complicated equations, "This is the scale of potential of the Higgs field," they put this little part in the paper where it says, "We should perhaps finish with an apology and a caution. We apologize to experimentalists for having no idea what is the mass of the Higgs boson, unlike the case with the [tarm 82:54] if we're not being sure of its couplings to other particles. For these reasons, we do not want to encourage big, experimental searches for the Higgs boson. But we do feel that people performing them should be..." figure out how it should turn up. That's funny to me because that was one of the main reasons why the LHC was even built in the first place.
But it was thought of as sort of an afterthought, until it became more and more necessary to explain some other things. That's the part that I wanted to get to here because the reason—and just as a side note, one of the things that we have done at the LHC at 13 TeV is we rediscovered the Higgs boson, hooray. It's nice to see old friends show up again, even though old in this case is only from 2012. But the Higgs boson did show up again in our data, both here and this little red blob definitely, so the Higgs does exist. We're studying its properties and actually, I didn't get a chance to talk about my specific research a lot. I worked on the di-photon excess that was in the news a lot, but I also do a lot of things with respect to the Higgs boson.
But one of the reasons why the Higgs boson, after it was predicted and after people were like, "Well, let's not do experimental searches for it. Let's just see if it shows up somewhere," people started to think about, "Hold on. What possible consequences could this have?" because they looked at it a little bit closer and they noticed that there's actually a big disaster with some of the W and we call it the electroweak force. These W and Z particles, any time you see a W and Z particle, it refers to this thing called electroweak force.
There was a gigantic disaster for some of these scattering amplitudes. Like I said before, you can draw these diagrams and as long as it's not forbidden by the symmetries of quantum field theory, it's fine. You can draw it and it totally exists and you can calculate the probability that if you were to design an experiment, you would be able to see this effect.
The problem is that they started to do these—they started to calculate these diagrams for these W bosons. It's called W scattering. The probabilities were greater than one. I hope there's some mathematicians in the room, or even just regular citizens, to look at that and say, "That's crazy. That doesn't make any sense at all. You can't have probabilities greater than one." As the center of mass, energy grows. You get these probabilities that go really, really high and this was something that was called a catastrophe.
They found out that if you just put in this Higgs boson, it totally is called regulating these infinities. So, it turns out that we actually—the existence of a Standard Model Higgs boson yields meaningful predictions for these vector boson scattering things. But it doesn't have to be the only one. They thought about, "Okay. The Higgs boson." There's no reason for nature to only have one Higgs boson. In the diagram, it's nice because it's right in the middle. It suggests there should only be one and we found it, great.
But there's no reason why that should be the case. There could be families of Higgs bosons out there. That's one of the things that we're also looking for at the LHC. This could be the Higgs, but the one that we found, is it actually the small "h" or is it like a big "H"? Maybe there's a smaller Higgs boson with a smaller mass that we missed because it's hard to find. Maybe there's a whole family of other particles that we're looking for.
In fact, I think I'm going to skip this for time, but the Higgs boson itself, once you know its mass, once you know this black line—this is where the Higgs boson actually exists at 125 GeV, you basically know all of the percentage of the time that it will split into Standard Model particles. You know that. This is what was calculated with the Higgs prediction. Like I said, they didn't know what the mass was, so if you've seen the movie, Particle Fever, that's all about what this is. It's like we had to go out and just kind of scan the mass range and see if we find something. We're cartographers. We're mapping out territory and there was.
We found it at 125, but once you knew that, you know all these other—the places where those lines intersect that black dotted line, that gives you a percentage of the time that when you create a Higgs in the LHC, it lives for like 10 to the minus 23 seconds. It will then split into other particles, the ones that are in those percentages right on those lines.
So, more or less, we have to measure the Higgs boson decaying into those channels and then, see how close they are to the prediction. More or less, they're pretty close on the right here, on the right plot. They are pretty close to what we'd expect the Higgs boson decay to behave except we're never—you see those arrow bars on those and they're not exactly on the prediction of the one here. Some of these are off to the side.
We will never be able to get really, really good precision at the LHC, even over 20 years' worth of taking data. We'll never be able to pin this down exactly with respect to the Higgs boson, so one of the biggest things that we're testing at the LHC is testing that the Higgs boson could actually be the thing that is the portal into new physics, portal into new particles that we've never seen before because the Higgs, for a lot of other reasons, it's a weird particle.
It's the only scaler field—it's a manifestation of the only scaler field we know and it also has something called a very small width, which means it's really susceptible to somebody bugging it, like a new particle could totally bug the Higgs and it could take up some of its branching ratio. On the X axis—two minutes, I'm sure, one minute, guaranteed—the branching ratio here for the Higgs going to new particles could be something as much as 30%. We don't know that, so this is something that we're—actually a lot of my research is finding ways that there could be some new thing in here that takes up part of the Higgs bosonbranching ratio.
I don't think I'll get a chance to talk about dark matter, sorry. Questions? Technically we have 10 minutes for questions, which I completely bowled over. But quantum black holes, supersymmetry, dark photons, we're looking for all these things. We've got 20 years to go, so stick with us because there's a lot of stuff that we could be discovering. You have to be patient.
But at the end-of-the-day, what if we find nothing? That actually will be more interesting, to be honest, because that demonstrated to us there should have been new physics around the corner at LHC. But if you don't find something new, that still gives you a very valuable piece of information about nature. You now know. Like I said, we're cartographers. We're mapping out territory.
We knew that—remember that slide that I showed with the old LEP tunnel, 209 GeV. We knew that there—we suspected that there was new physics at the TeV scale. We only got to 13 TeV. The TeV scale could be something, the hundreds of TeV. This is the next project they're talking about right now would be even like an 80- or 100-kilometer long tunnel that would either be here or maybe in China, something like that, that we get up to like 10 times the energy of the LHC.
This is the conclusion. We have just entered a new era of particle physics at the LHC. This is completely unknown territory, uncharted territory. Once again, whatever we find is going to be revolutionary because even if we don't find something, that tells us that 13 TeV was not the level, was not the limit that we needed to go to. We need to go higher energies and we need to be clever about what we look for because the nightmare scenario at—well, that's not—the nightmare scenario at the LHC is not that we get to the end of 20 years and we don't find anything.
The nightmare scenario at the LHC is that we get, after 20 years, then, Jill Theorist raises her hand and says, "Aha. By the way, the reason you didn't find new particles at the LHC is because you didn't keep the right events." Remember I said we toss out like 99% of our data. Someone should ask me about it, but we have really good reason to believe that we're tossing out just boring data, but what if we're wrong? We don't know this. In 20 years, Jill Theorist could come up with a reason why, but that's why right now, we have 20 years' worth of running to do. We're spending our time to really go through to make sure to make this as remote as possible.
The old paradigm particle physics is dead. Our first look at 13 TeV killed it because there's no more guarantees. I just want to leave you with this. Particle physicists are explorers and we're necessarily collaborators. The open questions are actually too big to be answered experimentally by one person. They're simply too complex to be addressed by one people group. Diversity makes us smarter and multiculturalism at CERN makes me a better physicist.
As a result of this scaling up and the difficulty of answering the open questions, the Nobel prize is actually obsolete for high energy particle physics because there's not one person that's doing these discoveries. There was a Nobel prize for the theoretical side of the Higgs, but not for the discovery. It's basically an obsolete metric with how to measure brilliance in particle physics.
But even though the experiments and the collaborations are getting larger, the fundamental concepts are the same as when my friend and I were staring at the stars a mile away. You have some idea and there's something you want to know, somewhere you want to explore. You go out and test it because belief has nothing to do with it. The data are immune to your feelings and your desires. The data don't care about your company's investments, for example. Facts are real. Empiricism is the best method that our species possesses to determine truth from falsehood and science, free from politics and prejudice can benefit all humankind. Science belongs to everyone.
If you've ever been curious about anything, wanted to know about how something works, to come up with an explanation that withstands scrutiny, then you are an explorer. You are a scientist and you are an honorary particle physicist. There is no failure in particle physics when you're an explorer. The absence of the discovery teaches us something about nature. The only failure is to stop searching. Thanks.
Moderator:
Amazing. Thank you so much, Doctor. We knew it was going to be a smashing presentation, right, everyone? I'm sure there's got to be some questions from the audience. Let's go right here.
Question:
What are your thoughts on the Superconducting Super Collider that was cancelled about 10 years ago because I heard it was going to be bigger and faster, or stronger, than the LHC. Do you think if that was continued, we would have found the Higgs boson and other particles faster?
Beacham:
Absolutely, yes. We would have. For those of you who don't know this, Superconducting Super Collider was a planned particle physics accelerator in Texas. It was going to be twice as much energy as the LHC. It was going to be a really fantastic machine. It was shut down by Congress in 1995. It would have been discovered. The Higgs boson would absolutely have been discovered there. We would have been to a higher energy level that we had a range to find new particles that we'll never be able to find at the LHC.
Like all particle physicists, I wish that the SSC would have been built because it was much higher energy. However, the other part of me is kind of glad that it was not built, to be honest, because if the Higgs boson had been discovered only in Texas, it would have been possible to claim that it was only an American thing. It was like, "Oh, yeah, America did this." I have no problem with that, except that the Higgs boson sends an amazing message to the world. This really was a world discovery. This is the best that humanity can do coming together. I'm of two minds about it. I think a lot of physicists are.
Question:
You showed the graviton and other, like possibly exotic Higgs bosons on your more expanded Standard Model. Those would go in the middle with the other bosons, not on the outside, right?
Beacham:
The extra Higgs bosons or the gravitons?
Question:
The extra Higgs bosons and the gravitons.
Beacham:
Yeah. The graviton would have to—you'd have to find a space for it somewhere in the middle because it would be a force-carrying particle. It's a little bit complicated with this version of the graviton, but yes.
Question:
Thanks for the presentation. I was curious about the switch from the 8 to the 13 TeV. We're a little disappointed. We didn't quite get to it, but how exponentially—I mean, is it possible that you might get something at 16 TeV? And at what point do you decide to break down and create a new energy? Do you go up to the next level and like, "Okay, we have to double this." Is it exponential to get to the energy to find really new stuff?
Beacham:
It's not so much exponential, but it's directly related to the radius of the ring. The reason why 13 TeV, why it's 13 and not 16 or something like that, it actually was supposed to be 14 because that's the highest we can get with this 27-kilometer tunnel with the magnets that we have, with protons.
Question:
So the answer is maybe get a new ring?
Beacham:
Yes. That's why this little schematic here was so suggestive. It's like the LHC is the small ring. This would be an 80 ring that they want to dig under Lake Geneva. That's awesome.
Question:
Could you tell us briefly what—you started to allude to some kind of relationship between the Higgs, or perhaps the Higgs family, and dark matter. Could you elaborate on that a little bit?
Beacham:
The relationship between the Higgs and dark matter. I had mentioned dark matter. Dark matter is a whole, hour-long discussion in and of itself, but dark matter, we know it exists because we see its effects on the cosmos due to gravity. We know it exists from other observations. There's empirical proof of it. We know that there's more, as Mordecai said, if you go out and measure how fast a spiral galaxy is moving, how fast it's spinning and you just count up all the matter you can see that's luminous matter, it's actually moving way faster than it should with just luminous matter.
That's why there's got to be more M there. It's just equations of gravity. You can put the amount of matter you see in there that tells you how fast the star should be going as it's going around the middle. We know there has to be more matter there pushing this, but if we can't see it, if it's not luminous, then it's dark and it's dark matter.
But the problem is we don't know what type of particle dark matter is. We know it exists, but we never actually have seen it in the lab. Once again, since we're in the crazy, smash together little kid particle business, we want to smash it together and try to create it in our laboratory setting. There's a lot of different ways that we could see it.
The connection between the Higgs boson and dark matter is not so direct, except for the fact that the dark matter particle, if it is a particle, it has to have a mass that's pretty high because otherwise, we would have seen it before and because the Higgs is the way it is, we still have this huge possibility of new particles that the Higgs could decay into that we can't—that we have to probe directly.
Like I said, the LHC, one of the other reasons why we have to build this bigger detector, bigger collider, is because the entire run of the LHC, we'll never be able to pinpoint down the Standard Modelness of the Higgs to precision. It's always going to give you some wiggle room, so that means that to prove to ourselves that the Higgs boson is very much Standard Model only, there's only one H in the middle of that diagram and not just some family of other stuff, we have to go to higher energies. We're not going to be able to do it with precision and one of the possibilities is that the Higgs could decay into a dark matter particle. This does exist and it's something we look for. We have papers and searches for this.
Question:
About a year ago, the graviton was observed at LIGO. Is there any exchange between CERN and LIGO?
Beacham:
Yes. In fact, what was discovered with LIGO was an amazing discovery. This was gravitational waves. This is a prediction of general relativity and what that did, it's a fantastic discovery. It opens up a completely new realm of observational astronomy, a different version of observational astronomy we've never had at our disposal before. But what it does is it actually puts a limit on the mass of these Standard Model-style graviton.
That's why I was alluding to the question over here. When we're saying this two-photon style graviton with the extra dimensions that it lives into, this is not so much the plain vanilla graviton. This is a little bit more complicated thing called a Kaluza-Klein or a Randall-Sundrum graviton. The LIGO experiment, they discovered this thing called gravitational waves. You look in their paper. You can just do the calculation with standard quantum mechanics stuff. This puts an immediate limit on the mass of the graviton, the standard graviton, just because we see what the wave length of this gravitational wave is. It has to put a limit on this value, we think has to be something very close to zero.
However, it does not mean that we have discovered, in terms of a particle, the graviton itself. It's related to it in that sense, but it's different because this graviton that we're talking about here is a little bit more complicated. When you put new extra dimensions in there, it complicates things quite a bit.
Question:
Is each highest TeV like an umbrella on all of the lower TeVs, or is it possible that there could be particles found at TeV 9, 10, 11, 12, that can't be found at 13?
Beacham:
No. It is a good question and more or less, the umbrella thing is true, yes. If we go 13, that guarantees we can find the other things below that. Depending on what type of particle you use to collide, like the large electron positron collider was in that tunnel beforehand, electrons and positron collisions are way cleaner, so you have the possibility of being able to sift out small effects more efficiently over your background because what we're doing with all these little bumps, the bumplet things, you're looking for a tiny effect over a huge swamp of background.
With proton collisions, protons are actually really messy beasts and so, the collisions, they give you all this crap and like I said, these 25 collisions per bunch crossing. Electrons and positrons, way cleaner, way easier to sift out small effects under the background. You can definitely find things that are at the lower energies. If you designed a very specific experiment at a lower energy to look for one thing that's very clean with respect to backgrounds, then you could have a better chance to see it first there than you would at your other thing.
Question:
Thank you very much. Really interesting talk. I was wondering why do the theorists get all the glory and what if you find a particle that has completely unexpected properties? How do they divide up the Nobel prize?
Beacham:
I think that your question, as an informed member of the populace and a citizen, should be directed to the Nobel committee and not me, instead, because this is a question that we have talked about for a long time. I'm not the first one to say that the Nobel prize for particle physics is obsolete for [expandable 102:25] physics. People have been saying this for a long time because the collaboration size is huge.
No one person discovered the Higgs boson. If someone ever tells you that they discovered the Higgs boson, they want one of two things, a job or a date. It was discovered by like 6,000 people, plus a few thousand other people. If there's some new thing that's discovered, the processes that the Nobel committee goes through are mysterious to me. I'm not exactly sure because also, it's contentious the whole time. Why did they pick those two guys for the Higgs discovery when there were several different names down on that mechanism, several of which are still alive? Why did they pick the two? It's a little bit mysterious and so, that's why I very much appreciate still that the Nobel prize is a really nice, kind of hangar for attention and it get people excited about things and it's a nice benchmark for a lot of things.
But on the theoretical side, for instance, X(750), that's a good example. Five hundred papers were written about this. Which of those guys is going to get the Nobel prize if it had turned into a discovery? I have no idea. There'll probably be some arguing about who came up with it first and somebody from back in the 60s would say that there was a Russian guy came up with it first. That's typically what happens. But the Cold War was bad for science. This is another reason why multiculturalism and open information exchange is good.
I don't really have the best answer to that. If we find something new, then those of us in the experiments will redouble our efforts to explain to the public why the research that we do is so important and why it was only possible to do with the wisdom of multitudes of people around the earth.
Question:
If you get another particle, are you going to be more discreet about it until [inaudible 104:12] in time?
Beacham:
No. There's no—we announce two sigma excesses all the time. It's not like—but the thing is, the news jumped off of that. The theorists jumped off of that. People were like really—because everyone was really excited and we were excited, too, but as an experimentalist, every experimentalist is secretly a theorist. Let's put it that way. But as an experimentalist, you have to be a dual person. You have to be the excited little kid who's like, "Oh, my god. What are we going to find? What if this is something new? Ooo, awesome. What are the interpretations going to be? Is this going to be a graviton?"
But at the same time, you have to say, "Hold on. I'm an empiricist. I have to wait to see if it crosses my threshold for evidence, for demonstration." You have to be both of these things simultaneously. It is difficult sometimes, but that's what science demands.
Question:
What's the status of the funding for that larger accelerator? What particles are you expecting to find? Has anybody ever thought about a particle above 13 that they suspect they can find with this larger accelerator?
Beacham:
Tons, yeah. Basically, all the stuff that we have not found at 13 TeV. Oh, this is going to take a long time for the animation. The status of the funding is still unclear. Basically, a lot of people have committed—a lot of countries—have committed to scoping studies for this. They're not really at the point yet where they have solidified budgets. They have proposals and things like that, but it's not exactly certain where the best place for the next one to show up would be.
It might be the best place to be an CERN. I think that it definitely should be at CERN. It should be like an 80- or 100-kilometer tunnel at CERN. It's also possible that China has enough resources and money to just do it themselves. They are actively pursuing this, as well. The type of particle that could go inside there is also a constant argument amongst us.
Some people say that, like this question here, we should use electron and positron because it's so much cleaner because instead of two bags full, ugly proton bags full of quarks and gluons that smash and do a bunch of crap, you have point particles that go, bling, bling, bling. You have a full, [for-momentum 106:28] vector you can do fantastic things with. You suffer from some other things because this, along with some things that we have not discovered at the LHC and things that we could possibly discover at a higher energy collider. If we were trying to find some of these effects that would be extremely subtle, it might be easier to find at an E-plus, E-minus machine, we call it.
However, other people say, "No, we should do a Hadronic machine because we already have an LHC." The H is for hadron. "We already have a proton machine right now and we have tons of experience with it. We have tons of knowledge. We should take advantage of this knowledge that is alive right now. We could pass it down and build a big hadronic machine." This is kind of the status. It's still TBD.
Moderator:
We'll be looking forward to having you back in the future and give us an update. Thank you so much.
Narrator:
Thanks for listening to Public Programs at the American Museum of Natural History. To listen to our archive of podcasts, visit amnh.org/podcasts.
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Support for Hayden Planetarium Programs is provided by the Horace W. Goldsmith Endowment Fund.