 Well I'm extremely sorry that I couldn't be there in in a person this time because of some I'm difficult these on on on the sense on the Most of my my friends and help to there know these the RCTP is one of my favorite places and this school is one of my favorite places to Electra So but I'm very happy that at least we managed to Get one thing Presented in this way, we'll see how it works now. I know that this is a this is a school on more formal topics in In theoretical physics my original intention Given that the LHC is starting back up imminently was to give a series of lectures on On on hadron collider physics just the most basic aspects of hadron collider physics so if you're a Think there is to a formal quantum field theorist or a cosmologist Someone who doesn't spend their their their lives thinking about Hadron collider physics you'd have some idea of The basics of what's going on this is a general subject How to think about collider physics that was part of a bread-and-butter education of a particle Maybe 30 years ago But you don't find to present it so much in textbooks anymore and it's really perfect for a school So that's that's what I was finding on doing but given that I couldn't be there in person and I I hate giving computer top period and the whole purpose of The point of the lecture that I had in mind was to sort of slowly present this Slowly present the subject from the ground up. I'm not going to be able to do that But I will do something else instead in this one lecture. I will still give you a more quickly a broad overview of Have a think about collisions at the LHC and also what to expect for this year and for the next few years Since this is very likely going to be the most important Period the next couple of years are likely going to be the most important in exact period in the running of the LHC At least far as probing for physics beyond the standard models Which is something which is more reasonable to be done computer talk like this especially given everyone Almost all of you except for the perhaps some of the lecturers are young in your 20s or maybe early 30s I'd like to tell you about Something that many of us are very excited about An accelerant pump so the next step beyond the LHC the motivations for doing that And how to try and make it happen And I think particularly relevant For an audience of your age because if such a facility is built It'll be the machine for your generation. Certainly not for mine. I'll be wondering around for the cane maybe But but it's easy a machine for your regeneration. So I think those are the two things I'd like to talk about A more detailed set of planning on talking about which is a more detailed Introduction to hydroencellator physics But can't be there in person. Maybe I can I can suggest the following pictures I gave at the At the summer school that we have at the IAS all the way back in 2008 although the basic subject matter chains obviously You can find online at the Institute website And it was called LHC crash course at the PIPP 2008 but The the first is going to be More quickly and with a little bit more a little less detail talking about What I covered in three three or four course in those like Okay, so let's get started with the LHC And here's some the LHC most of these things you guys know The LHC is a proton uncle and the center of mass energy the collision TV What the a TV and now when it's starting back up the initial design energy was It's not obvious. We're gonna get up 14 feet. We might cut up 13 and a half TV. Maybe 14 feet I'm sure you all know another extremely important Number is the luminosity of the machine and the instant luminosity It 10 to the 34 per centimeter squared per second and we're going to see in a second Why did it have to be 10 to the 34? Why didn't have to be 10 to the 44 or 10 to the 26? What's special about the number 10 of the 34? We'll see that Luminosity is the number of events a process if that process has a cross-section Sigma the number of events is sigma times those There are some units that we tend to use for cross-sections in Particle physics of course since we're part of this is we really should do everything in natural units Let me just remind you what natural units are if you're a if you're a if you're a Someone who doesn't know these unit conversions by heart Go up into your closet and learn them Because they really need to be on the tip of your your time Okay, so the standard unit conversion is that the proton has a mass of around one g e v In fact, it's so lucky that it's math is close to a g e v I think we should redefine G to be the mass of the proton But anyway, the math of the proton is around one g e v the size of the proton is around one over a g e v and That size is also around 10 to the minus 14 centimeters That's the most basic Unit of conversion that an inverse g e v is around 10 to the minus 14 centimeters And inverse TTV which we're cropping up the LHC is about 10 to the minus 15 centimeters And so you start seeing why that number 10 to the 34 percent of meters square per second where that came from because That 10 to the 34 is allowing Roughly speaking TTV seal process to happen on a human time scale of second We'll see a little bit later that it's a little slower than that But that's that's roughly what you want now units that we introduce and talking about things in part of physics It's a unit area or section called a barn I think a joke amongst the some experimentalist 40 or 50 years ago. I had no idea why they decided to A barn there are many stories for what they did, but anyway a barn is defined to be around 10 to the minus 24 centimeters If you send two protons together Smashing into each other the Sorry Nima we cannot hear you now Okay No, it's okay. No, it's okay Processed strong interactions is the hadron collider section will go like alpha s squared Divided by the energy so divided by around a TV square alpha s is around point one And so alpha s squared over TV squared is 10 minus 36 centimeters square So that's around a pickle bar the LHC so in the next line He's starting from around a millibar that was to remember the size of the proton 10 to the minus 27 centimeters square And then I don't remember what SI units are so I there's millipedes and micro then nano then pico Then pencil, but a pico barn is around 10 to the minus 36 centimeters where Are the typical LHC cross-section what the 10 to the 34 percent of meter squared luminosity is Instantaneous luminosity is fine for you. There's the there's a billy event the sex now Let's talk about some other processes in the standard ball for example the production is around a thousand people aren't so that's around 10 events every second now think about what a huge leap that is because the top fork after all was discovered at Ferry lab in the mid 1990s that's around two TV center of mass energy And when the top fork was first discovered they discovered with a handful of events 14 15 events Okay, so that was a big triumph of the mid 1990s now We're going to produce 10 of them sex work in an empty downcourt coming together single dumping production or single z production is around TV scale that's just we talked about the typical process section of about a pickle barn You have to beat down in order to be able to pick those very rare events out compared to the Sorry, Neema again. We're not hearing you Is this better now? Yeah So why is it that we have a prayer of picking out these ordinary processes? These rare process over the ordinary one The most basic thing is that is that Completely breaking apart into other Strongly interacting had run that go probably back-to-back and to direct to the team came from the pinnacle Interested in the events where the where the point like Side the proton head large angle relative to the beat So that's one of the basic It's also true for the for the production of the top course and the W's is for beating down background This is a big job. Sorry Neema again. There is a problem. It seems I'll maybe speak a little more slowly For instance, if you produce the part that way you be Neema I think there's we are going to call you back just hold on for a minute So One more bit of terminology you often hear people talk about the integrated luminosity Which is a measure of the total amount of data, which is going to be a gather in a particular period of time So the integrated luminosity of run two of the LHC, which is the one that's just about to start now Is going to be around a hundred inverse femtobar now. This is a this is a good unit Because because it allows you to immediately figure out how many events of a given cross-section You can expect to get in that run. So if we have if we have a cross-section of a picobar then With a hundred inverse femtobar We will get well picobar as a thousand femtobar and if we have a hundred inverse femtobar Then we get a hundred times a thousand or ten to the five events So that that that gives you a measure and you can also see what we're what we're Going to have in the coming years with the LHC. So by the end of run two Which is going to be I think sometime in 2017. We'll have correct collected around a hundred inverse femtobar of data By the end of this year, we should maybe have around 20 inverse femtobar of data By the end of run three, which is going to be sometime in 2020 We'll have 300 inverse femtobar of data and people are talking about a high luminosity upgrade of the LHC which would get a factor of 10 more data than that 3000 inverse femtobar. So let's move on now if you go to any talk on the LHC let's say you're talking about the The search for supersymmetry at the LHC You'll see a plot that looks like this and this is this is a cartoon, but this is a typical cross-sections for supersymmetric particles and and you see that on the Vertical axis is the cross-section in femtobarms starting up at around a thousand people barn To a pico barn to around a femtobar. Colored supersymmetric particles have cross-sections that look like I've shown So they range from maybe a thousand people barn if they're light is a hundred GB. Of course, they can't be that light anymore Very likely given what we've learned from the LHC, but this is the sort of box that you would have seen before the LHC turned on They go all the way from a thousand people barn down to about a femtobar Or less if you go up to around the TV scale and the production cross-section for uncolored particles So things that only have electroweak quantum numbers are around a thousand times smaller, but they have the same qualitative shape Okay, they all They they they go down like that now if you look at a plot like this You might be positive Because well first of all it indicates the great challenge to experimentals because it looks like they have to be prepared for And they continue to have to be prepared for cross-sections that could vary by almost a factor of a million between just a hundred GB and a TV okay, and of course also Ultimately between the colored guys and the uncolored guys cross-actions that can vary by as much of a factor of a billion going from one to the other But if you look at a plot like this You might wonder why there was such a humongous difference between Producing particles that weigh a hundred GV and a TV After all if you think about your elementary quantum field theory courses, you know that All the couplings that we talk about either in the standard model or you know in supersymmetry or whatever All the coupling constants are dimensionless. They're reasonably large, you know, so alpha s for color is around point one And Everything else you think is given just like dimensional analysis So the cross-section as we just estimated before the cross-section goes like alpha s squared Over the energy squared over the center of mass energy squared So you might have expected to see a variation by about a factor of a hundred in these plots But instead we see a variation by factor of about a million in these plots. So what is the difference? What is the difference? Why are we getting a factor of a million and not just a factor of a hundred? If I go to the next slide so here you don't have to look at these things in any detail But just so you see that it's more than a cartoon The next slide shows so characteristic cross-sections for the LHC at 70 EV Okay, so this is that the run that was just Completed seven. I think this was seven and not eight, but anyway, and just so you see it looks exactly like what I was showing you before Okay, and you see this huge variation of a factor of a million in the production of gluino pairs at the top Squark pairs at the top all the way down to Sluptons at the bottom If you look at the scale on the graphs, of course you see that the the big difference between colored particles and uncolored particles But you also see this characteristic very fast drop As a function of For the cross-sections as a function of the mass. So that was a picture at at 7 TV Here's a picture of 14 TV Anyway, you see exactly exactly the same thing So all right, so so that's one thing that you could be That's one qualitative thing to be tend to say Now something else that you might naively wonder is this Everyone seems to be very excited about the next run of the LHC turning on but why are they so excited? I mean after all we just had a run at 8 TV and now we're going up to 13 TV 13 doesn't seem that much bigger than 8. So why is it going to be such a big deal going up? From from 8 to 13 if you think along those lines you might You might actually extract a little bit more Why were people so excited and going from the Tevatron to the LHC of the Tevatron at a center mass energy at 2 TV? The first run of the LHC was at 7 TV. So that's just a factor of three and a half Why the hell were people so excited just about a stupid factor of three and a half? These two questions why the cross-section in the previous plots are varied by a factor of a million and Why these modest seeming gains in energy are people are so excited about they both have a common answer and We can see it in in this slide. The reason is that there is a crucial qualitative fact about collisions and hadron colliders Which of course you all know you all know about the famous part on model. You know that It's not true that we should think of the proton is just being made out of an upcork and and two downcorks Or sorry two upcorks and a downcork even worse those two that they have these constituents that are Three constituents that are banging into each other In we should instead think of them as a big messy bag of Those valence quarks the two upcorks and the downcork But they radiate they radiate the gluons and the gluons can further split into quarks and anti quarks and these splitting processes Can continue more and more and more and so so so in fact depending on the Depending on the the energy scale with which we're taking a snapshot of this collision We can either see the proton is being made out of a few partons or more and more and more partons and if the and in fact it's more and more likely to see the Energy of the proton shared with more and more partons as you go down to lower and lower energies Center of mass energies for the collisions of the apart and that means that if I think of the cross section if I think of the cross section For some processes that's initiated by two partons a and b banging into each other There's the naive Scaling that we talked about before something that just goes like one over the center of mass energy squared one over s So some dimensionless amplitude over s that that's the usual naive factor But then there is a very important factor that tells you how likely it is to find partons carrying those carrying the energies for those collisions that factor ultimately comes from the part on distribution functions and Here it's subsumed in in something that's called the part on luminosity. Okay, so that that that gives you a measure as I said of how likely it is to find The part on the side of the proton carrying that fraction of the energy The the details of how to think about this in the part on model and so on that's one of the things that is discussed in those old Lectures that I mentioned But for now, you'll just have to take it for on faith that We can measure these part on luminosities Experimentally we can measure them for example Ultimately, we can measure the part on distribution functions from other experiments like deep and elastic scattering and Other places and then use them for have drawn hand drawn collisions And the very important point is that these part on luminosities are very rapidly falling functions of s the very rapidly falling functions of energy So you can see that on this slide Also on the on the What what what's plotted is the is a part on luminosities for different pairs of initial states for the proton for the part on so so there is for instance quark quark Or quark anti-quark the quark quark is in blue quark anti-quark in red Quark glue on in green and glue glue in In the yellow so this shows you how much this sort of naive picture But the proton is made out of two up quarks and a down for okay In that naive picture of the protons made up to up to and a down for it You would think that the only The only part on luminosity would be of two quarks banging into each other And so you see that that's that's sort of roughly true this quark quark part on distribution function Which is a guy in blue is the biggest one when you go to ultimately sufficiently high center of mass energies for the collision up to you know And a bigger than around two and a half TV or so The a quark quark luminosity is the biggest but already as you go to lower energies and And those lower energies are the ones really relevant for the for the production of most of the things that we're talking about The quark blue on becomes the biggest one Okay So so and if you go to even somewhat lower energy still you don't quite see it on this plot But some somewhere around 500 GV a Little lower it's actually blue on blue ones which have the biggest the luminosity. Okay, so So you should really think of the LHC is the blue on blue on or a blue on quark collider More than as a quark quark collider Okay, of course, there are some qualitative things that that are roughly correct. You see that the quark anti-quark Part on luminosity is maybe about a factor of 10 smaller than the other ones And so that does reflect that it's a proton-proton machine and not a proton anti-proton machine But still they're not all that different from each other and that's the So a this is just crucially reflecting this basic and deep fact that we should That what the proton looks like is dependent on the the energy with which We probe it and be you see how rapidly falling these things are notice that the vertical scale is logarithmic, okay? Now because of that So if we go back this factor row AB as a function of s is very rapidly falling And so this has this has a very important consequence Two very important consequences one is that any particle at the LHC any massive particle is produced roughly near-threshold Okay, now again This is this is completely not what you'd expect if we're colliding electrons and positrons if we're colliding electron and positrons at One TV and we are producing top quarks Which way in 175 GB then the top works would be coming out with humongous energy Okay, they're becoming out very boosted This is not true at the LHC Every or at any hadron collider Massive particles are typically produced at threshold and they're produced at threshold because That this falling part on luminosity is such a heavy price to pay that that that that the production is dominated by Taking place at the lowest possible energy that it can Okay, so Now secondly By staring at these part on Distributions as a rough rule of thumb and so so as you see it The part on luminosity is depend, you know, they have some detailed shape. That's different for the different Underlying part tons. So this formula is a rough figure of thumb But if you naively thought that the cross-section goes like one over mass squared Then the correction from the following part on luminosities goes roughly like the center of mass energy Divided by the mass of the particle to the fourth the center of mass energy of the collision You're talking about divided by the mass of the particle to the fourth Okay That that for you know, it's it's a number it can go from like 3.3 to 4 or something So that's again just a rough rule of thumb But you see that the cross-section goes like then roughly the center of mass energy to the force Fourth over the mass to the sixth This formula explains all the qualitative things we saw in our previous plot First it explains why it is that the cross-section is very by factor of a million because when we vary the mass by factor of 10 Again, there's just extra one over m to the fourth compared to what we expected before and it's actually tells you why people are so excited even with factors of only two increase in the Center of mass energy of the machine because at a fixed mass the rate for producing the new particles scales like a pretty high power of The center of mass energy scales like about the center of mass energy to the fourth So not only is it true when you go to higher energies that of course you have access for producing heavier particles That's obvious But also the rate for producing particles in a fixed mass scales like this high power of the center of mass energy The machine and so we can get a more quantitative estimate for how much more exciting one two of the LHC is relative to run one So run two first it's going to have a hundred inverse femtobar of data versus around 20 inverse femtobar And that was gathered in run one So there's just a factor of five in the amount of overall data But also we win by this a factor of the ratio of the energies 13 TV the 8 TV roughly to the fourth power and actually we win a little bit more than that So by the time that you have put it all in run to what's going to be completed in the next couple of years is going to be Roughly speaking a hundred times more powerful than run one. It's going to gather, you know, roughly a hundred times more of the same data Then then we could have gotten in run one in addition to having access to slightly slightly Somewhat heavier particles. Okay, so just to accalibrate that again in the first month of running in the first month of running in run two Only one inverse femtobar gathered or so The effective data set that we'll have will double relative to what we had from run one. Okay, so so There's two broad lessons then that you can take away from From what I told you about the LHC So these if you remember nothing else from this this this part of the lecture, this is this is what you should remember So first the LHC is fantastic at producing colored particles. It's obvious. It's colliding protons And the reach for colored particles goes from about one to three TV Um, the reach for uncolored particles just electric particles is about a factor of, you know Five six Smaller than that and goes from maybe two hundred to four or five hundred G. Okay So the LHC is really powerful at producing colored particles And the reach for electric particles is roughly in order of magnitude smaller So that's one thing and secondly you should remember this rough scaling of the cross-section going like center of mass Energy to the fourth overmaster the sixth This is a general fact of life at Hadron colliders And it tells you that by far the biggest gain that you get is with increasing energy Versus gathering more data at a fixed energy Okay So and that's why every time there is an energy upgrade the biggest excitement the biggest bang for the buck Comes right away. Okay Because you you win by that fourth power after that you're just accumulating more and more data so you're sort of your game is linear in in the amount of in the amount of Data that you gather, but you get this fourth power When whenever you make these jumps in energy and this is why this period from 2015 to 2017 In run two we'll be by far the most exciting period of the LHC running Because we get this energy gain relative to run one all right, so Now I apologize. It was a slightly busy slide, but I just wanted to illustrate Some of these points just so you have an idea for what we might know when okay, so let's say we're interested in Producing super partners at the LHC so we're interested in the gluino. Okay Right now there's a limit from the LHC depending on precisely how the gluino decays and so on same in It in over a broad range of parameters space the gluino has been excluded at around the two sigma level up to around 1.5 The gluino could be at 1.4 or 1.5 TV and we would not have known it so far from run two If the gluino decays in a slightly more exotic way or things are a little bit slightly different Maybe it's been only excluded down to a TV. So the the the red curves we're going to be talking about correspond to the case where the gluino is But let's only focus on the record. Okay, so I don't want to Yeah, let's just focus on the On the record. All right, so so so let's say that the gluino is really sitting there at 1.5 TV It's been excluded at two sigma. Let's say at 1.5 TV by run one What this is now showing you what the red line is is what the two sigma exclusion will be at 13 TV at the LHC as a function of the Integrated total integrated luminosity in inverse from the bar. Okay, so you see that right away Right away. I mean we can't even see it Right Right where the red curve starts So basically with an inverse from the barn or even a little less of data run two will already Repeat what we learned at run one and we'll and we'll exclude a 1.5 The 1.4 TV gluino now, let's say that we continue not to see the gluino Okay, let's say that that that's still nothing has seen by the end of this year. So the end of this year We see that so here is the 2015 the end of this year around 20 inverse from the barn of data if we don't see anything We'll put we'll be able to exclude the gluino up to around 2 TV Okay Now let's say that we continue not to see it I'll come back to the optimistic scenario in a second But let's say that we go all the way to the end of run two with a hundred and with a hundred inverse from the barn What will what will we have done by then well, we'll exclude going up here around the 2.4 TV gluino Okay, now let's say that we still see nothing up to 2020 In the end of run three then we're up here. We exclude a 2.5 TV gluino and Asymptotically we'll get maybe you know a few thousand inverse from the barn With the high luminosity LHC run. So this is infinite time on this axis Okay, but you see that even though, you know, even going all the way up will get not up to maybe a 3 TV gluino right Excluding a 3 TV gluino. So So again that that that that shows you what how powerful The gain in energy is relative to just accumulating more data As I said if the galinos If the galinos right around at one and a half TV, we'll repeat that exclusion in the first month of running But over the entire future period of the LHC We'll cover the range from one and a half TV to three TV for the a gluino now the Congress of Everything I was saying and all of these plots all of these things are just reflecting that basic physics that I was Telling you about before The centered mass energy to the fourth one of a mass of the six on all of that stuff now Let's say conversely. Let's say the gluino really was at 1.4 TV We just barely missed it at the first one of the LHC. Okay, so a two sigma exclusion This is another rough figure of merit a rough rule of thumb that That the number of events that you need to exclude something at five sigma Sorry to discover something at five sigma is roughly ten times bigger Than what you need to exclude it at two sigma to not see it at two sigma. So so that means that that that If the galinos really at one and a half TV then it wasn't seen at run one and it was excluded at two sigma Let's say 1.4 TV was excluded at two sigma in run one, but the something that was excluded Or right at the limit from one one could be discovered at five sigma by the end of this year Okay, so that that that again shows you the power of the leap in in energy and so on the On the vertical axis here in purple. I've indicated what the discoveries could be so so So Sorry in in in blue. I've indicated what the discoveries could be so so one and a half TV We know could be discovered at five sigma by the end of this year It could be discovered up to around 1.8 1.7 1.8 TV by 2017 could be discovered up to 2.1 TV by 2020 and And of course we could be a little lucky This is this is a little conservative what I've indicated here, but still it's it's roughly correct It can be discovered up to around two and a half TV In the super duper asymptotic future of the LHC, okay But we also see some other we also see some other Interesting things that so let's say it's the end of run two If it's the end of if it's the end of run two and we've only excluded bluey nose if we've only excluded them then Then so we've excluded them up to here. Okay Then we're not going to discover them. We're not going to discover them Until perhaps we get to the high luminosity run of the LHC. Okay, so all of this is just to Repeat in a little more qualitative and quantitative detail of the same mantra over and over the biggest Gain is with going to higher energies at the very beginning after that. It's more painful gradual increase with extra luminosity and And the five sigma discovery there should be harbingers with lower sigma hints and indications but This is why this coming year is Year or two is by far the most exciting period and then after that Of course, it's still possible that will make the discoveries, but it don't it but it gets it gets more and more different Okay, so By the way, can you guys hear me? Okay? Yeah Well, I want to say about the LHC and now I wanted to turn to the second topic I think that I've spent quite a bit of time on the LHC. Don't worry I won't make you sit through the following on 49 Transparencies in a detail, but I want to tell you a little bit about it so So this is the it's the next See These machines take, you know, 25 30 years to think of conceive design plan and build And so a lot of people around the world have been thinking about what the next step After the LHC will be of course for a long time and it's remains a very Very good exciting important possibility Is to consider electron positron collisions at a linear collider and Japan is thinking about building a linear collider And that's that's that's that's very very important But ultimately if we want to get to the energy frontier again we ultimately want to get to a And to another big circular collider that can that can collide protons at let's say around a hundred TV And so that's what people are starting to talk about now are great big circular colliders There the circumference of the circumference of the LHC is around 27 kilometers The circumference the circumference that people are talking about here would be around a hundred kilometers And you could you could collide One thing that you could do very much like the Program at CERN is you could actually start colliding electrons and positrons in this In this tunnel at a center mass energy of around 250 GeV And you could do that to produce millions of Higgs particles and study the properties of the Higgs in great detail And then you could go to eventually in the same tunnel to collide protons At an energy of about a hundred TV or so, okay? So just so you have some idea of the numbers Right now the LHC like I said, that's 27 kilometers and the central driver the main driver of the size and cost and all of these things of These machines especially for hand-drawn colliders are the magnets that you need to bend the protons around, okay? Now at the LHC they have magnets that have around eight Tesla of strength So if you go and you build a hundred kilometer tunnel And you take the magnets we have from the LHC right now we shove them in the hundred kilometer tunnel Then you will have yourself a collider. That's a little more than 50 TeV Okay, so if you really want to get to a hundred TV Then you need to make the magnet stronger now fortunately the people who spend their lives developing these Super duper high-field Superconducting magnets They have it on their agenda To make these much higher field magnets actually right now In America at Fermilab and at the at LBL people have magnets that are around 11 and a half Tesla working already and this community of people believes that on the 10 or 15 year time scale they can get 15 Tesla magnets In fact, they even talk about eventually with the more ambitious technology getting 20 Tesla magnets So so going from 8 to 15 seems seems like a conservative bet That on the 10 or 15 year timescale the 15 Tesla magnets will be available And if you put those 15 Tesla magnets into a hundred kilometer tunnel you you get yourself a hundred TV proton proton But those magnets aren't going to be ready tomorrow or even probably 10 years from now And that's another motivation for just starting to build a hundred kilometer Tunnel somewhere starting to dig And when you have it to first run the C plus a minus program because you can Study everything about lots and lots of important things about about the hates while you're waiting for the magnets to be developed And to come up to the point where you can then in the same tunnel use them to do proton proton So that's the that's the thing which is being talked about. This is being very seriously talked about at CERN Where this program is called goes under the general rubric of the FCC for future circular colliders there's actually just a little earlier even This week there was a big meeting in Washington where they were talking about their their plans for doing this And it's also being seriously discussed in China Where the project goes under the name of a CEPC for circular electron positron collider for the E plus a minus option and SPPC for super proton proton collider for the for the hundred TV option and so so this is This is really something which is which is being taken quite seriously by the by the international Part of this community now. There's a lot of exciting about it for obvious reasons. It's the I think a facility like this would be the 30 40-year future of the experimental part of our field be very important So I just want to tell you a little bit in the time I have left a little bit about some of the motivations for doing this and The fact that I want to take here, obviously if in this coming run of the LHC We discover some new particles. Let's say we discover the one and a half TV 1.6 TV Gluinos Then it's completely obvious that we're going to want to keep going and study them and so on and I'll say it a little bit more About that but but essentially independent of what the LHC does or doesn't find We have a need to continue and and that's not just for it's not just because we should keep going Explore et cetera all that's true But it's for more more specific reasons We already know Given that we've seen the haze at the LHC and given that we haven't seen anything else yet We already know no matter what the LHC sees That there are questions that we're not going to get important questions We're not going to get the answers from from the LHC and so we're absolutely going to have to keep going and these two Facilities are actually complementary To each other for doing that but Let me just say that In in in having the rest of this discussion, I'm going to focus on the possibility That in fact the LHC won't see anything other than the haze and we'll see nothing We'll just see the haze and nothing else And this is the case that that many people in our field for a long time have been I think very stupidly Calling the nightmare scenario And saying I'll be so terrible if we don't see new particles other than the haze Well the field is over, you know Why should we keep going experimentally? We'll never convince politicians to build another machine blah blah blah There's there's there's some subset of people who said words like that for many years I think it's it's it's it's really quite quite silly And I just want to spend a few minutes Talking about that that the attitude Because this comes from a basic attitude that thinks that that new physics is equated with new particles and It's true. It's true that in the period of great discovery in particle physics From the from the 60s the sort of last era that a lot of people think back to is the as the glorious period of the Subject that there there were many new particles that were discovered and the new particles told us a lot about about the structure of fundamental physics leading to the standard model but But new part of but new physics has not always met new particles and in fact the biggest Conceptual changes that we've been driven to in fundamental physics, you know But the standard model is not one of those things the standard model is a spectacular accomplishment but took place completely within the rubric of a structure of The of the revolutionary structure that was handed down from the first part of the 20th century in relativity and quantum mechanics Those were the really big humongous revolutionary Developments the standard model is relatively speaking a detail compared to that And and the really big revolutions were not associated necessarily the discovery of new particles That's a new physics is not always mean new particles What new physics really means what we really care about our new phenomenon, and we care about the new phenomenon because They're associated with new principles That's what we really care about if it happens that those new phenomenon and new principles come in the form of lots of new particles Wonderful, but they have not always come in that form just to give you an example of a extremely important null result of not seeing particle or anything having a Being hugely significant The fact that people looked for drift through the ether and they didn't see it That wasn't looking for particles that was looking for a phenomenon and they didn't even see it But not seeing it was an enormous deal of knowing that that there isn't an ether was was one of the most Profound things that we could have discovered experimentally About the way the world worked 100 years ago. So now because of So so with this with this attitude, I think that In fact, the Higgs itself is really new physics Not because it's the particle that we didn't expect or didn't think about Beforehand we did But in fact, it's an extremely unusual particle. We've never seen anything like the Higgs before We've never seen an elementary spin zero particle and That's that's what we've seen with things in fact, they're very good theoretical arguments that we shouldn't have seen Point like spin zero particles The arguments revolving around fine-tuning in the hierarchy problem. There are analogs of this argument in condensed matter physics That that work and explain why it is that we don't see anything that looks like the Higgs in in Ordinary in the long-distance aspect of field theory of ordinary Materials we can engineer all kinds of quantum field theories in the lab And that's matter frames can engineer all kinds of exciting and interesting quantum field theories in the lab They can have things that look like gauge field They can have things that look like fermions and pyro fermions, but they never have anything that looks like the Higgs They don't have these elementary what look like point like spin zero particles in ordinary, you know zero temperature materials And there is a good reason for it Now there's a good reason for it that that Ken Wilson figured out that that it's unnatural for a scalars to be light You have to finally adjust the properties of the material in order to get a very light scalar and unless there's someone doing that fine adjustment We don't expect to see light scale whereas the existence of fermions and gauge fields is Can be natural the ultimate reason for this the ultimate reason why there is fine-tuning associated with making scalars light, but there isn't fine-tuning associated with making Photons or spin spin one particle just been half particles light is that there's a discontinuous difference between the number of degrees of freedom for particles with spin if I take a if I take a photon the Between masses and massive particles if I take a photon The massless photon has two degrees of freedom the mass of photon a massive spin one particle has three degrees of freedom And that's why you can't just little interactions can't make a massless Spin one particle into a massive spin one particle because you can't change the number of degrees of freedom discontinuously Exactly the same thing is true for everything else for pyro fermions But spin zero particles is different because there's no difference in degrees of freedom between spin zero particles First been zero particles between masses and massive. So that's what's so strange About about the haves in many ways. It's the simplest possible particle. We could have discovered It has It's been zero. It has no charge all it has is mass But that very simplicity is what makes it so strange and what and what makes it the And is why we've never seen it anywhere else in physics before and Certainly not just in my view in the view of many of us understanding why we got the things to begin with is a harbinger of Really profound new principles at work in in in the quantum vacuum We there's This basic logic of effective quantum field theory That that what that's been so spectacularly successful not just in the standard model But everywhere else in in the physics of many body systems This is a logic that would have led us to believe that we can't just see a lonely Higgs it should come along with lots and lots of extra particles super partners Or we should see the Higgs composite or has some of the structure So either we'll see that which is wonderful or we won't and then we'll know that there's there's something wrong in this in the calculus of the argument That that we've been using that's been very successful everywhere else. So so in that sense that The Higgs is actually is by itself new physics It's new in the sense that we've never seen anything like it before and we have to study it very closely So let me Just then tell you at least in this lens through this lens what what a Pussy minus Higgs factory and a hundred TV collider would do and what it would do Just about the columnist more about About the properties of the hits so first As I mentioned we've never seen a point like scalar before it looks like roughly speaking the Higgs everything we've seen so far It's consistent with it being with it being point like but the LHC won't will only give us a fairly fuzzy picture of of the Higgs so So and what I've drawn here is not is a cartoon so so known as the size of the The Compton wavelength of the Higgs there is one over the mass of the Higgs and if the Higgs was a completely composite object Then then there would be form factors in its couplings the ordinary particles And we would already know that We would already know that just like we knew from the fact that the G factor for the proton is quite different than to that the proton had a structure on a scale comparable to its mass if the Higgs had a Substructor on a scale comparable of its mass. We would have known that already from the LHC its couplings to z's and to Other particles would be order one different. It's not order one different but But through the entire running of the LHC We're only going to measure many of these couplings so that 10 or 15 percent low And so we're not really going to get a picture that it's particularly point If you really want to see that it's point like you want to you want to see that it has point like couplings to all the astatomotor particles for that you need to build the Higgs factor and And the the point here isn't so much that the number of Higgs that you produce the LHC will produce tens of millions of Higgs particles But the problem is that it's producing when a messy environment of a hadron collider and it's hard to make precision measurements in that way However at an epoxy minus machine you can also produce millions of Higgs particles, but study its properties In great detail in a very clean environment. And so this is the picture that we will come to so between a kind of fuzzy picture the resolution will improve by 10 to 50 to in some cases a hundred times better Than the the LHC So that's that's the purpose of building an E plus E minus Higgs factory and by the way some of this physics will also be done by the linear collider, which will also be good at measuring These Higgs couplings are for the particular coupling that I'm drawing here of the coupling of the Higgs disease The linear collider is not quite as good as a circular E plus E minus machine just for detailed differences that it's hard to get the luminosity to the same level at for these collisions at a Linear collider, but still this is basically a part of the physics program also for the linear collider and Now another crucial feature of an elementary spin zero particle is that An elementary spin zero particle Can do something that we've never seen another elementary particle do which is it can interact with itself We've actually never seen self-interaction self interaction between a single elementary particle before You might think oh, but come on blow on self-interactive each other. We have the non-abillion self interactions. Yes That's true, but it's never one particle with itself. They're always changing color. Okay, or you might think well But we know that gravitons have a self interaction. We know that this non-linear self interaction between the gravitons is Is very important Yes, it's true, but it's not but there there's a change in helicity So we've actually never seen the most basic process you might think of in quantum field theory Which is just a self interaction of three things with each other We've never seen it before and the Higgs is the first particle which gives us an opportunity to see that most basic process of all So in order to see even whether there is a self interaction of the Higgs We won't do that at the LHC the LHC won't even tell us if this process exists But if you go to a hundred TV collider You can produce so many Higgs that you could actually not only see this thing, but measure it even at the five percent level so that's So that's that's part of the the physics motivations and purpose of these of these of these machines And that's a kind of the the physics that's guaranteed to be studied and understood is to put the Higgs under this mic microscope see if it looks elementary and see if See if it has its own Self interactions of course on top of that. We're going to measure Especially been going to the hundred TV collider We're really going into Another big leap in energy a factor of seven From what I told you in the previous part of the talk You see why those factors are seven or a humongous deal, right? Because now the cross-sections are going up by factors of Thousands or tens of thousands the mass reaches going up by about a factor of five or six relative to the LHC So it's a huge gain both an overall reach and in and in overall rate That's what we go into totally new territory and look for for physics that that that might be there physics that we just may have missed at the LHC and Also, even if there is physics that that we see at the LHC. So let's go back to that example of the One and a half TV. We know so let's say that the way it was really sitting there at one and a half TV We'll even discover it this year. Yeah, fantastic But that means that in the entire course of running of the LHC will maybe make a few thousand of them Okay, so that's actually not enough. That's plenty enough to know that's plenty enough to know that you've seen a new particle no problem But it's not enough to know that it's a gluino It could just be some color adjoint You won't know that its couplings are consistent with those of a gluino So if you really want to learn these not just produce the particles but learn what they are even if we're Fortunate to produce them at the LHC then it's not a question of meeting higher energies to access heavier particles But it's a question of producing lots of them. So that one and a half TV gluino will produce a few thousand of them at the LHC and will produce a hundred million of them at the hundred TV collider, so it's just an enormous difference and On so and that gives the huge gain and rate on the other hand The actual reach for producing the particles The reach for producing gluinos at the LHC as I told you goes up to maybe two TV two and a half TV three TV the reach for gluinos at a For the same gluinos at a hundred TV collider will go up to 15 or 20 TV So there's a huge gain about about a factor of five or six as you go As you get this big gain in that energy so So there's the guaranteed physics of studying the properties of the Higgs and And there's of course the sort of going into into the big new frontier Just to explore it and see what is there so Yeah, so I think I'm not going to I'm not going to have time to go through these things in more detail Um, maybe I can just make one point. So I'm just going to pick and choose from a few of these things Just just just to make one point about the importance of measuring this self interaction of the Higgs There's a very basic question We discovered the Higgs So so we know what the small oscillations around the So so so we know what breaks electric symmetry the expectation value of the Higgs breaks electric symmetry And so we've seen these small oscillations around the minimum of the potential. That's the excitation. That's the Higgs Actually from the LEC. We have no idea what the global picture of the potential looks like Okay, we don't know if it looks like the red picture. We don't know if it looks like the green picture I mean experimentally. We don't know what it looks like and You might wonder well, of course the standard model tells us what it looks like it looks like The it looks like the Landau-Ginsberg picture looks like m squared Higgs dagger Higgs plus some quarter coupling Higgs dagger Higgs square Come on, why would anyone picture? Why would anyone question that simplest possibility? Sure, maybe we haven't established it experimentally, but it seems completely obvious that that simplest possibility is going to be right well Um that simplest possibility that was motivated by the connection with Concentrate matter physics ultimately After all came from Landau-Ginsberg thinking about the face transitions It's exactly that same logic that leads us to think that there's a hierarchy problem. It's exactly that logic that I Mean after all, why do we think this is true because we say there's physics at some at some high energy microscopic scale We should just write down an effective field theory and we should write down all the operators in the effective field theory You know compatible symmetries and so that argument is exactly the one that tells us that the mass should not be too far from the ultraviolet cutoff of the theory, okay, so so So there's only a hierarchy problem to begin with or even though issue only arises If we actually know the potential has this form But suppose that we went out we discovered experimentally that actually the potential didn't look like that and instead of balancing a quartic Against a quadratic instead of a quartic. Maybe it was a balancing a quartic against the sex stick like in this second line Or maybe the potential doesn't even isn't even well approximated by polynomial Maybe it has this form that isn't even analytic like Like Higgs to the fourth log Higgs square This bottom form is sometimes referred as the Coleman-Weinberg form for the for the for the for the Higgs potential If we knew for a fact that this is what electric symmetry breaking look like It would it would completely change the way we we think about all the problems that we've been obsessing about for a long time it would completely undercut the The Landau-Hinsbury philosophy it would throw the hierarchy problem out the window we'd have to come we'd have to well For one thing it would give us some immediate indication that there is physics Talking at least to the Higgs at a scale of not far away, but also we'd wonder is what was wrong with this original logic to begin with So what I want to say is that this simplest possibility that comes out in the standard model again The very simplicity is exactly what leads us to believe that we shouldn't have just seen a haze Alone far away from the ultraviolet cut off of the theory. So this is not an innocuous assumption And therefore it's absolutely crucial to test it experimentally So what is the leading difference between all of these possibilities as far as the LHC is concerned We will not know if it's the top or the second or the third No measurement that will be done of the LHC is going to distinguish between these possibilities, and we know that right now The reason is that the leading way that these possibilities differ is in the strength of the self-interaction of the Higgs That's because when you expand the potential around the minimum And you look at what the cubic self-interaction is of course it's going to depend on on on the precise shape of the potential and They can be order one different from each other. So for instance in the second case The strength of the triple Higgs coupling is seven-thirds times bigger than the standard model It's a pretty big difference in the bottom case. It's five-thirds times The size in the standard model so it can be very different than what it is in the standard model But we will not know at the LHC and so this is one of the reasons as I said one of the One of the guaranteed bits of physics that that that we will get in this case from the from from going to a hundred TV collider So, let me show you another thing. Sorry going back now. So here is a Picture of the level of precision in the couplings of the Higgs that are going to be reached Now in this case at an E plus E minus Higgs factory versus what we will learn Even asymptotically with the all the data will gather at the LHC the LHC is in gray And what we'll get from the Higgs factory is in red and so you see that across the board There's there's a factor of 10 20 30 sometimes 50 increases in the in The precision that we're going to reach that these guys at the bottom here is these Kappa B is the is the Precision to which the coupling of the Higgs sub-bottom for to be measured This Kappa Z here is the most impressive of all which is at around the at around the the point point 1% level and So but in almost all the cases the level of precision is Is less than a percent and a clear order of magnitude and sometimes better improvement Relative to what we'll get from the LHC so that that indicates the that indicates the Just the power in probing Higgs physics and let me just show you one more Example here. Yeah, so here's This is showing The the just the improvement in overall reach in going to a hundred TV Here you're looking at the five Sigma discovery of super partners At the LHC, which is this black band here Relative to what we might imagine at a hundred TV collider, which is this green one Okay, and so you see that this is what I was telling before Louis knows we can we might see up this sort of two two and a half TV down here But with a hundred TV collider here it can go up to 10 13 Sorry a 10 11 TV for discovery and almost up to 15 TV for For exclusion that's if you're just directly pair producing Louis knows if you have more of the supersymmetric Spectrum then then you get these numbers going into the 20 TV range that I mentioned before Again compared to what we have down here from the LHC So there's roughly a factor of five increase across the board in going from the LHC to a possible hundred TV client and There there even some some quite dramatic cases in various versions of Interesting versions of supersymmetry the first two generation Super partners can be Kevin they can be a 10 20 30 TV We'll completely miss them at the LHC even if we produce the other particles. We'll make the Louis knows for example We'll miss them at the LHC But one of the but the but the gluino could be still light. We could make the gluino Or we might we may or may not make the gluino. Maybe we slightly miss the the a gluino and it weighs two two three TV whatever Well, one of the most one of the most promising channels for producing Superparticles even at the LHC, but also at a hundred TV is Through this diagram that I've shown here called the associated production where you have an up quark And the glue on coming together through a gluino in the tea channel and producing a gluino and a squark In this case if the gluino is light But these squarks are I mean light means two or three TV But the squarks are at the are 20 or 30 TV You could still produce them at a hundred TV collider in fact There's a reach for producing squarks almost up to 35 TV in association with a light gluino At a at a hundred TV collider. So those are just some illustrations There is and finally In questions that have nothing to do with the naturalness But are just more directly motivated by the production of dark matter particles. Let me just Show this summary plot Here's a very qualitative point that Dark matter could be weakly interacting particles weakly interacting particles Annihilated with each other in the early universe so that only a small amount of it is left over today and makes up the Makes up the dark matter Famously if you ask what mass to these dark matter particles need to have if they are indeed interacting with the weak interactions What mass do they have to have in order? To be dark matter the mass that they need to have is somewhere near the TV skin in the fact the formula This is something worth remembering is that if the effective interaction strength of the G squared is around Normalized to be around point three That's a reasonable strength that we have for the couplings in the standard model But the mass of the dark matter particle would have to be around two TV So this is very important dark matter is not guaranteed to be even if it's a win Even if it's a weakly interacting particle, it's not guaranteed to have a massive a few hundreds of TV In fact, if it's annihilating through just the ordinary standard model gauge interactions if the if it's if the Amount of it left over from the Big Bang thermal relative abundance Comes from those annihilations its mass would have to be one or two or three TV not a few hundred G and We've known that for a long time Possible for it to be hundreds of GB, but only in more and more if there are many more particles around when the more complicated Scenarios But if it's just an electric charge particle It's an electric doublet or an electric triplet and the only interactions involved in its annihilations are The standard model interactions then the mass would have to be one or two or three TV And that's just not accessible to the LHC. The LHC is good for making colored particles One two to three TV, but uncolored particles may be from two to four hundred GB as I said before So that's something else that we know ahead of time that the LHC is just not going to cover Even the meat of the parameter space for what would correspond to these simplest pictures of what went dark matter could be But if you go to a hundred TV collider All the rates go up by the factor of a thousand Hundred to a thousand and so If you want to have a powerful probe of one or two or three TV electric particles The hundred TV proton proton collider is a thing which is ideal for that. So you do get a factory, you know huge rates for producing Electric particles and that's sort of summarized in this in this table But there is a reach for producing Dark matter particles again in precisely the ranges that we are talking about and The top two cases we know and Higgs you know that really means a Really means an electric triplet and electric doublet. Those are particularly Simple and well-motivated possibilities. If you have an electric triple particle We know ahead of time. It's masses gotta be around 2.7 2.8 TV for it to be dark matter If it's a if it's a electric doublet like a Higgs you know We know it's max. It's got to be one TV in order for it to be a Thermal relic dark matter and of those possibilities are are almost completely covered by the hundred TV collider so and of course more interesting possibilities are More more interesting things are possible and everything makes them actually easier to see The reason is that in these most minimal possibilities the way you look for the dark matter. It's still pretty it's still pretty direct You can't just collide To partons and produce two dark matter particles and not see anything There's no there's no there's no signal for just nothing. So so what you have to look for is is the final state or initial state radiating a jet So you can look for jets plus a single jet plus missing energy or a photo or photon plus missing energy and Those are the those are the events which you can use to look for this Dark matter in the case where you're just directly pair producing the dark matter particle That's the most difficult case and even in that most difficult case You can basically cover it with the hundred TV collider if it's more interesting if you have a bunch of these particles If there's a sector of electric particles and you produce a happier one in the case to a lighter one Then things are much much easier and but any case you See from these plots just from those axes that it's the TV scale that's showing up everywhere here And so there is a robust probe of electric particles up to up to a TV all right, so so I'll just finally show you just just just as I said before this possibility is being taken seriously Around the world now and the proof of it is that There are pictures like this. These are pictures that particle physicists love to see of maps of the world with big circles on Okay, so and here's a picture of a of the area around around Geneva and this is there's the LHC as you see drawn and Here's a picture of where they're thinking of putting this 80 or 100 kilometer long tunnel to host this facility It'll have to go under the lake which is which will cause some complications, but they'll go manage to do it I'm sure and here's the analogous picture in China so So there's an area. I'm told it's It's it's 300 kilometers northeast of Beijing apparently it's right next to a beautiful beach and And and It's very pretty and I'm told there's no pollution But but there there there's a picture here's a 50 kilometer tunnel and a hundred kilometer tunnel Plenty of room here in Qingwan Dao and actually strong interest and support from the local government to even help build deal with all the infrastructure facility and and and so on so So this this project is being strongly thought about by the by by the people at CERN In China, it's going to be Officially proposed to the government this year to the Chinese government this year and they're going to make some decision about it this year Now they're likely not going to make a decision about whether to fund the whole thing on the Right away, but they're making some decision about whether to fund five years of the serious R&D effort And I think the sense of many people is that if they if they if they do decide that they're going to Go ahead with the R&D. That's very that's very strong very strong serious indication And support for the possibility that it will actually happen but anyway, that's That's that's that's that's the decision that's being made this year So we're going to have some we're going to have some idea about Whether these machines will really become possible. I think sooner Rather than later and as I said part of my motivation for talking about all of this here Is that if these things happen? This is the machine for your generation of people and I think it will be enormously exciting and and and you should find it exciting and Not only hope that it comes to fruition, but but if it starts coming together It's your generation of people are going to have to think about all the great things that it could do so Final thing that I want to talk about Whenever anyone talks about these big accelerators You always hear oh my god. They're so expensive. How are we going to convince politicians to do these things and so on? In my experience every time someone talks about having to convince politicians of something It's it's nothing to do with the politicians. They're actually they can't convince themselves Politicians have no idea what's what's interesting or isn't interesting science and this and that They have to rely on us to tell them what we find important and make a case for why we want to do what what we want to do So so we should never judge ahead of time what their Responses these things are in fact, it's our job to tell them what their response should be and then decide whether you know our whether people want to actually go go ahead and and Give up the resources for doing this sort of thing But if you want to know how much of these things cost they cost 10 billion in whatever your favorite units of currency But while that might sound like a lot, this is a great great plot This is a great figure. It shows that accelerators have always cost roughly the same amount And they cost always roughly 10 to the minus 4 of GDP. So for example the LHC Costs around 3 10 to the minus 4 European GDP lap cost around 2 10 to the minus 4 European GDP this this figure was made by my friends in China talking about the cost of the project there the in fact China in 1984 built a Built a very small electron positron accelerator that they have in the Beijing still on that cost 10 to the minus 4 of Chinese GDP in 1984 and Now now the electron positron Higgs factory that they're talking about would be around a half 10 to the minus 4 The proton proton collider will be around 10 to the minus 4 So the cost is it's big. It's it's 10 to the minus 4 of GDP, but it's always been that big We're not talking about anything which is particularly bigger now than than than it was before So I don't think there's an issue of cost or will or anything like that. It's really We all of us have to think about How excited we are about about the physics and tell Other people who make decisions how exciting the physics is and then we'll see if If humanity wants to keep this 100 year quest going, but I'm pretty optimistic that that these things will actually become Well become a reality. So that's all I wanted to say I think This is a very different lecture than the other ones that you've been That you've been hearing so you all know that it's an incredibly exciting time in in all these incredible Formal developments that are going on in in our incentive quantum field theory and string theory I think in that direction There there's there's so many remarkable things going on that to me it feels like an incredibly exciting time Something big is going on and it hasn't been Fully digested and and and understood and no one knows what the big picture is yet, but but But there's obviously something deep and important going on and it's also Fantastically exciting period for expert for experiments as I hope to have convinced you the next few years is probably the most important of the Entire a life of the LHC at least when it comes to looking for physics beyond the standard model And even the longer-term Future of the experimental part of the field and thinking about the big accelerators It's something something something there something that we can something we can think about and hope actually happens and If it does happen these things aren't infinitely far away, you know that the These proton-proton machines could start I mean if it happened at Sturm that could start in the in the mid 2030s the Higgs factory That they're talking about in in China If everything goes according to plan that would be starting by the late 2020s 2027 2028 If we have a linear collider in Japan, it would start even earlier than that So we would start getting somewhat earlier than that So we start getting information about about about the Higgs there so so there's things going on on on All fronts and I'll just end with one just small piece of one small comment that This is a this is a school on on more formal aspects of quantum field theory and string theory But but really there's no such thing as formal theory and phenomenology and this part of cosmology and this and that in our field Especially work for theorists and fundamental physics. There's just one subject. There's one big subject. It's called theoretical physics and and with the with the with the broad and deep understanding of The basics of a quantum field theory you can do anything you want and move around from field to field and do any damn thing You want so and I think that's actually going to be needed and perfect for the era that that we're in There's all sorts of things going on purely theoretically in connection with experiments With colliders with dark matter experiments with the cosmological observations So it's really a perfect time to think broadly, but don't be a dilatant Don't just jump around from topic to topic learn the basic Fundamentals of quantum field theory as deeply as you can and and then and then Move around to wherever your Your your your interest take you because this period we're in I think is absolutely perfect for broad and deep youngsters to make an enormous impact. So All right, that's all thanks a lot. Thanks. Thanks, Nima. Are there any questions? Yes with the available data from the CMS and Atlas teams and how much they agree With the Higgs value How much they agree between them? Oh, I mean now now that there's that earlier on there were little there were little Little discrepancies in the mass of the Hagen so on but everything lines up perfectly right now And they agree in a single peak or yes. Yes. All right. I mean all of that stuff Look early in any discovery And this is not just with the Higgs if you go back with the everything especially for particles that have that are somewhat expected Two things happen first the the the cross-section With which it's discovered tends to be bigger than it actually turns out to be And this is a combination of luck and also being very aggressive by experimentalist because you're you're you You start seeing seeing something so that's Also physical fluctuations happen. So so when when the Higgs was first discovered that it's rate for For being produced into Kang into into two photons Maybe a factor of two bigger than the standard model. So a lot of people are like wow factor of two This is a huge deal, but I think you know anyone who sort of follows the history of particle physics knows that that Directly at discovery level these factors of one and a half to Flood around and eventually Converting and of course right at the beginning there was a little difference between the peaks all that stuff is gone That there's a that the Higgs is 125 and a bit GV and and it's discovered at seven sigma And both experiments basically Thank you any other question on Can ask what's a particular reason to choose 100 TV TV or like a 50 TV enough or That's that's that's a very good question. I think I think the the correct answer right now is that a hundred TV is a nice round number It's it's sort of historically been the case that that there are Increases of about a factor of seven in energy from one hadron collider to the next but but But that's that's not a good reason. So right now it's a right. It's a nice round number and What really needs to be done is for people to more carefully study what the physics potential is for 50 TV 100 TV 150 TV and see what it is that we we really need Okay Now and of course many of us have spent the last year doing a lot of studies of this sort Particularly for the for the effort in in China this last year There was lots and lots of effort in China around the world amongst amongst the collider physicists Thinking about this this kind of question It was more urgent because these studies needed to be done in time in order to make a case to the government this year So but any case so many of these preliminary studies have been done and I think I think a hundred TV is looking Like it's more justified now Because for example, but let's just let's Let's talk about them the Let's talk about the case of Dark math, okay, so you want to you want to really robustly probe and an exclude if it's if you don't see it The possibly that there's a lecture week charge particles who are in the dark matter with a hundred TV You're just doing it. Okay, and even there's a there's some there's still some little gaps With 50 TV, you would be covering. I mean, but it wouldn't be little gaps with 50 TV You'd be covering, you know half of the parameters space, but not not not really the whole thing So But but other than that But I think you know, we need more more more studies of that of that sort In order to have a clear idea But my guess is that it'll is that the sort of optimal thing will end up being not far from a from a hundred TV Maybe it'll be 80 I suspect 50 will will not be Well, I mean 50 will leave you wanting for a number of these questions I didn't have time to talk about this But let me just say that that we don't I mean you might wonder how do we know what what there is out there? So we don't know what there's out there. So we have no idea for what energy we should be gunning at It's true It's it's true that if we just see the Higgs and nothing else at the LHC that we won't know what is out there But there are well-defined physical questions an important physical questions that the that have to have an answer involving particles that are accessible To these machines and so for example that question is what is the shape of the electric potential? That is something which That that is something that in order to get the answer to that question in order to know whether The shape of the electric potential is qualitatively different from the one that we think of In the standard model if it is qualitatively different the particles that are responsible for making quality different They can't be at they can't be at a million TV They have to be at the TV scale if they're going to affect the shape of the potential and they can't be two weekly couple to the Higgs Otherwise again, they won't affect The story at all. So so if you want to ask the question, you know, if there are particles that affect the structure of the The electric phase transition so strongly is they even change it to order change it from second order to first order That's something that will have no idea about at the LHC But let's say you want to settle that question. Is the electric phase transition first order or second order? You want to you know robustly probe and settle that question that gives well-defined targets of Couplings strengths to measure to the Higgs masses to look for of new particles at the high energy collider and You know more detailed studies like that are going to be needed to get the answer To get the sharp answer to question But but I think what we're seeing in all these preliminary studies is that a hundred TV is not is not like gravy And you could already do with 70 hundred TV just seems to be just about what what what you'd actually want Thank you. Any other question? Okay. If not, let's thank me by getting