 OK, I guess we can start. Sorry, everybody, for the delay. We have a small inconvenience. But finally, we are here. Welcome to the season six of these Latin American webinars on physics. I'm going to be the host, Roberto. And the speaker of today is a very important physicist. He is John Ellis, that he was kindly wanted to give this webinar. And after a lot of problem with the computer, we make it. And we're going to make a double connection via Hangout and Skype. So it's going to be a little bit messy. But all the information is going to be here. So first of all, we have John. And then, John, if you can say some few words so that people can hear you, John. Yes, hello. I hope you can all hear me. I'm speaking to you from King's College, London. I should apologize for the technical problem. I don't know what the problem is, whether it's at King's or whether it's Google. But anyway, I'm very glad now to be with you. Yeah, very good. So for all the people that are following us in YouTube, John Ellis is a world-class physicist. He had been, I mean, he did his PhD in Cambridge University and after some postdoc in his life. I'm Fermilab, sorry. Anyway, he spent most of his career at CERN around almost four decades. And now he's at King's College of London. So John, his pressure is very nice to have you here. And you can start your presentation when you want. Let me just share my screen. And oops, where is John? I lost your screen, John. Sorry, one second. OK, if you can share your screen, now you can present. Yeah. I'm showing my screen. Do you not see it? And don't see it. If you can share it again, just stop and restart the screen share, we can. OK. We are having some dots from Skype, John. So it seems that the, OK, it seems for the moment that the screen is not, I mean, we are still having some technical problem. We are going to solve the problem now, one second. I don't know if you can. We are still waiting for the connection. Seems that also he's having problem from, seems that the reason of the problem is actually related with the firewalls in King's College. So for the moment, we are still trying to connect. If it is not possible, yeah, there is some. I don't know if you can see the connection from my side, because I'm not sharing the screen with you guys. But you can see that we are still waiting for his connection, his video. Let me just try to call him again. If this guy allows me to do it. OK, seems that it's what is happening in the live streaming. So if you give me some seconds, we are going to fix it again, as it's all the time it happens. One second just to have a small conversation with John, and we're going to be live again soon. OK, we are going to be soon again. Sorry, one second. For the moment, I leave you with the screen. Roberto, can you look at the chat? OK, everybody, we're back. We fixed the problem. This is the next step of the live streaming. So if John now, if Skype allows us, then it's a conversation between Google and Apple. I'm Microsoft sorry. So if everybody can see this, we're going to start. Yes. So John, the stage is yours. So Roberto, how long should I talk? Much as you want, but less than 45 minutes, 40 minutes. It's OK. Yeah, OK. So again, thank you very much for the invitation to give this talk, and I apologize for the technical problems. So let me start straight away with this inspirational picture, which was taken somewhere in Latin America. So you guys should be able to tell me where it was taken. Anyway, particle physics today, I think, is largely dominated by the recent discovery of the Higgs boson. And here you see Peter Higgs, it's a picture taken in 1965, when he was working out some details of his theory. So I think with this audience, I don't need to remind you about the structure of the standard model. Here in the bottom part of the slide, you see the standard model Lagrangian. So the first line describes gauge interactions. The second one, how those interactions work on the fundamental fermions. And the two bottom lines, that describes the Higgs sector of the theory. So the third line, the car interactions that give masses to fermions. And the bottom line, the Higgs potential, and the mechanism for actually giving masses to the gauge bosons. And I think it's worth remembering that there were no direct tests of those two bottom lines before 2012. One of the things that I'll be discussing is how far along we are in terms of testing that. And where we can go in the future. So the next slide shows you what's often called a stairway to heaven. And this is a summary from Atlas of the many, many measurements that they have made of standard model purposes involving QCD, electric gauge bosons, jets, and of course, the Higgs boson. And of course, although we fear this can be very proud, I'm sure that we would have preferred it, that they find some significant discrepancy from the standard model, but none have showed up so far. OK, so let's focus in now on the Higgs boson. And here in the top half of the slide, I show you the couplings of the Higgs to vector bosons on the left and to fundamental fermions on the right. So coupling to bosons are actually discussed in quite some detail by Peter Higgs in the paper he wrote in 1966. And I recommend that to anybody with a historical interest. As far as I know, the couplings to fermions were first noted explicitly by Stephen Weinberg in 1967. So my own interest in the Higgs boson started in 1975, when together with Mary Dayar and Dmitry Novolos, you made the first, I think, attempt at a systematic survey of what the properties of the Higgs boson might be. Now, of course, back in those days, the Higgs was regarded as something very speculative. You know, the senior gray-haired physicists regarded it with suspicion. And for that reason, we were a little bit tentative when we said that we do not want to encourage big experimental searches for the Higgs boson. We did want people to know what it might look like in their experiments. So that was 1975. The next slide comes from 1984. This is the first physics of the LHC workshop held in Lausanne. And I got the job together with Graciela Gelmini from Argentina and Henry Kowalski of reviewing the possible new physics that you could do with the LHC. And of course, we call the emphasis on the Higgs boson, as shown in these two diagrams, but also on supersymmetry, which I will return to later on. So continuing with the Higgs boson, this slide shows you the dominant production mechanisms for the Higgs boson at the LHC. So the top line, the dominant production mechanism is gluon-gluon fusion to make a Higgs to top loops. Then you've got, for example, in red, vector boson fusion, massive vector boson fusion. In green, you've got associated production with the W or Z. And then in purple, you've got processes for production in association with the top hook, either a TT bar pair or a single top floor. So we should consider ourselves very lucky that for a Higgs boson weighing 125 GeV, many of these mechanisms are accessible to experiment. And in fact, most of them have now been observed. In fact, just yesterday, there was a seminar at CERN by Atlas where they reported four sigma evidence for TT bar Higgs associated production. Okay, so I expect that most of you are familiar with the large Hadron collider at CERN, so I won't dwell on it. Let me go directly to the measurements that have been made at the LHC so far. So in this picture here, you see the measurements of the Higgs mass from a combined analysis by Atlas and CMS. And you see that already with those run-run measurements, they got an accuracy of about two per mil on the mass of the Higgs. And I might mention that subsequently, both Atlas and CMS have come up with measurements based on run-to data. And I highlight here the measurement by CMS of the Higgs decay into ZZ star into four leptons, which already has a smaller error than the overall uncertainty in run-one. Now, of course, measuring the Higgs mass is important because it enables us to make precision tests also with Higgs couplings. But I like to spend a bit of time discussing another important aspect of the Higgs mass measurement, which is its importance for the stability of the electric week vacuum. So on this slide here, I discuss the renormalization of the Higgs self-coupling in the standard model. So the Higgs self-coupling lander renormalizes itself. Now that renormalization has the effect of increasing the self-coupling lander as you go to higher renormalization scales. On the other hand, in the standard model with the measured values of M Higgs and M top, the dominant renormalization is actually due to the top quark and that renormalization is negative. It's very sensitive to the mass of the top quark as we discuss in just a moment. In the standard model, that renormalization drives the quarkic coupling negative at some scale of capital lander, which you can see here is estimated to be somewhere around 10 to the 9, 10 to the 10 GB. And I show here a calculation by Degrassi et al. Now, when the Higgs self-coupling goes negative, it means that the brim of the Mexican hat turns down at large field values and there is a lower energy state and our present vacuum is unstable. Now that's within the standard model. My take on this is that we should look for physics that stabilizes the vacuum and one possibility is supersymmetry, although there are other possibilities for new physics beyond the standard model that could stabilize the vacuum. So this picture here illustrates the problems on the left. We have the profile of the Mexican hat and the top quark turns down the brim of the Mexican hat and you get this instability indicated by the red arrow and the red dot goes into a region where you've got a negative vacuum energy and where the universe stops its expansion and instead collapses into a big crunch. So here is a formula by Brutatzu et al. that describes this instability scale parametrically in terms of the Higgs mass, the top mass and the strong coupling constant. And if you put in the current determinations of those, you get an instability scale, as I said, around 10 to the nine or 10 to the 10 GB. So in the top right, the green ellipse indicates the world average values of M Higgs and then top. So M Higgs is by now well established. M top is still more uncertain and as you can see, that's the principal uncertainty as to whether we're really in the unstable region or the stable region. And since that world average was made, there have been additional determinations by the various electron collider experiments, although all of them, as you see, are outside the stability region. And here, just a good measure, I showed another calculation by Benekar Hotel, which also indicates that the Higgs mass and the top mass are in this unstable region. Okay, so we've got a precise Higgs mass. It's a puzzle for cosmology. What about its decays? So the Higgs decays should be proportional to their masses. And this picture here shows you the pattern of Higgs decays that you might expect as a function of the Higgs mass. Notice that the dominant production mechanism of the Higgs to gluons is a loop process and also the prominent Higgs into gamma-gamma decay is a loop process. So it's kind of ironic that the most prominent mechanisms, the couplings of the Higgs are quantum loop diagrams. Again, we're very lucky with a Higgs mass of 125 GB, there are many possible reduction in decay modes of the Higgs. Whereas, if just saying, it must be 750 GB, then we would have had a lot more problems. So this is what we expect for the decays of the Higgs. So I mentioned that the Higgs into gamma-gamma decay is very distinctive, but it's also very rare, 0.2%, and the decay in the ZZ star into four leptons is also rather rare. But the dominant Higgs decay mode should be Higgs into BB bar, that this is still not being discovered at the five-sigma level. So what do we know? So this plot shows you a compilation of Atlas and CMS data from round one, organized from top to bottom, according to the Higgs production mechanism and the Higgs decay mode, so gamma-gamma, ZZ, WW and TAL-TAL. So there'd be not some measurements, but as I said, still Higgs into BB bar has not been discovered at the five-sigma level. Higgs into mu-mu is something we'd like to see, the second generation mechanism. TT bar production, that's maybe now emerging, although still only at the four-sigma level. And for the future, we would like to see Higgs production in association with a simple top. So, three years ago with my then student, Tivon Yu, we said, look, if Higgs coupling should scale proportional to mass, what are the data telling you? So we did a fit where the couplings were taken to be proportional to mass, to the power one plus epsilon, and we fitted epsilon. And as you can see here, the value of epsilon is very close to zero. So the red line is the standard model of addiction, the dashed line is the best fit, everything is consistent with this particle being a Higgs boson. And for that reason, in our paper, we wrote that this particle walks and quacks like a Higgs. Now subsequent to our analysis, a much more precise analysis has been done by the Atlas and CMS collaborations, but again, you see the same thing, the data are completely consistent with the standard model expectation. So, do we have any reason to expect those physics beyond the standard model to be discovered tomorrow? And I would base my answer on this movie poster from James Bond with a couple of small modifications. And I paraphrase the title of the movie. Standard model is not enough. And in honor of James Bond, I give you 007 reasons for thinking there must be physics beyond the standard model. So 001 is this instability of empty space that I just discussed. 002 is dark matter, which I will turn to later on. 003 is the origin of matter itself in the universe. I won't say so very much about that in this talk. There's also a problem of neutrinos and their masses. There's a problem of the hierarchy of mass scales in physics. Why is the universe so big and old? We think that's because of cosmological inflation, which again, I would say, cannot be explained within the standard model. And of course, we want a quantum theory of gravity. So I could go on, but I think that these 007 reasons already indicate there has to be physics beyond the standard model. And many of these issues are being addressed by LHC run two. LHC run two. For example, a better measurement of the top fork may give us more insight into the stability of the vacuum. LHC experiments will look for dark matter. They will look for particles that may mitigate the hierarchy problem and so on. Now, I make no secret of the fact that my favorite extension of the standard model is supersymmetry, and I will spend some time later on discussing what are the remaining prospects for discovering supersymmetry. So let me first of all discuss this issue of the hierarchy of mass scales in physics. So this is a slide that I stole from Nathaniel Craig where he discusses many different attitudes towards the hierarchy problem. Some people will say there's no problem. Some people say, well, we just have to choose the parameters motivated by anthropic reasoning. I don't like those approaches, and I prefer to think that there is some new physics. And I'll discuss a couple of those in a moment. Now, I should say that there are many ideas for new physics, and I compare them to this World War I cartoon where there are these beyond the standard model theorists being bombarded by data that did not show evidence for their theory. And one of them is saying to the other, if you know of a better whole, go to it. And that's exactly what I feel about supersymmetry. Okay, supersymmetry is being attacked by experiment but I still think it's better than the other holy theorists. Okay, so let's talk a little bit about the hierarchy problem. So as you know, there's two different attitudes towards the Higgs, either it's elementary or maybe it's composite. If it's elementary, then when you calculate nuke diagrams, you get quadratic divergences, and the favorite approach is to cut them off to the scale of the order one TV with supersymmetry. So that's the left hypothesis. And then there's what I call the old right hypothesis, which is that instead, the Higgs is made up out of a further than 90 for non pairs, just like the pattern in QCD. Maybe those are bound together by some, many of the older ideas about that are not so successful, but one idea which is very popular at the moment is that the Higgs is a pseudo downbrew glowstone boson of some new broken strong interactions. So a convenient way for discussing this hypothesis is a phenomenological framework where you write down the same interactions that you would have of the Higgs in the standard model, but you allow basically arbitrary coefficients which I've highlighted here in red. So the Higgs boson couplings A and B, Higgs thermion couplings C and so on. And these couplings will be equal to one in the standard model, but maybe they're not one, maybe they differ. So experimentalists have analyzed this, for some reason, best known to themselves that make things more complicated by not talking about A, B and C, but by talking about parameters kappa. So this is a plot taken from a paper by the Geofedder collaboration. So in orange, we have the Higgs measurements, which tell you that the Higgs coupling to vectors and to fermions is sort of compatible with unity. What's interesting is to combine those data with a precision electroweak data, shown here in blue, and then you see you get a much tighter constraint on the couplings of the Higgs. To vector bosons and fermions. So this is another analysis, which was done by Atlas and CMS. And what I do here is overlay the predictions of some representative composite Higgs models. So these minimal composite Higgs models have a parameter zeta. And as you can see, this parameter has to be close to zero if you want to be compatible with data. Anyway, the moment you cannot rule out the composite hypothesis, but there's no evidence in favor of it. So an alternative approach is to say, well, maybe the Higgs has the same couplings as in the standard model on slide two of my talk, but in addition, there are higher dimensional couplings, for example, couplings of dimension six. So if you write down all the dimension six couplings compatible with the symmetries of the standard model, you get thousands of them, literally thousands of them. On the other hand, if you are interested in testing just a subset of the data, precision electroweak Higgs data and two more gauge couplings, you can simplify matters, you can ignore all the complications of flavor and focus on a relatively limited set of couplings. So that's what we did in this plot that I showed you here on the right. So I'm afraid I don't have time to go through the definitions of these dimension six operators. Anyway, this particular set of six operators is constrained by Higgs production, shown in blue, by LHC triple gauge couplings, shown in red. Black is the global combination, and the black is if you allow all the operators to be switched on simultaneously. If you just switch them on one at a time, you get the green error bars, which of course are much more precise. I'd like to emphasize again that the Higgs couplings should not be considered in isolation. There are also important constraints coming from triple gauge couplings, which are illustrated here. So this paper, I've got Varkovsky et al, illustrated that the triple gauge couplings shown in orange, and the Higgs couplings shown in green are largely complementary, and you put them together and you get the blue constraints, which are much more precise. So here's another slide that I stole from Nathaniel Craig. And I will advertise the fact that I'm a fan of supersymmetry. But one of the problems is that there are many different supersymmetric scenarios, compressed spectrum, r-parity violation, minimal models, not so minimal models, natural models, unnatural models, et cetera. So one of the complications, as I like to say, is that there are no signposts in superspace, and we have to look at many different models. Now, perhaps I should have already emphasized that I like supersymmetry, as you know, and here I've written it in the largest font that will fit on the slide. And I would argue that LHC11 has actually given us three additional reasons for loving Susie. One is that it stabilizes the electroweak vacuum, the issue that I discussed at the beginning of the talk. Susie also makes a successful prediction for the Higgs mass, it should be less than 130 GB. It also predicted correctly that the couplings should be within a few percent of the standard model values as we saw earlier in the talk. And of course, these reasons for loving supersymmetry should be added to all the previous ones, like the naturalness of a hierarchy that I mentioned, grand unification, string theory, and dark matter, which I will turn to in a moment. So this slide I can probably skip over, I'm going to be working within the minimal supersymmetric extension of the standard model, certainly, MSSM. So of course, the experiments have been looking very hard at evidence of supersymmetry and no supersymmetry yet. They've also been looking for other, more exotic physics, and they haven't found anything of that either. They haven't found black holes, they haven't found any of these other hypothesized new physics. So I think that everyone is a bit puzzled at the moment how to continue the search for new physics at the LEC. Should we just continue with the same models as previously? Should we be thinking about new models? Should we be thinking about unexplored corners of, for example, supersymmetric parameter space? Should we be thinking about novel signatures that perhaps have not been started fully? So I'm engaged in an effort together with a group of theorists and experimentists called MasterCode to analyze the constraints on different supersymmetric models incorporating all the available data. So we incorporate the data coming from precision electric observables. Actually, many more observables are shown here. We also incorporate many flavor observables coming from BDK, also from KDK. We incorporate the constraints from dark matter. So there is the overall density of dark matter and there is also constraints on the spin independent and spin-dependent scattering of dark matter on regular matter. And of course, the energy of the observables. So in all this, are there any hints for new physics? But of course, there's been this long-standing puzzle about the anomalous magnetic moment of the mule. And as you can see here, the current discrepancy between the Brookhaven measurement and the best theoretical estimate in the standard model is about three and a half standard deviations. Maybe not conclusive. The good news is that soon, Fermilab will do a repeat experiment. Another area where there seem to be significant anomalies is B into strange cork plus dileptons. And I'll say a little bit about that later on, but not very much. I think it's very difficult to explain in at least the sort of supersymmetric scenarios that I've been studying. So here I show you a typical spectrum from a global fit that we are about to release in the phenomenological MSN or PMSSN. And so what you see here is the MSSN spectrum. And the point I would like to emphasize is that in this model, at the best fit point, a lot of supersymmetric particles are accessible to future bounds of the LAHC. So you see here that many of the corks are accessible to the LAHC. Sleptons may be more difficult. Maybe one could also look for some of the electric enos. Now what we also find in this model is that there are a couple of other possible LAHC signatures which are worth exploring. So these spiky lines that you see here for various fits to LAHC 13 data, the dash lines into LAHC 8 fits with G-2 solid lines and sorry, the blue lines and without G-2 green lines. Now, an interesting thing here is that, well, if you believe in G-2, it turns out that the next lightest supersymmetric particle probably has a short lifetime, less than 10 to the minus 10 seconds. But if you're not sure about G-2 and you look at the green lines, you'll see that the next lightest supersymmetric particle lifetime could be as long as 10 to the plus three seconds at the 95% confidence level. I should be cut off at 10 to the plus three seconds because a longer lifetime would give you problems with big bang-mute synthesis. So a long-lived sparticle is a potential signature in this model. Another interesting thing to look at is Vs goes to mu plus mu minus decay. Now, this plot is maybe not tremendously clear. Now, what you can see is that there is a preference for a value of this decay close to the standard model, but the decay could be significantly smaller. And in some of these fits, the best fit value is something like 0.8 of the branching ratio of the standard model. And I remind you that the best fit to the card experimental data is actually below the standard model value. So this is maybe something worth watching. Now, as I said, there's been a lot of excitement recently about possible anomalies in B goes to K in K star mu plus mu minus decay. And these are a couple of plots taken from one analysis in terms of the coefficients of operators 09 and 010 with muons and with electrons. So the data indicate that there might be a contribution beyond the standard model C9 for muons. C9 as you would see has a vector like coupling to muons. Other couplings cannot be excluded, but that's a thing that seems to be most indicated. Now, I personally prefer to take a sort of weight in C point of view. I think it's very difficult to explain this with supersymmetry, but many phenomenological models involving additional Z-primes and electric quarks which might be able to explain this. But now we turn to the search for dark matter. So, as you know, there'd be many experiments looking for spin independent dark matter scattering. And the existing limits are shown here with solid lines and prospective future limits are shown by dashed and dotted lines. Actually, this is a bit out of date because as you'll see in a moment, there've been some more upper limits on spin independent dark matter scattering since this compilation was made. So here, I know also in yellow at the bottom the neutrino floor, this is a background coming from from astrophysical neutrinos. And in pink here, you have what? At least allowable this considered to be the possible range of predictions in supersymmetric models. So here I show our predictions in this phenomenological MSSN which I mentioned a moment ago. So here you see some of the more recent limits from LAPS, Xenome, Lantan and Panda X. As you see, according to our analysis, the dark matter scattering rate in the phenomenological MSSN could be close to the current limit, but it might also be below the neutrino floor. Now, in addition to searching for spin independent dark matter scattering, there are also experiments looking to spin dependent dark matter scattering. Current best limit, direct limit comes from the PyCo experiment. And here we compare the predictions of our phenomenological MSSN study with the PyCo limit and you see that again, it could be quite close. Okay, so I've talked about dark matter experiments. I've talked about past LHC results. Here is the prospectus for future runs of the LHC. So now we're coming towards the end of 2017. The LHC has been running extremely well. It's accumulated something like 40 inverse factor bands this year to add to the 35 or so that it had previously. It will run again next year and then there will be a shutdown. Following that shutdown, it's hoped to push the integrated luminosity up to about 300 inverse factor bands so about 10 times more than we've analyzed so far. And then there will be a further upgrade to the high luminosity LHC about 10 years from now which eventually should take the integrated luminosity to about 3000 inverse factor bands. So almost a factor of a hundred more what have been analyzed so far. But this is to say that there's still good prospects for discovering new physics in that hundred times more data. However, obviously people are thinking about what might be a possible futures collider beyond the LHC and one of the ideas that's being discussed both at CERN and in China is the idea of a future circular collider. So here the idea is to go to something like a hundred TV in the center of mass in proton-proton collisions and to have very high luminosity in plus and minus collisions of course on low energies. And that gives you a combination of exploring the 10 TV scale directly in proton-proton and indirectly to precision measurements in E plus and minus. So that's a vision which is shared by both CERN and China. The picture here shows you how such a large hundred kilometers circumference collider might be located near CERN and going around Geneva. Now when one talks of E plus and minus colliders of course there's different options on the table which illustrated in this slide here. So in red we have a large circular collider option which I just discussed and I highlight in this ellipse the fact that it can give you extremely high luminosity at low energies which will enable you to have unparalleled, accurate measurements of the Higgs and also electro-weak measurements. Another possibility for the future is to build a linear E plus and minus collider and the highest energy proposal is the one outlined here in green click which would run parallel to the shore of Lake Geneva close to CERN. Now these can be compared with the ILC highlighted here in blue. So the ILC doesn't go to such high energies doesn't have such high luminosities but maybe it's a proposal that is more ready for approval and so we'll see what happens with that. I just wanted to show one plot which illustrates the precision possible with a future circular E plus and minus collider. So I showed you previously this epsilon plot. So here is a possible future epsilon plot and you can see that the uncertainty in the mass dependence of the Higgs cupping is down at the per mill level. Of course that's a machine not just to Higgs physics it would also produce something like 10 to the 12 Zs 10 to the 8 Ws, millions of tops and so on. So this 100 kilometer tunnel what I was talking about could house either an E plus and minus machine or a Hadron Hadron machine. And of course the Hadron Hadron machine would also produce lots of Higgs bosons and these are the dominant production mechanisms all the way up to 100 TV. And here what's particularly interesting is the possibility of measuring double Higgs production which will be sensitive for the first time to the what, perhaps not for the first time will be the most sensitive way to measure the triple Higgs cupping. And of course with such a 100 TV machine one could also look for heavy new physics such as heavy squarks and purinos and this plot shows you that the reach for squarks and purinos extends above 10 TV. Okay so that brings me to the end of what while I was prepared. So the discovery of the Higgs boson has been a great victory for both theory and experiment but it's also a big challenge of theoretical physics particularly in the future. Now is the Higgs boson really as simple as it seems? To many of us that seems inconceivable but we don't know which direction to go beyond the standard model. So as I said maybe the LHC will discover new physics and it will accumulate something like a hundred times more events that want to be analyzed so far. If the LHC does discover new physics then surely the priority for the next accelerator will be to study it in detail. Of course if the LHC does not discover new physics then we should focus on measurements of the Higgs boson. In either case in my opinion the large circular collider may offer the best prospects for particle physics tomorrow or the day after tomorrow. Thank you. Okay thank you very much John. Let me just go back to the webcam version. Okay so thank you very much. John was super interesting your talk and I guess we can start with the session round but before just to let the people that is following the streaming or watching this video in YouTube in the future that you can make comments or questions right here in the comment or in the YouTube chat and so now we can start with some question for the people that is present here in the Hangout. So if anybody has a question please unmute yourself and ask it directly to John. So yeah. I have a question. Please. Can you hear me? Okay. Okay thank you very much. It was very nice talk. Regarding this very last point if the LHC detect nothing, not new physics what the main reason to study in deeper the Higgs boson would be to find new physics or what would be the main reason to focus on the Higgs boson? Why not I don't know focus on look for that matter or other things. Okay so what I was assuming in that line there was that the LHC does not find any new physics so in particular it doesn't find dark matter. Now of course there are non accelerated experiments for dark matter and those should certainly they will certainly continue but I think the LHC does not discover dark matter. It's difficult for me to imagine that a for example a low energy in plus or minus collider would discover it. High energy plus or minus collider maybe a large circular collider perhaps a much bigger chance. But the one thing that one can say is that the Higgs is certainly there. And so this should probably form the core of any program for new physics after the LHC. If the LHC doesn't discover any other new physics. Okay thank you. So is there any other question for John? So for the moment I have some questions. When you were talking about circular collider or linear collider beyond the scope of these searches is to go like is it possible to do precision physics with this type of accelerators with the one that has a lot of luminosity at low energy? Or is more just to try to find new particle by increasing the statistics? So if you can see my screen, you will see that the cross section for example for Higgs production but I could show you similar cross sections for other particles. The cross sections for Higgs production go up by almost two orders of magnitude from the LHC to a hundred TV machine. And the hundred TV machine, the design would be to get a larger luminosity. So we're gonna get at least towards the magnitude more Higgs. So I think then the challenge would be come on and do precision calculations and precision measurements. And probably that's gonna be possible and we're talking decades away from now. And I think that in between now and then experimentalists will learn how to do a more precise job and I think also we theorists will have time to do a more precise job. So yes, I think with the LHC, so with the F such a circular collider you could in principle also do precision Higgs physics although it's gonna be tough. Yeah, but what about the quartic coupling within the Higgs? Because I heard that this type of coupling is kind of a nice starting to see if there is more a larger number of Higgs's or if it's the Higgs of the MSSM or it's a Higgs standard model or something like that. So that's why I highlight on this slide. You can still see the slide mate. Yeah, yeah, yeah. Yeah. So that's why I highlight the process of double Higgs production. So the double Higgs production actually gives you sensitive to the tri-linear coupling. Now the tri-linear Higgs coupling is precisely predicted in the standard model. And as you say, any deviation from the standard model value would be indicative of new physics, maybe double Higgs, maybe supersymmetry or something like that. So there've been many discussions of how accurately you could measure the triple Higgs coupling with some other accelerator. LHC I think prospects are very, very weak. A low energy linear collider, maybe you could get some sensitivities through radiative corrections. Click, I think you would have a better chance because you've got three TV in the center of mass. Well, I don't have the numbers to hand. I think what is clear is that a hundred TV proton protocol collider would give you a more accurate measurement than any other. I might mention that people have also considered measuring the quartic coupling. So here you're sensitive to the triple coupling. You've also considered sensitivity to the quartic coupling. And maybe that's possible, but I think that's going to be very tough. Yeah, it's much suppressed than the tri-linear. And there's also a problem of the the experimental signature is not very distinctive. Yeah. Thank you. Is there anybody with more questions? Please unmute yourself and ask Ed. Yes, just to see if I understand correctly, John, did you just say that even in the future circular collider, the prospect for measuring the quartic coupling is super hard? That's my impression. So there have been a couple of papers on this. Maybe people would like to explore it in more detail. I remember in particular it was a paper by Kazuki Sakurai and somebody a couple of years ago that was one of the first papers on that subject, that I saw. So if you're interested in pursuing that, I recommend looking for papers that Kazuki Sakurai has written, if it was without me, and see whether there's something interesting there to follow up. Okay, okay, thanks. Yeah, I guess Koel has a question. I don't know. Yes, thank you. So one of the things that the MSSM doesn't address is neutrino masses, right? So I guess that most people expect that you just embed a high-scale CISO into the model and just deal with it, right? But I was wondering if you chose another model that could have some impacts on the low-scale phenomenon. What kind of impacts would those be? What would we have? Right, well actually I think that even if you just glue together the CISO model and the MSSM, there are potentially interesting flavor-changing signatures. But these would involve sparticle loops. And if the sparticles were relatively light, obviously those effects would be larger than if they were relatively heavy. So this is not something that I've looked at recently with the latest experimental limits on sparticle masses. But I think this is something which is worth keeping in mind. I mean, I'm thinking of processes like new goes to e-gamma, new goes to 3e, anomalous, new e-conversion. And actually there are experiments, ongoing experiments and proposals to address several of these. But I think that's an interesting line to pursue. Sure, sure. I was actually wondering about collider phenomenology. Sorry, it wasn't... Ah, collider, not much. Well, again, this is something that I thought about in the past. So you might get flavor-changing sparticle decays that you could look for what a collider, but let's first of all find a sparticle. Of course, there are ideas for how you could test various different variants and seesaw models collider without a vocation super symmetry. And I don't have anything useful to say about them, but they're also worth pursuing. Good, thank you. Okay, anybody has another question for John? Yes, hello. Can you hear me? Yes. Hi. Yes, regarding the G-mu-2, if in the next few years Fermilab confirms like the discrepancy between the standard model and the prediction and the, yes, so or the measurement and the prediction from the standard model, what would that imply for the collider physics? I mean, would we, if Susie's there, would be guaranteed that we find something in the next 20 years at the DMT or could it still be hiding? Okay, so I showed you some results from FITS where we take seriously the discrepancy in G-2 and FITS where we discarded the discrepancy. And this paper that we're just preparing will contain a lot more discussion of that. I think it would be very interesting indeed if Fermilab confirms the previous experimental measurement. Then I think Jonas would really be on our theorists to try to do a better calculation of what's been done so far within the standard model. And there are efforts in that direction, for example, the Lattice people see to be making progress towards calculation of light by light scattering and also towards a theoretical, as opposed to experimental determination of the head drawn vacuum polarization contribution. So that's a scenario that I like where you have a continuing discrepancy between the experimental measurement and the theoretical calculation and that will give us lots of things to try to understand. But if the discrepancy goes away, then I think all that tells you is a symmetric path or presumably relatively heavy. Yeah, I don't know what's happened with Teddy Griffey, I don't know how to answer. Oh no, thank you, thank you, yes, that's fine, yes. Okay, okay, so John, I have one question before to continue the round of questions from the people that is in Hangout, that is from YouTube. DC Adam is asking a kind of general question. How would you explore the new physics of extra dimension at CERN? Did you have some words about extra dimensions? Yeah, so people have considered various different experimental signatures. So in some, there's many different types of active dimensional scenarios. So in some sense, the most conservative scenario actually looks a bit like supersymmetry, but with a more compressed spectrum. And in that case, you would have potentially a dark matter particle, which would be the lightest colloquial particle. And that would carry missing energy, but not as much as in supersymmetry. And that scenario maybe should be revisited because we now know that if there is a missing energy signature at the LAC, it's very small. Well, small as in simple supersymmetric models. There's all sorts of other scenarios, right? I mean, there's a famous black hole scenario where gravity becomes strong in extra dimensions and you would use microscopic black holes at the LAC. This is something that people are still looking for. And I think one can expect more stringent results coming from running at 13 TV. And I think those searches are interesting because they're also sensitive to other scenarios for new physics that produce very complicated events with lots of, perhaps, relatively soft particles. And one of these that I've studied, in fact together with Kazuki Sakurai, is transitions, Bayon number, the alien transitions mediated by Svalovans. And this is something that was discussed in the 1990s and then people got discouraged by it. But then in the last two or three years, Henry Tai has revived the possibility of Svaloan transitions. And in fact, just in the last few days, he's had a new paper out where he argues that there could be Svaloan transitions that would be observable at the LAC. But to come back to extra dimensions, I think there's many different scenarios. And yes, the experiments are still looking for them. I just mentioned a couple. Okay, thank you. Just I wanna continue on another question that was related with the question that was before, well Federico, that in one of the plot that you show about with this master code, most of the constraint from dark matter in the case of supersymmetry, it suggests that the dark matter has to be heavier than 100 GB. But then it's like from the spin-dependent cross-section, you have a very, like a cliff in the, I mean, you can go to very, very, very low spin-dependent and spin-dependent cross-section, yeah, these plots. So the only prediction that can be done with direct detection experiment in the context of supersymmetry is just to say that the dark matter is heavier than 100 GB. It's not possible to go to lower masses, for instance. So I think that in the phenomenological MSSN, yeah, definitely. It's difficult to go much below 100 GB. You go a little bit below. Now I didn't perhaps explain all the colors in this, in these plots, I didn't have enough time, I apologize. So the green contour that you see, which goes down to the lowest masses for the dark matter particle, this is actually a three-sigma contour. And the blue is two-sigma and the red is one-sigma. So if you believe in one-sigma, then the lower limit is significantly above 100 GB. If you believe in three-sigma, it could be less than 100 GB. It also happens that the two-sigma contour is about 100 GB. So in that sense, other type of dark matter claims, like at lower masses, it are impossible for this case, for the phenomenological MSSN, like if somebody is still believing in Dhamma signature or something like that, it would be impossible in this sense. So there's a well-known tension or conflict between the results of Dhamma and other experiments, such as the experiments Crest and CDMS that I showed in the left slide. And in fact, there are other experiments as recently, for example, the Chinese experiment CDEX, which has also got an interesting limit in the low mass region. So I think it's very difficult to reconcile Dhamma with conventional with dark matter scenarios. I don't know how to do it. That's good. So is there is more question from the people here in the hangout, please? Yes, yes, one question. Just to be sure, with the current precision, it is possible to affirm now that the instability of the his potential or we need to wait for more data in the future. I'm sorry, I didn't understand that question very well. Roberto, did... Yeah, yeah, it was... The instability of the his potential, it is compared now that the potential, the his potential is metastable at ISA with the current precision data. So you're talking about the behavior of the Higgs potential according to the current data? Yes, if it is confirmed that it's metastable or there is still a room to... So I wouldn't say that it's confirmed. I don't know whether I can quickly flash back and find the appropriate slide. As I mentioned, the biggest uncertainty is in the mass of the top hook. And there are important hadronic QCD uncertainties in that. And of course, people have tried to estimate those and that's included in these error bars that I show here. There are people who still question those hadronic uncertainties and I would hope that with future LHC analysis, it would be possible to reduce those experimental side of those QCD uncertainties. There still is a theoretical issue in terms of relating the parameter in the Lagrangian to the pole mass of the top quark. But that I think is understood at the level of probably something like 250 MeV. So that would be a small amount of uncertainty and the size of these ellipses. But anyway, I think we should not reach any definite conclusion. I don't think we can reach any definite conclusion at least until we've seen the one-two data. Thank you. So any other question? Because here in YouTube, I don't get any other. So maybe it is okay for this webinar, I guess. John, you have talked a lot and maybe you are a little bit tired with all the stress that we suffer with the technical issues with the transmission. Well, anyway, thank you for, as I said, the invitation and thank you for helping with the technical issues and I apologize for the delay. But I hope, anyway, it was good to meet with you even if I could actually see you. And so I wish you good luck in the future of the webinar. Yeah, I mean, we are working on that to make it each time with not any problem. But yeah, first of all, I want to thank you for being here and to agree to give this webinar. And this special webinar because it was the number 50 of, so we already have webinars from the beginning of 2015 when we started. And for the people that are now watching the video, just if you like this idea of the webinars about research, topic, and physics, you can subscribe to the YouTube channel and then you're going to get all the notification when we do and you can see all the previous webinars that we have done. So for all the people that are viewing us, so we have to celebrate. And if the rest of the coordinators that are here in the Hangout session, sorry, John, that you cannot see us because the webinar is not, you can't see us. But I have here a champagne that I'm going to just make a small toast for this special location. You can see here. I'm just... I don't make a mess here in the room, in my house. So I'm going to try to open... This is because it's a special location, because it's the 50 and we have done a lot of effort with this webinar. So let's see if we're going to... I don't destroy my computer. You're going to say... So while you're doing that, I'm going to try to get up on the screen another bottle of champagne. You're sure? Yeah, okay. Three, two, one. It doesn't go. It's not working. Technical problems. Honestly. And explode, of course. Okay, so... When you see my screen? Once I can just jump, because I have my hands wet now, just to show to the people that I have my... I can show it. Champagne, I can show the screen. Now, once... Oh, I can see it, wait. Let me just... Now I have a mess here with the... Okay. The entire screen. Okay. Wow, we can see your... That is the champagne for? Okay. So the night before the Higgs discovery was announced, my wife and I had Peter Higgs to dinner and in our house and we opened a bottle of champagne. And of course, then the discovery was announced and everybody was very happy and then the Science Museum in London asked me to donate our empty bottle of champagne to their collection. So then they censored on the traveling exhibition around the world and actually here it is in Singapore and you could make out a lady in the background that is actually our daughter who happened to be in Singapore and you called the exhibition and took this photo. So anyway, here's the Higgs champagne. And it has the potential in the bottom I guess, no? Absolutely. So one question just beside the talk. The photo of the desert, that is let me guess, is it... It's not the Takama Desert, no? No, it's not Takama. In Colombia or in Peru, maybe? No, no, it's actually in Argentina. It's a little bit south of Balagüe where the Auger experiment is located. So it's on the edge of Patagonia. Yeah, because it looked like for me it was familiar kind of. But most of the desert could look similar. Yeah. But the prints in the soil, are actually proof prints. And that's a good clue that it must be in Argentina because those are gaucho proof prints. Yeah, that's nice. Yeah. I left a mess here with the champagne. I'm cleaning the... Again, for all the people that is following the webinar, for you John, we are participating. And I guess we can lead the transmission till here. Just a very small announcement because with the law of physics next 31st of October we are going to do a Dark Matter Day. We are going to participate in this event of Dark Matter Day. And we are going to use all the what we know with the law of physics. So we are going to be connected with three different institutions in Latin America Contefici Universidad Católica de Chile and the Universidad Antioquia. We are going to be connected and talking about Dark Matter with different scientists that are working in Latin America. So, John, thank you very much. All the viewers, thank you for watching. Thank you. And see you next time. Okay, bye.