SMU Physics Department Speaker Series - Prof. Pierre Ramond (University of Florida)

[Music] okay so welcome back everybody to the smu physics department speaker series for spring 2021 and this is the final event of our academic year which is dubbed the spring colloquium and in a moment i'm going to invite professor dirdhana balaki shieva to introduce today's distinguished speaker professor pierre ramon but before we get started i wanted to make some of the usual reminders here so to our audience on zoom i just wanted to remind you that to ask a question during or after the talk you just need to type the word speak in the chat window we use that as a kind of speaker cue and we'll get to you in the order in which those those requests to speak arise uh if you ask to speak uh during the presentation we'll interrupt professor ramon at the next slide change boundary or thereabouts okay um and you'll only be able to speak when called upon by a moderator which i will serve as the moderator so donna doesn't have to worry about that for the event um the other thing to know is this event is being recorded on zoom and it's being simultaneously live streamed on youtube the youtube live stream is non-interactive but we have a number of participants on the live stream today so to our about half dozen participants on youtube today welcome without further ado i'm going to now hand things over to professor durdanova akushieva to introduce today's distinguished speaker dardana thank you very much it's my honor to introduce dr pierroman is a distinguished professor of physics at the university of florida and the director of the institute for fundamental theory at university of florida he earned his phd from my alma mater syracuse university and has held a number of notable positions including as a postdoctoral fellow at fermilab he used to call be called national accelerator laboratory and a militant senior fellow at caltech a member of institute of advanced study at princeton university distinguished simon's fellow at kavli institute for theoretical physics he is extremely well known for initiating super string theory generalizing paul direct's work on point-like particles into a context of string theory and he led to the discovery of the two-dimensional supersymmetry and the set of stage of fully uh four-dimensional supersymmetric formulation he is the single author of three physics textbooks i have them all uh on quantum field theory physics beyond the standard model the group theory his research research has won numerous prizes um too many to you know mention old but uh mostly uh oscar clown metal light my third prize uh danny heimann prize and most recently in 2010 direct model a direct medal that was issued at icdp also one of the schools i went to we are honored to host him um our dearest professor ramon today to speak on unfinished standard model and i underline unfinished standard model okay very good well thank you thank you very much now i have now this distinguished professor has to learn how to share his slides the unfinished standard model yes okay now so so what the the the talk basically as i said was pandemically inspired because it led me to i don't know to some some you start to lend some historical perspective uh and then talk about the standard model talk about possible completions and in particular uh work in detail on the neutrino strategy for trying to understand more about the standard model which is the type of work i'm interested in but i it will basically tell you more or less oops something okay all right okay so this is what so now i we we are as i said earlier into physics which still lives in a shadow of a genius and uh and then mark twain is said to have said he's supposed to have said this thing history does not repeat itself but it sure rhymes uh and uh so maybe it was it's not such a bad idea to go back in a little bit in time and see what what um how well how phil got to be where he is so in a newton century um the uh one once people understood what newton had done their application to newton's laws led them to understand a whole host of phenomena no matter what they did they applying newton's laws just worked then historically towards the end of that century electromagnetism came up namely with the invention of the voltaic cell that you could store it and you did not have to take your life in your hands to study it and uh that led to new physics in the new physics of course is embodied by maxwell's equation etc then a century later oops oh okay so okay so now let's look about i don't know i'm sorry look an einstein century well last time century of course there's quantum mechanics there's general relativity but for us particle physicists there is the standard model and then we are left here with something we have no idea what it is namely what am i doing you know dark matter does dark matter you know does it what place does it have we have no idea all we know so far is that we we have things we do not understand we don't understand quantum mechanics we know how to use it we we don't understand general relativity we know how to use it we think we understand the standard model we have dark matter we don't know what it is so it's a time full of full of questions the question the only question is can any of these questions be answered within one's lifetime okay so the one thing that is very important is the ubiquity of the vacuum the in a in in a century well before when newton was was bought a child descartes view of the vacuum was a bunch of vortices the cart was the big genius of the time okay but the vacuum then under newton basically was full of nothing there was okay and then with einstein we know that it's full of quantum okay all right but now i would like to make a pitch for history repeating itself which is the brownian motion calculation the brand in motion calculation of einstein and smallskey okay basically uh linked a physical phenomenon namely brownian motion to uh a fundamental insight using statistical mechanics basically okay but the thing that happened that was wonderful avogadro's number came out okay and avogadro's number was just the purview of chemistry and once this happened the whole that was again a real game changer because all the people who were doubting the kinetic theory and every and everything which were many of them suddenly understood that this this was the real thing okay and that is where i say that perhaps uh we have similar problems right now facing us first problem we have a standard model vacuum now the standard model vacuum we know that in order to make a standard model work we have to get there's there's an order parameter in it and the uh there's something and out with the soil parameter comes up the higgs part comes the higgs particle which is extremely light compared to what its quantum expectations are and the question is is that just a uh the effect of the theory of the namely we could add more like we would add super symmetry we could do all kinds of addenda to the theory or maybe does it tell us that there is something wrong with our view of space-time in terms of in terms of the vacuum that's an open question and then of course it is not too long ago cosmological constant which was obviously zero by from the theoretical standpoint right is there and i think it's it's fantastic because the fact that it is there we don't understand we first of all we're not totally sure whether or not it's called it's a cosmological constant but it looks like it its equation of state looks a lot like it and i go back to this to to mark twain why because when the next genius when when when she solves the cosmological constant she gets the number of of the cosmological constant the physical number in terms of of the cookie theory of space-time we will know that that cookie theory of space-time will actually be probably has to be taken very seriously so there's something wrong with our vision of the vacuum we don't really know it we sometimes it works sometimes it doesn't but somehow the the standard mod the higgs the lightness of the eggs is really a problem that nobody understands and my my field has gone to a stand still as a result of this okay all right so let me tell you in what ways the the tell you a few details about the standard model okay so you know it's a theory of strong weak electromagnetic force between carol leptons and quarks but it is a it's a beautiful quantum field theory but it is built on flat space time which is something we don't really know it's a you think of the flat space time basically as a phenomenology phenomenological description okay but built on that it's like building a fantastic building on the swamp you know okay and sometimes something doesn't work out so we don't understand at all what what flat space time is in fact we don't understand what space space is now when i was a child the standard model the the the thing for a quantum field theory was that it had to be renormalizable and the renormalizability of a field theory meant that it yes it blew up at infinity and in very short distances but if you put a cut off and the cutoff was so far away from the experiment that you didn't really matter so if you have a logarithmic cut off and i was thought that basically quantum electrodynamics was good because it was normalizable although people like dirac thought that it was the wrong theory okay and and nowadays the view of this this model is exactly the the direct view it's an effective theory it's just an effective theory okay with a neutral scalar particle which happens to be much lighter than the code of energy that's the thing we don't understand okay and the explanation of such a small mass awaits and the question again is is there super super symmetry would actually alleviate the problem somewhat but uh could we does it really necessitate a rethinking of what space time is and that is that is i say way way beyond my my pay scale but when when in the middle of the pandemic i start thinking about stuff big big stuff like this those are the kind of questions that come up however from the point of view of working on things it works very well i mean you can for most things you can disregard these things okay well let's see so now let's talk about the local symmetries my local symmetries of the standard model is you three crosses so 2 cross u1 there are global symmetries they could be which is variable number minus lepton number there is a there could be a peachy queen symmetry we don't know okay my i say that because my my colleague that's here at um in florida is pierci kivi who whose life depends on me on the axiom and it has basically three chiral families which survives 50 years of experimental tests okay and the model has such broad shoulder that it accommodates but does not explain neutrino masses in other words you put an addendum okay and you can explain but the important thing about the standard model it does not challenge established principles okay there is no direct challenges to the basic laws as we know them so that makes it very difficult because usually fundamental progress comes up when there is a paradox between between something that works and something that that the fact that it works implies that some cherished principle has to be dropped something has to be done and that happens of course rarely and i but i think this is only for the true genius you know who basically understand what it is now let's look at standard model and general relativity now the good news is that the from the standard model's point of view you ask yourself where's the cutoff coming from because it's an effective theory with with the cut off deep in your valley well general relativity probably offers such a cut off so in a certain sense from the point of view of a particle physicist general relativity it just just gives it gives you a time where you know that perhaps space time will break down and and uh something funny is going to happen but there is something quite spectacular about the standard one which is not very much mentioned is that there's an absence of of gravitational camera anomaly the standard model has zero anomalies uh connected with with the chirality which is quite quite remarkable because it could have could have been different and and we don't understand so the the universe which is what the standard model explains somehow is shielded from these anomalies even including the gravitational anomaly and the most remarkable thing in order to cancel the chiral anomaly you require both carol leptons and quarks in other words they combine into this so this is really the first time that that leptons and quarks are unified in their inner ability to car to to basically get rid of a car analogy that means that the standard model is a shadow of something very deep except we don't know what it is now what about dark matter well the sad thing about it right now is that the standard model there's not nothing in the standard wall that requires dark matter for consistency so dark matter could be there it could be an add-on but it doesn't challenge any principle okay all right but we do know that the standard model interacts with dark matter why because gravity uh certainly is susceptible to dark matter okay and through and then the standard model is susceptible to to go to gravity and therefore they're with their amplitudes and therefore at some level they will have to be interactions that's quantum mechanics coming in there is no choice except we don't know okay so we don't know yet what partic what dark matter is is it just a bunch of new particles like the axion or or some supersymmetric thing or is it a game changer is it something that truly changes you know uh wait we don't know that yet in other words some people there is it on the left-hand side of the right-hand side of einstein's equation so to speak now in comes a way now the gods the gods come in so the dirac principle of mathematical beauty the iraq talks about the binomial the bi-modal exploration of nature one experiment in observation and from the iraq's point of view mathematical reasoning and he talks about simplicity and beauty and and simplicity for him is newton's equation okay the beauty for him is the special relativity okay and i should i i should tell you something very interesting that and from this point of view you should always look for for beautiful things which of course is very weird for a physicist to say that but then dirac was certainly a weird physicist okay and the and one one of the things for example talking about a deep thought talking about this is that newton's equations are simple and the question that the iraq asked himself if they're so simple why is the universe so complicated and and then he says well it must be quantum fluctuations okay this this this remind in 1938 so this is this is the kind of little remark that the gods leave behind and and and now of course it's it's well known people use this all the time but that was that was the the the complication came came from the boundary conditions basically which can vary it's kind of remarkable now i think that simplicity and beauty will will meet at the standard model cutoff that will be the point where everything will go unfortunately the standard model cutoff is is not within the reach of experiment and right now i don't think anybody is smart enough to understand what's going on and we need experiment okay now it's the cruel thing about the standard model is that it's weakly coupled at this at a certain scale if you look at 10 to the minus 15 g well if you look at 100 of the of the of the proton of the extent of the proton for example you find that basically all the couplings in the standard model are perturbative and this is very cruel this is a very cruel thing for theorists because perturbative theorists can use perturbation theory and they can use their normalization so they can use so it gives a field of play to theorist to extrapolate okay using the equations to shorter distances which is quite remarkable okay so you look at the intersection of gauging and newcomer couplings in ultraviolet you find that the in when you go in the ultraviolet there is a renormalization group equation which which tells you that the the the coupling of the higgs potential that makes it go up as a go up as a function of field configuration uh he decreases through the radiative corrections unlike the landau pole by the way which increases the the coupling and it can cause instability and there's some sort of a plant chimney that appears very very bizarre thing okay but this is one of the things that people look at so the bridge to show the distances there it is we know there's a bridge we know that theories can go there we are looking for patterns okay all right so the grand unification so one way of going through this bridge which people following the beautiful work of patti and salam okay was basically that there was a unification of the local symmetries through asymptotic freedom and that there was a convergence in your autoviolet of the various couplings and that led people to take to look at the symmetries of the standard model and extend to su 5 so 10 e6 and other groups okay which had the consequence of barrier number violation okay because in a pati salon way of looking at it a lepton the electron was the fourth flavor of quarks with that that symmetry was broken so there was in preserve burying a minus lepton number but basically lepton number was but proton decay hasn't been seen so that means that this introduces in those in those ways of doing things are cut off in the ultraviolet okay we could look at another way the intersection of the big quark and the tower left on mass going in in the outer valley the mass of the beak work okay case described as half the mass of the epsilon bb bar compound and threshold okay and experimentally the mass of the big quark is about three times the mass of the tau electron now if you use the but the b quark mass is renormalized by the strong by by qcd to an extent that is not met by the lepton and you can define a new scale where m b equals m tau because m b equals m tau is a special scale for doing for the su5 theory so the factor of three from the renormization group sets another ultraviolet scale okay which would mean that new particles would be required but then there's something because if you use su5 you get proton decay and i'll be much much too fast so again we don't know what we do now this is i want to make a simple pitch before i turn to the neutrino discovering proton decay well if we discover proton decay that's a direct bridge to planck scale physics so you don't have to increase the energy yeah use avogadro's number make a lots of like a hubble candle the present lifetime of the proton um which is in the e plus by naught channel is 10 to the 35 years that super cameo conde has now the near future next 10 years say it will be increased to 10 to the 36 years with something called hyper k that okay which is more of the same in the meantime what do people like me do well we look now for a bridge to the mystery of neutrino masses okay why neutrinos are massive and why are they so light this is a very it's not a very stable bridge yet because we don't know what's going on so so now the rest of the talk will be to talk about neutrinos so first the first thing about a neutrino it was it was not born from experiment directly it was born in the mind of a theorist okay which may which means that he was not believed by experimentalists for a long time okay it was the and coming from the south and you guys are in the south too it was the only elementary particle detected south of the mason-dixon line at the hanford reactor in the georgia south south carolina border okay and it was those were the original particles and and when they were followed in retrospect they always brought new physics with them in particular carol symmetry breaking so it has been a rewarding research area and now i wanted you to meet a few of the rewardees well no less than enrique fermi wolfgang paulie leon letterman mel schwartz and jack steinberg who passed away very recently okay all right and but there were more there was friend fred reiners ray davis kochiba and now those two in college are still alive okay so congeeta and mcdonald were the last two but there's another thing about neutrinos there's something i call the neutrino hall of fame these are people who basically made fundamental contributions but somehow died too soon or or were not understood at the time one of course is marijuana okay the answer is the other one is bruno pontecovo and it's maurice goldhaber and if you teach a course in experimental physics gold harbors measurement of the spin of the neutrino is probably one of the great gems of experimental physics through resonance scattering i mean it's just one of these incredible things then we have sakata another great genius but cole would die too soon lincoln wolfenstein those are also die too soon although okay so let's go to the letter and and i think this is interesting because of sociology so the famous letter of of um of pauli and he says they're radioactive ladies and gentlemen blah blah blah and he take tells so you don't have to read the whole thing you can read it later on you have a desperate remedy to save the exchange theorem which was the panel exclusion principle and the the fact that and then there was another problem the energy theorem okay and and he said they could exist in a nuclei electrically neutral particles we spin one half and do not travel with the speed of light i want you to know this because when you look at the end of the you know the summary of it all it's supposed to be very clear it was not and he said i do not feel secure enough to publish anything about this idea okay but only those who wager can win and then he says unfortunately i cannot appear in tubingen because i'm indispensable here on account of the ball etc we've gone pali was a strange person but you see what happened in his mind the pub the idea of a new particle okay which explains two things was even that he did not write it down because probably inventing a new particle to explain phenomena was just a not a macho thing to do because the macho thing to do was to explain everything with what you have very different from today when whenever you have something new you invent an infinite numbers that's true so paris two problems the pali exclusion principle which was the following 1930 there would have been very good measurements of raman scattering on the nitrogen nucleus and and the nitrogen nucleus this is before chadwick was made up of we knew how much it weighed so it had 14 protons and seven electrons because it renewed its chemistry at seven electrons okay so somehow those they had to be they had to be something different but that that you know that is that that is a bosa as the line intensities are different from from from bosons and fermions okay and then the second part so this was a problem that people were worried about the second part was the continued channel continuous energy spectrum of the beta decay electron okay and those were the two problems well so he calls it x and therefore now we have the so he looks at at the e coli little neutron by the way or yeah a little neutron or neutron i think he called it neutron by itself a nitrogen nucleus 14 proton per seven electron plus x and then here the dx in here and that was it now 1931 chadwick neutrons solve the nitrogen problem because basically the nitrogen nucleus the the atomic weight of 14 is actually seven protons and seven neutrons so we know it leads back to the way it is and the little neutron remains and in 1939 only 1939 says that pauli's particle is not in a nucleus it is created in an emitted during battery emission it took 26 years to find it okay and that that was found by [Music] oh okay all right so that was done by clyde cowan and and fried rhinitis longevity so first need about first thing about neutrino physics you need to live long so you have to have a certain longevity for neutrinos now the point the pontikova brothers next so bruno is the physicist guido is the biologist and angelo is the is the movie guy okay he's the one who wrote the battle of algiers and and okay and 1945 bruno proposed a ways to detect neutrinos which you hit neutrinos with with chlorine you get argon and you get electron fermi thought it was not practical because every at that time everybody went to fermi to double check because fermi was the guru all the time okay but ponte cover never published and the only time i met ponte covery he regretted this very much and and he had reprints made of his of his chalk river preprint i mean but ray davis uses it to count neutrinos from the sun at the home state gold mining lead south dakota pronounced lee which is now the site of dune the dune detector the sanford the detector and what happened he assembled a bunch of graduate students and he took out the argon okay because the argon that was produced was radioactive lived only about a month and therefore if you did it quickly enough you could count the argon and it and if you are a certain number of argon that would tell you how many neutrino hits there were okay you expect and davis finds one third of expected rate there it is the 97 comes in the supernova and the underground proton detectors that were being built just become basically neutrino detectors because a train of neutrinos was found okay then comes super k all right and now super k is a lot of material buried inside a mine except the money is that basically you drive to the mine horizontally because the mine is under a giant mountain and you drive into the mountain okay and those neutrinos come from cosmic rays and also from the sun okay and there it is so the from cosmic rays that's the you you would find the dk products when the cosmic rays hit the atmosphere you you would find a certain ratio of neuron to electron neutrino well you find more or less the same and i end you have the number so you have different type of things you have neutrinos that come through the earth onto the detectors from neutrinos that come from above and you you expected something you you expect equal number and you find okay and of course the reason is that these guys were traveling different distances therefore there was different observation and then there was a zenith eagle angle of dependence so they discovered two flavor of simulation in the tucson and the thing that was remarkable was that the angle that appeared in that oscillation was about 45 degrees in the process they they they confirmed they confirmed their deficit of electron neutrinos that davis had formed and therefore since they oscillate the only that means oscillating from one to the other that means you can distinguish one to the other so you have to give them a label and the only label that was available was basically their mass because you know in quantum mechanics once you have a label the label is a dynamical thing okay so next next come another guy the snow detector which is now this is under a mine in in in canada and and you you look at deuterium you look at dissociation by neutrinos all right and you look at neutrino electron elastic scattering and sure enough electron neutrinos oscillate the electron neutrino deficit is concerned is confirmed the solar electron neutrino flood is good is confirmed the the angle is not as large as the other one for for this but it is the salmon and the count of the it counts neutrino flavors and the late john balco who basically did not live on long enough to to be rewarded for this uh basically it was confirmed okay and then the large the the last mixing angle okay was basically the so-called reactor angle between the three neutrinos and it was first discovered uh into that by by a reactor at the border between france and belgium and then but it was really with accuracy it was the first chinese experiment where basically um he was he was uh he was a it really measured the angle with a great deal of accuracy and then the the korean detector reno found it as well and what it does is that basically uh these neutrinos produced in reactors etc etc i mean they are the question is that you get react to mixing angles you have an l over independence but in that case the reactor angle is is eight and a half degrees okay so what you have is a remarkable thing that basically you have the three mixing angle in a neutrino sector one of them is of the you know it's kind of reminiscent of the quark mixing angles you know the the quark mixing angles the largest one is the cabin which is about 12 degrees okay but the other two are very large so something is happening we don't know what so a little bit of theory and so the question is why are neutrinos so light well let's let me remind you a little bit about the neutrinos i guess we're running out of time so the three neutrinos occur as as the basically uh doublets one for the electron one for the muon what was one for the towel they all have a third component of this weak isospin under which they are doubling which is plus one half that's the upper component you could form for them a majorana mass which is neutrino neutrino but this has the weak isospin of because this each neutrino has weak eyes a spin one half and as everybody knows when you put two one half together you get either one or zero for the total but the statistics work here that you get one but if you give a lepton number to the neutrinos you get two that would be one kind of mass but it gets more complicated because you could add a right-handed neutrinos like for example the electron there's a left-handed neutrino you see the the electron that is in a doublet here that's a left-handed electron but there is a right-handed electron so you can do you can add the right and the neutrino which is i which has wick is a spin equal to zero just like the right-handed leg has also has a spin equal to z and then you could form what is known as the dirac mass but it has very different quantum numbers it does not violate an eptone number but it violates the weak by half a unit and now come comes the magic of this dirac and majorana unite okay to to provide an explanation as to why the neutrinos are so light and and the basic thing is what murray girl man call called the stupid little matrix uh basically what it is is that you if you take what happens you look at the myolar mass and this is the these these guys are dirac masses and you don't put the delta i which equals one so in other words okay you don't put any any majorana mass in there except for the for the very heavy for a very heavy one for the right-hander neutrinos and this guy here has basically a an eigenvalue m which is you see these two two matrix when you look at the trace of this of this is m but the determinant is small m squared so that means that one mass belongs is like capital m if m is much larger and the smaller the other mass is reduced by m squared over m so it's reduced by the scale of the electroweak interaction by this unknown scale and that is called the cecil mechanism okay where basically are the by uniting all of this stuff you get a you get very small separation mechanism okay so that's that is probably very important and that the mass the mass ratio is just the mass so it's so basically i think what happens is that there is a suppression mechanism that comes from the existence of a new mass scale we know nothing about okay that that is really the as they will say nowadays the takeaway okay all right so uh if you took if you look at the if you try to explain all of this stuff uh this suppression in the most sophisticated way you there is a limit on the mass of the neutrinos which is provided by the planck survey and this distance for milli electron volts okay and and that which corresponds and it starts to about a scale of 10 to the 16 gev now what is interesting is that that is the scale at which proton decay could become important so there is a big there is a coincidence that perhaps the scale that appears in a neutrino physics may actually have something to do with a scale close to planck scale and this is the dream that particle physicists are living with okay now so now let us go back and look at this neutrino mixing the the name of the lepton mixing matrix is called pmns p is poltikovo machi nakagawa and sakata three japanese ponte corvo with his with his reactions it was more like neutrino anti-neutrino oscillations whereas all of those that have been observed today are neutrino one flavor of neutrino to another flavor of neutrino but m s where under the sakada sakada sakata basically once they knew there were two types of neutrinos they started talking about mixing but okay and the question is that this object upm and s which is measured where those angles are mentioned measured in terms of when you look from a theory standpoint it's made up of two parts two unitary matrices was nearly unitary one that comes from new physics we know nothing about and one that comes electroweak physics okay the delta equals zero so it means that naively the experimental value of the angles could be basically a small component because the angles you know in the quark mixing angles angle are all very small so the black one will be small and then there will be a new angle so in this in this in this view the two large neutrino mixing matrix would be a characteristic of the new physics and from my point of view again when i was when i learned chemistry large angles meant crystals large angles meant crystal faces you measured angles between crystal faces etc okay so perhaps there is some sort of structure there but nobody knows i mean i have i have ideas of course but i will not be believed rightfully so because it's not it's not right so let me let me show you what the the present values are it's like that okay and okay so you see this guy here is small these guys are you know this is what we know okay all right now so the quark mixing matrix let me i i was in two bridges okay so the quark mixing matrix is a beautiful matrix which has been measured but it but it is the mixing between up quarks and down quarks okay that is the one and so we know both sides of the bridge here okay all right the largest angle there is basically uh the khabibo angle which i say is about 12 degrees now the laptop mixing matrix is that stuff we don't know what the heck it is on the other side okay and so this ponte cover maki nakagawa okay yeah but by the way patrick over's brother the guido if any of you remember the movie the battle of algiers which was a very famous movie at some point got an oscar et cetera he's he's the he's the director of that movie and um yeah so he was a talented family and the older brother was a biologist well known actually now so that is truly a bridge to the unknown so that is that goes again that is the kind and the good thing that happens okay is that now since we have the no what else can we do with it well the first thing is that the large angles allow for hope to explain the variant of symmetry now in a cosmology okay the the the conventional cosmologies that the universe started being symmetric matter antimatter symmetric and that the asymmetry that we see today has developed because of various mechanisms and one which basically uh preven well some were proposed but so far nothing has really been understood one is that we know that in this case there is a lepton number not that this is the total lepton number there is a phase which is which experiments tell you is non-zero this is this by the way is the convention that the particle data group uses and then there are two majoranas cp violating phases which we don't know these two experiments are going to be um well dune and and hyper k okay and and then this neutrino less double beta decay experiment which will be uh maybe the graduate students will see it but i will not see them um okay there will be so now the question is theoretical challenge and this is the last thing now the the device the model that was the greek people are playing with he's saying that the end we should think of the mixing angles for the leptons as being a beautiful dirac's view exactly that that matrix actually was actually proposed by an experimentalist called perkins so so then i'm defending myself because it's an experimentalist okay and then the noise the noise on this okay so you so you will you will have the standard model side will not contribute to that but it will it will con it will contribute to filling this zero okay so there will be a majorana crystal at the cut-off so is it simple or beautiful we don't know the answer so okay so i think it's i've i've filled your head so one way of finishing a talk like this is that you know i kind of pointed you to to various directions of this okay but all of them are question marks and the thing that is interesting which i did not mention too much is that some experiments right now uh are going to give us tell us something about the amount of this angle for example is going to be measured much more carefully right now i mean there is a by the juvenile the japanese and and perhaps do we'll see okay so so the idea the direct simple and beautiful maybe there is the neutrinos are trying to tell us there's something fantastic reading us because we don't know what it is so now let's turn to practical uses of neutrinos first use you don't need to build temples to the sun okay because we know where the sun is at all times you see in the old days people used to build these things to make sure that the sun would rise again because you know from the beginning you know the sun disappears and you never know so the the the priesthood became very very busy you know making sure that you know by building this the sun would gain to reappear but now i mean physics has taken the magic out of this the neutrinos are pure everywhere so this this is kind of a useless thing but nutri let me finish with neutrino chronology so the revelation of the neutrinos 1930 the detection 1956 which is two times 13 years later oscillations with a degree of of of certainty this was the the talk in 1998 okay is two two is four times ten to the seven years later okay and therefore as with my my old uh habit as a string theorist i look at the pattern and i say well maybe i should generalize this for the next big experiment the big experiment i see two to the first zero to the first second and third and then the next prime number is 19 therefore that that will be revealed in 2052. in the meantime enjoy the starry nights okay thank you very much okay now thank you very much pierre and since zoom is so bad at applause let's try to give you a little bit of applause here at the end thank you all right all right so we've come to the time when we can open up now for questions and i see we already have one question from pavel nadalski so pavel let me go ahead and get you unmuted okay you should be able to unmute leave yourself unmuted until you're satisfied with the answer okay uh hi pierce thank you so much for the wonderful yeah hi so i wanted to ask you uh uh in your opinion other viable uh mechanisms of uh electrowick symmetry breaking that do not involve my iranian neutrinos so in other words am i around engine is necessary for breaking electronic symmetry no no i don't think so no i mean the um the order parameter of the electro weak symmetry is uh well it it depends i mean for example if you want to you could forget about all this this stuff and just look at the majorana mass for a neutrino then you you need an order parameter that is transformed iso triplet not an iso doublet i mean the order parameter of the standard model is an iso doublet but if you put an iso triplet by hand okay then you will you will you will introduce a myomas by by its coupling okay but the problem now this would be a heaven for experimentalist because once you do this the the higgs guys that that that come in other words you know the the guys that come with the with the six triplet will one of them will have a double electric charge okay so that that's a paradise for experimentalists i mean because then i mean something with with charge two would be a would be thing but then you you have to explain basically why this why are is the mass of a neutrino so slow okay now now my rhino masses are necessary to explain barium asymmetry through leptogenesis i i did not have time to go into this but it is really necessary as is proton decay you know sakharov's way of of talking about proton decay which is baryon number violation well that's one but you see in a standard model b minus serum is is left invariant so if s is broken then b b is broken because b minus cell is invariant okay so that that is called leptogenesis that comes from that direction okay thank you you're welcome okay great yeah no thank you pavel um our next question comes from tom cohen and you should be able to unmute tom again leave yourself unmuted until you're satisfied with the answer yeah i i um kind of i have a kind of provocative question in the um in the run-up to the lhc i heard infinite seminars where the statement was made at one tev scale unitarity is violated new physics is guaranteed to pop up what's wrong with that statement well what well there are new particles coming in and the and they did come in and we there was a higgs there is you know all these things are fine the only problem that's not fine is that the mass of the higgs is is measured very accurately in fact you know some people have done it and but uh there is nothing oh it's a quantum field theory so it's okay unitarity is eventually violated but not at that scale yeah but who was surprised that the higgs was found but i okay i will tell you that there used to be a time when the department of energy and the particle data group was actually handing out one sheet poster on the standard model okay right if you look at that there is no mention of the higgs okay and the reason is because even though people like steve weinberg and others of course thought the higgs was there and certainly francois anglais and okay and basically a lot of people thought there would be some strong coupling or something that they you know etcetera etcetera okay that there was no there was no eggs they would they would okay but the higgs is there and so for some reason even in the in you know in the 1990s there were posters there were there were official reviews where the higgs there was a whole community of physicists who thought that there was technicolor that you got basically to to have strong coupling more strong coupling stuff and by golly i mean totally amazing as we go deep now we learned that the couplings are getting weaker not stronger i mean that and that of course is the magic of asymptotic freedom okay which which people did not think about been before so the existence of the eggs is there it's perfectly okay except why the heck is it that is it that that must and what people thought that if you added super symmetry supersymmetric particles within a given mass range you will explain why the eggs would be light well so the first the second part of the argument is there the higgs is relatively light okay but the first part of the argument there's no trace of supersymmetric particles in that mass range not to say it's not going to be there but if they exist it is not in that mass range the one thing that is kind of interesting about the value of the higgs mass is that if you look if you ex if you look at the higgs potential whose vacuum value gives you the higgs mechanism that potential the parameters of that potential vary with scale and if you go very deep in the ultraviolet there is a region with that value for that value of the heax mass where basically the lambda 5 4 coupling goes to zero which means that you would have a potential without retaining walls which means it will not be bounded from below so you have an unstable situation and that is the mathematical curiosity at the moment but but maybe it's telling us something very deep that's why i'm okay that's about as far as i can go and in the chat roberto vega commented that presumably this statement about the violating unitarity was under the assumption that the higgs mass was larger than one tev yeah yeah right yeah so the statement was either you discovered a higgs with low mass or new physics had to show in the form of new resonances yeah yeah and then uh pavel modelski noted that in the run-up to the lhc the concern was more about the naturalness of the standard model radiative contributions than about the unitary the standard model and he points out that that concern about the naturalness of the standard model nonetheless still remains to this day yeah it still it still remains we don't know but you see what i'm beginning to to think about except i have nothing nothing really clever to say is that whenever we look at the vacuum okay in the context of the standard model whatever it is this is something weird i mean the cosmological constant okay i mean to say the least right okay the the question is that the it seems to me that you know supersymmetry offers a very beautiful way of triggering electroweak breaking okay but it's still by some square mass squared becomes negative is driven in infrared or is being being negated but it's still it's a it's a conventional potential view okay so you're using the landau views of things but the question is that it seems that whenever the vacuum is involved there's something we don't quite understand i mean the the vacuum there are lots of vacuum expectation values everywhere there's something there and and i don't know i don't know what it is i mean that that is you know uh so probably experiment is going to be you know it's going to teach us something but right now back to the original the standard model right now does not challenge in an obvious one and obviously any of the fundamentals in the field all right tom did you have any more to follow up on there i'll give other people chance okay uh richard you have a question go ahead you should be able to unmute well uh i have a silly question thank you very much for the stimulating talk it's really brings forward questions which are deep in in my mind and one of them is the question on time uh the the physics theory tends to push the energy scale beyond our ability to measure is there uh any reason to believe that time will behave the same way at very high energies as a variable it's always factorized right in our yeah yeah well yeah there are other things right i mean when you look at quantum mechanics i mean as you said time is is completely different it's just a parameter that you put there with the schrodinger equation yes i mean in fact you don't even need the schrodinger equation if you're doing quantum information science you just live in here with space and and upload you know you have fun with it uh but uh yeah and yet there is special relativity where with all of a sudden time becomes space so space becomes time they become linked okay so uh i mean that again is beyond my my my pay scale i mean right now i think you just you you know use it as a uh i mean time by itself will not be impo what is probably important is the sequencing of things the notion of before and after but the question of of a continuous time maybe that only occurs when you have a continuous space coming up but before before there was a continuous time between before there was a continuous space maybe there was still a sequence of events but it was not necessarily continuous it could have been discrete okay but i don't know i mean you know those are as i said those are things you know so before the pandemic such thoughts you did it in the shower okay while you were taking your shower in the morning sometimes you thought about such such things with the pandemic you start thinking about such things a lot more often okay so i i i plead you know it's all the fault of the pandemic richard did you have anything you wanted to follow up on there oh it looks like you meet it again so i'll assume not unless you say otherwise all right any other questions for pierre so pierre can i ask you a question while we're waiting to see if there's any one last question here um so you you mentioned that we still really on the neutrino side of things we still need information from experiments and so and but you also kind of wistfully noted that some of these experience experiments are are likely beyond a single human time horizon at this point i guess if you could pick any one experiment and say i want to know the answer from that experiment right now what would it be and what do you what would you then do with that answer well okay so realistically okay the we're at the mercy of um you know well let's talk about the lhc for example okay and uh so it could very well be i mean this this is not a very clean business but it's it's looking for the new particles okay and if basically with new new detectors more computing powers power etc they have the ability to detect some anomalies i mean there are always anomalies in the data but that's the nature of quantum mechanics too that basically you can get you can have results all over the place and you don't know so but the question that becomes interesting if they detect some of these anomalies are linked to one another okay then of course it becomes interesting okay but now but if it is there are two game changing on things okay in our future one i think is is is you know the detection of proton decay now the as i mentioned in my one of my slides hyper k i didn't mention hyper k but hyper k will increase the the bound by an order of magnitude after many years of running okay that is one thing and the second one the second experiment which will basically uh tell you whether there is a majorana mass or not right is a neutrinoless double metallic tree which i i hardly mention and the neutrino s double beta decay tells you that you know it looks like beta decay except there are no there are no neutrinos okay and that was proposed in 1935 by well what's his name anyway 1935 and and you know nowadays we the experiments are many orders of magnitude away from possible detection mostly because of the nuclear physics it looks it looks like a very complicated very rare process but there is one day one expert so so those two experiments you know are game changers in the sense that they are attacking the last the global symmetry of the standard model b minor cell you know you can gonna be able so it challenges that but the one thing that is very very interesting isn't the actual measurement of the cp violating phase the dirac phase okay and that that you know nowadays there's just a hint for it okay and the effect of this on the overall picture of of of leptogenesis what it's called is just that the mixing angles in the pm and s matrix are large so if even if you if you have a relatively large angle okay but you have to to to look at its gauge invariant in fact you have to multiply it by the large angles and therefore it becomes larger so it has a chance of explaining the you know the number of matter minus antimatter per number of photons right which is the the figure of merits so but let let us be modest let's first hope that this we measure the amount of cp violation accurately in in in the laptop mixing and there's one more thing i did not talk about which is the hierarchy there are there are two competing hierarchies right now but that looks to me like it's a normal hierarchy where you have two light neutrinos and a little bit one heavier one but anyway that's the way it goes so but other than that there must be surprises interaction with dark matter yeah i mean you know the dark matter i mean we we you know it's there yeah and there's still and there's now there's seemingly larger more open question about what the heck's going on with the mu on g minus two for example is that well that that has a number of explanations yeah too many explanations on that one yeah okay because people have been studying that for for 40 years okay saying that this thing and what was holding up was the contribution of the strong interaction to the process and now of course with lattice simulation it seems to be converging so this is this would be maybe the you know there's maybe there's a new particle as far as the lhcb i don't know it's only three point my my i don't know it doesn't fit very well with anything i know beta sll is that what you're referring to no yeah yeah yeah then it seems unfortunately trying to put g minus two and b to sll together gets conflicting explanation no no no but they are serious to do that of course this is what theories do but you you know you just talk about i don't know it's also 3.1 i mean these people do the heroic work going from 2.6 sigma to 3.1 yeah okay i mean that that is truly heroic i mean and and these guys the g minus 2 they could really really be on the version of the discovery right because they're the level of of four yes before yeah and and uh and so but you know it's nowhere to make a business i mean to do a business the real ways to find a particle for god's sakes for example yeah yeah for example and so finding a particle indirectly is nice but it's not the full thing all right our last question will come from durdana which i think is beautifully symmetric so dardana why don't you go ahead and ask that question you put in the chat because it is provocative yeah well uh there were times with times when i was very interested in grand unified theory and i was always hoping that there will be a new uh experimental result that will allow us to figure out what is exactly we're doing wrong that we are struggling to actually have reasonable uh and practical theory that would unify all four fundamental forces and then we were sort of hoping that the ligo results will give us some sort of hint to what is going on to be able to at least bring gravity closer to the other three we're still so far off on that i'm not sure if things with lego experiment made things better worse so uh what do you think is the weakest point of the grand unified theory as it stands today that we are uh in such a deep mess when it comes to it well the problem is the number of parameters i mean you see once once you have a bigger group you're increasing the rank right i mean as you go you go beyond the electorate and the and the patterns are mathematically beautiful okay and but the question is that what whenever you know the only knowledge we have is the electroweak model the standard model so the path between the original when unified group and and and this and us is that we have many many scales of symmetry breaking because we have okay so we just have this the electro weak symmetry breaking and we don't even understand the mass of the higgs how it fits in this okay how come it is immune from radiative corrections okay so so now so you have to multiply this by force for example if you take su5 you you know su5 is the rank four thing okay so you have to get to it to su 3 causes you to cross you one so you have to you have to have in other words you have to invent in land house language new order parameters right to basically break this more and more so you're introducing more unknown and the one thing that we have found that we're not good at at all is breaking symmetries we know how to parameterize it i mean andrea and brad showed us how to do it and higgs okay but the the question is that we have we just a parametrization and we and so it's all coming down to the vacuum and i don't know uh so you know i just taught statistical mechanics right so in statistical mechanics you you have you have the thermodynamics stuff and and you don't have to know thermodynamics you just do statistical mechanics and you get thermodynamic quantities okay you know etc etc but if you know so the question i'm asking for example this is fantastic okay if i do a thermodynamics the one weird thing about thermodynamics is entropy the second law is weird okay and the second hotel tells you that the entropy can only either stay constant or go one way no not both ways and it's a little bit like time time seems to go only one way so you ask i mean this is pandemic okay but i mean it's crazy the the question is that uh uh now boltzmann and found the answer he said it's there's an underlying thing with avogadro numbers of of stuff in it okay and then we can use statistics to understand the going one way in terms of yes it happens but highly the notion of highly unlikely which is which is the statistical interpretation okay so right so the naive thing is that space time should be you know flat space time there's something underneath there we know that it's full of particle anti-particle pairs because we know when we calculate our corrections they work beautifully unless until we get to the goddamn higgs mass and this is where this is where i mean i'm at the end of my career right so i mean my i have tenure i'm okay my tenure doesn't depend on these things but the fact is that it's going to be very difficult to to make a you know to make a physical breakthrough okay there are times in history where it's very very hard i remember uh germain telling me the following stuff he said nowadays it's very hard to make a breakthrough this was the name in the 90s okay and i said why we said because written hasn't made a breakthrough he was talking about physics whereas the people who were born in the 1900s and were in their 20s in the 20s they were there to make breakthroughs because the breakthrough were happening just like that okay so it is a tremendous amount of luck and you know after all you know spectral spectral lines were there for a long long time people lived with spectral lines for a long time and then they got so used to it they didn't think and it was anything interesting so i don't know yeah yeah it's a difficult time it's a difficult time you know keep thorn when he was asked um about the ligo experiment he said he was disappointed and and the people ask him why he said well because it's consistent with general relativity okay that's a real theory he's talking i mean of course he was delighted but the question is that the experiment did not show any deviation and that's the problem we live under the shadow of einstein well i'm not sure if that's a i'm not sure if that's hopeful or hopeless but i don't know the exploitation is good but i mean the fact is usually these people clean up you know yeah but but there are are times so anyway but yeah maybe we do live now in a new era of problems that seem that we're you know taking for granted but we'll crack the walnut as it were on what new physics actually is between dark matter neutrino mixing and mass i mean i don't know perhaps we're living in that spectral lines error again yeah no but oftentimes you know read read marty klein plane because what what einstein was very good at was to pick out some something that he was unhappy with like for example in his paper of the electroweak effect he's very unhappy with the fact that there are there is there's the way of life wave nature which is the whole 19th century way okay and then and then matter on the other hand because einstein studied statistical mechanics like mad and he says it's all particles i mean okay and yet you have waves and he puts his finger on it and he and by the correspondence of the time he didn't think necessarily that special relativity was such a big deal but he thought that putting together a wave and particle together yeah and i'm not sure i mean if i did not exist i i'm not i still would have under the same reasoning because he never mentioned planks in the paper that's true it's very interesting anyway so okay now it is oh my goodness i think i owe it to myself i have a very old not very open 18 year old malt whiskey and i think it's a good time to yeah i i think there's no better reason than a good malt whiskey so here on behalf of the department and our community i really want to thank you for doing this so thanks again one more time for this one you're very my pleasure emulating presentation yeah and yeah no thank you pierre and you have a wonderful evening and we'll close out the event thanks everybody and have a good evening okay thank you all right bye bye