 Hello everybody, and welcome to the Latin American Webinar of Physics. Today I am going to be the host here. We are in the auditorium of Carlos Alansivia from the Universidad Catálica del Norte. And today we are going to have a very interesting colloquium. The speaker is going to be Maya Tortola. She is a Ramónica Han researcher at the Instituto de Quítiga Corpuscular in Alencia, Spain. And before that, she obtained her PhD in the same institute in the Instituto de Quítiga Corpuscular. And after that she had been postural research in the Instituto Superior Tecnico in this book. After that she did a postdoc in Hamburg University and then coming back to Valencia as a polygraph researcher and in the position that she is now. Also she has been awarded many times, one like a young researcher award in the Internet of Physics even by the Spanish Royal Physics Society. And recently she also got, she was awarded with the L'Oreal UNESCO Work for Women in Science. And after this presentation Maya, her colloquium is going to be about neutrinos. The title is Neutrinosignation from Evidences to Facts. And please, the people that is following the transmission in YouTube, you can subscribe to the channel if you don't like and also make all the questions in the YouTube channel, in the chat of the YouTube system. And Marian, welcome and please you can start when you want. Okay, should I share the place now? Or if you want to give a few words in the beginning of your colloquium. Okay, just to thank you for inviting me to give this colloquium, I'm very happy to present this colloquium. And then, yeah, you are free to ask many questions as you want at the end. Yes, I'm going to make the question at the end to not bring the rhythm of it. So then I'm sharing my screen. Okay, and then let me know if everything is okay. Yeah, it looks very nice. Okay, so should I start? Yes please. Okay, so as Roberto said, the title of my colloquium will be Neutrinosilations from Evidences to Facts. So here it is the outline of the presentation today. So I will start with a brief introduction about Neutrino Physics, about neutrinos and Neutrino properties. Then I will try to describe the first evidences that we have chronologically in history for neutrinosilations. Then once that the phenomenon of neutrinosilation has been discovered, then we need to treat it to do the simulation. So then we need to know which is the formalism to treat the neutrinosilations in vacuum. And I will describe this formalism. And also we will discuss how neutrinosilations are affected by the presence of matter in the different media where the neutrinos are traveling. So with all this information, I will present which is the current status of three-flavor neutrino oscillations with the determination of neutrinosilation parameters. After the discussion of the current status, I will also comment very briefly on which are the future prospects in neutrinosilations. What can we expect from the next generation of neutrinosilation experiments? And just with a couple of the slides, I would like to discuss how this situation of three-nutrino oscillations could be modified in the presence of new physics beyond the standard model. So I will start with these introductions. So maybe this is very basic for all of you just to recall what are neutrinos. So neutrinos in the standard model, as you know, they come in three flavors corresponding to each of the charged leptons, electron, muon and tau. We also know that in the standard model, they are organized in SU2 doublets together with charged leptons. And contrary to what happens with, for instance, electron, muon and tau, there are no SU2 neutrino singlets. That means that neutrinos in the standard model are only left-handed while anti-neutrinos are only right-handed. And another fact about neutrinos in the standard model is that they are strictly massless. So there is no mechanism in the standard model that allows us to give some mass to neutrinos. What else? Why we care so much about neutrinos? Why they are so important? So first of all we can say that neutrinos are very relevant because they can prove environments that are not possible to reach with other techniques. So for instance we can get neutrinos directly from the core of supernova explosions or neutrinos coming directly from the core of the sun. While this is not happening with photons, photons that are produced in the core of the sun are trapped inside the sun for 10,000 years while neutrinos escape straight to the earth. On the other hand, the role of neutrinos is crucial to understand the evolution of the universe. And they have a very relevant role, for instance in the BigBug nucleosynthesis or in the formation of structures. Neutrinos could also help us to explain the matter-antimatter asymmetry of the universe that has been observed through the leptogenesis mechanism, for instance. And finally they could also be one component, not all of them, but a component of the dark matter of the universe. And as we will see in this talk, they have provided the first evidence for physics beyond the standard model that it is the proof that neutrinos that they have amassed. So we see that neutrinos are very important, but however there are still, we know a lot of things about neutrinos, but there are so many open questions in neutrinophysics that we need to solve. Okay, so then after this introduction I will start in describing the evidences we have for the presence of neutrinos relations. First of all, the first indication came in 1968 from the observation of solar neutrinos by Raymond Davis in the home-stake experiment. So this experiment was using perchloroethylene, a solution with chlorine, in order as a target to detect the solar neutrinos with this reaction here in the slide. And Davis was measuring the number of electron neutrinos that were arriving to the detector, and he found that only one-third of the neutrinos predicted by the standard model of the sun were detected. Okay, and thanks to this observation, to the first observation of solar neutrinos, Raymond Davis was awarded with the Nobel Prize in Physics in 2002. Afterwards, this result, this indication was confirmed by three other radiochemical experiments, Galax, GNO and Sage in Italy and in Russia. And these experiments they were using instead of chlorine, they were using gallium as the target material to detect neutrinos. So here again it is the detection process that these experiments were using, and this time they also observed a deficit in the solar neutrinos with respect to the predictions of the model of the sun. However, in that case, the deficit was around 50%. So later on, more sophisticated detectors were designed, as for instant cameo-candle in Japan or super cameo-candle, the extension. This experiment here, there is a picture of super cameo-candle that it is still working. And this is a five kiloton water chain of detector, and since they use, given the process they use to detect neutrinos, here it is this neutrino electron scattering process. The super cameo-candle is sensitive to all neutrino flavors. If you remember, here in the previous slide, we saw that, for instance, in the home stage experiment, only electron neutrinos can be detected, also the same for gallium, but in the case of super cameo-candle, all the different flavors, electron neutrinos, neon neutrinos, and all neutrinos were experiencing this process and were detected. And the most important feature of this experiment is that it is a real-time detector. That means that for each neutrino event, it is possible to associate a given to reconstruct the energy of the incident neutrino as well as the arrival time to the detector. That this was not happening, for instance, with the radiochemical experiment we have seen in the previous slide. So super cameo-candle, they measured the spectrum of electron neutrinos, or solar neutrinos, with respect to the energy. We have here the plot on the left, where these blue data points are the number of events they observe for each reconstructed neutrino energy. And they also, since it is a real-time detector, they can also measure the flux of neutrinos depending on the time of the year. And as you can see in the plot on the right, super cameo-candle observations are consistent with the flux at what can expect given the eccentricity of the orbit of the Earth. And once again super cameo-candle was detected less neutrinos than expected. You see here in the plot on the left, they are plotting the data over the standard solar model predictions. And in that case, they were observing like around 40% of this prediction. So putting all these results together, this gives rise to the known as solar neutrino problem. So you see here in this graph, it is shown in this case for the home state experiments, the gallium experiment and the super cameo-candle experiment. So we have the number of neutrinos predicted by the standard solar model in the left and in the right, the number of solar neutrinos detected. And as you can see, the deficit is different for each type of experiment. 30% for home state, 50% for galaxy and genio and sage, and 40% for super cameo-candle. So why this deficit? So first people, they start to think that there should be a problem with the theory. Meaning that either the standard model of particle physics or the standard solar model, they are wrong. So this was one of the hypotheses. Another hypothesis was to consider that there was some, the experiments were wrong. But all of them were having these puzzling results. So it was a very strange that all the experiments had problems. And the third possibility was that perhaps something was happening to neutrinos in their way from the core of the sun to the detector at Earth. And also another question was why there are different results for different experiments. So here you should notice that different types of neutrinos are observed in each kind of experiments. And for instance, as we have said before, radiochemical experiments with chlorine and gallium, they measure only electron neutrinos while super-K measures all the different neutrinos. And there is another difference between these experiments, and it is the different energy range sensitivity. So according to the process the experiments used to detect neutrinos, these processes have a different energy threshold. And for instance, the chlorine experiment has a threshold around 0.8 MeV. For gallium the threshold is lower, 0.2, while for super-Kamio-Kande the experiment is only sensitive to energies above 5 MeV. So you can see that the different results might be related with the fact that different type of neutrinos are observed and also different energy ranges. But we had this problem. It was a very long-standing problem. And then there was another experiment designed to try to find out what was happening with solar neutrinos. This experiment was the Zagburi Neutrino Observatory Snow in Canada. So here is a picture of the experiment. This experiment contained 1 kiloton of heavy water and was located 2 km deep in a mine in Zagburi in Canada. So the novelty of this experiment is that it is sensitive to only neutrino flavors through different reactions. So for instance, it detects neutrinos through these three different processes. So the first one is elastic scattering. It's the same as in super-Kamio-Kande. So all flavors are sensitive to this process. But then given that they use heavy water, there is deuterone inside, and then this experiment can detect neutrinos through processes of chest currents and neutral currents with the deuterone. And for instance, we have the chest currents where only electroneutrinos are sensitive to the process, and neutral currents where all neutrinos have the same strength. So the process, the cross-section is the same for the three different neutrinos, electron, muon, and tau-neutrino. So using the flux, they have measured from these different channels. So here you have in this graph on the right where they are plotting the flux. They measure for neutral current in blue, for elastic scattering in green, and for chest current in red. And from this experiment we can learn. So first of all, you can see that the blue band is consistent with this band with dashed lines that corresponds to the prediction of the standard solar model. So the first result is that the neutral current flux, the sum of all neutrinos, is in agreement with the predictions of the standard solar model. So it seems there is no problem with the standard solar model. And on the other hand, we can see that only 30% of the solar neutrinos produced as electroneutrinos arrive to the earth as electroneutrinos. So we have that from the full solar neutrino flux arrives to the earth like one-third electroneutrino, one-third muon neutrino, plus one-third tau neutrino. So with this new result, we can just combine with the other experiments we have seen before. So we have added the column corresponding to snow for a sensitive to charge current, only an electroneutrino, and also the columns of the snow corresponding to the detection of neutral current that is sensitive to all frivolous. So we see in the columns at the right, we see that really all neutrinos are there. And therefore, what is not confirmed was that there was happening a flavor conversion in the solar neutrinos from electroneutrinos to the other flavors. And this solved the long-standing solar neutrino problem. And thanks to this result, Professor Art Macdonald got the Nobel Prize in Physics in 2015. However, at that time, it was clear that there was a flavor conversion in the solar neutrinos, but it was not clear what was the conversion mechanism. So at that moment several mechanisms were allowed. Neutrinosilation was one of them, but it was not the only one. So we had to wait until CAMLAMP, the reactor experiment CAMLAMP, that really singled out neutrinosilations as the solution to the solar neutrino problem. So let's see what is this CAMLAMP. So it sounds strange, but the experiment who really solved the solar neutrino problem is a reactor experiment. So CAMLAMP, as a reactor experiment, uses inverse beta decay as a process to detect the electron and the neutrinos produced in nuclear power plants. CAMLAMP was designed to be close to 55, around 55 commercial power reactors in Japan. Here you have the map of the different power reactors in Japan and the location of the CAMLAMP detector. And it was designed in such a way that the average distance to the detector was of around 180 kilometers. And this baseline was especially chosen in order to prove the solar neutrinosilations. So in December of 2002, this experiment CAMLAMP obtained the first evidence for electron neutrino disobedience. So you see here in this plot, this is the number of events observed in CAMLAMP as a function of the energy. And you see there is the points, the data points, these crosses show a depletion in the number of electron and neutrinos observed around from 3 to 5 mEV. So the solid line above should be the prediction with the oscillations while the points show a deficit in this region. And this result was the one that really conferred that the commercial mechanism for solar neutrinosilations. However, there was no Nobel Prize here. So I find it's a bit not fair, but they decided the Nobel Academy decided not to award this CAMLAMP collaboration. Okay, so in parallel to the solar neutrino anomaly, there was another anomaly this time in the atmospheric neutrino flux. So as you may know, cosmic rays interact with the Earth's atmosphere and they produce pions and k-ons. And these pions and k-ons, they decay, generating m-ons and neutrinos. So according to the processes of the decay of pions, then what we would expect that the number of m-on neutrinos and anti-neutrinos divided by the number of electron neutrinos should be around 2, okay? This is a bit of an approximation because it depends on the energy, but okay, for low energies this should be more or less the ratio, sorry. The ratio one should expect. However, there were several experiments looking for atmospheric neutrinos. Even they were looking just as a background for other purposes. For instance, for searching for proton decay, but they were trying to monitor the atmospheric neutrino flux. The experiments, most of them, for here this small graph in the bottom, for instance the IMB experiment or the cameo-cande, super cameo-cande, they were observing less a ratio smaller than 2. So they were observing less m-on neutrinos than expected. And this result was known as the atmospheric neutrino anomaly. So in 1994, the cameo-cande experiment in Japan finds that this m-on neutrino deficit that had been observed at several experiments is not constant, but it depends on the distance that has been traveled by the neutrino. So here, for instance, in this graph you have here, less neutrinos were observed coming from downwards than was to the detector, while the number of neutrinos coming from above the detector was consistent with the predictions. So this indicated that neutrinos traveling longer distances, so the ones that traversed the Earth, something was happening with these neutrinos that were not arriving as m-on neutrinos to the detector. So finally, four years later, the super cameo-cande experiment improved their sensitivity and they discovered, they improved the statistics of this analysis and they finally discovered the atmospheric neutrino oscillations in super cameo-cande. So here in this graph, you see, for instance, the results they got for the electron neutrinos at left, where you see that the data points, the results are consistent with the predictions, the predictions in absence of oscillations in blue, this blue Instagram, but this was not happening for the m-on neutrinos. In the case of m-on neutrinos in the right plot, you see that there is some agreement between the data points and the predictions only for cosinos of the zenith angle larger than zero. For values of the angle smaller than zero, that means the ones that come from below the detector, there was a deficit. There were less neutrinos than predicted. Since the number of electron neutrinos was totally okay, but the number of m-on neutrinos were disappearing, so this was given a hint that the oscillation channel was from m-on neutrinos to tau neutrinos, since tau neutrinos were not detected at super cameo-cande. And as a first evidence for neutrinos oscillations, because this was previous to the solution of the solar neutrino problem, this is supposed to be the first evidence for a non-zero neutrino mass. Okay, and for this discovery, Prof. Kajita shared with Art MacDonald the Nobel Prize in Physics in 2015. So after this historical introduction, then I would like to discuss a bit of the formalism of neutrinos oscillations. We will start with neutrinos oscillations in vacuum, and later we will see how this formalism is modified in the presence of matter. Okay, so neutrinos oscillation is a quantum mechanical process phenomenon that is a consequence of neutrinos having a mass. Because since if neutrinos have a mass, then in principle the neutrino states, the neutrino eigenstates with definite flavor, the ones that are produced in the electro grid processes, in general they can be different from the neutrino states with definite energy. Okay, and these two different types of eigenstates, the flavor eigenstates and the mass eigenstates, in general they are related through a mixing matrix U as you have here in this relation. All over the talk I'm going to use the alpha label to refer to the weak eigenstates, electroneutrino, myoneutrino, tau neutrino, and these Latin indices K here to refer to the mass eigenstates and neutrinos. Okay, then what happens in the evolution of neutrinos is that at the beginning we have the production processes, that for sure they are electro grid processes, then they produce the flavor neutrinos, new mu, new e, new tau, and then they propagate as eigenstates of the Hamiltonian, as in states with definite energy, so they propagate as new one, new two, new three, and then afterward when we detect the neutrinos back, since we need to detect it through their interaction with just electrons, through electro grid processes, then we recover the flavor eigenstates, new mu, new tau, and new e. So we have seen that these flavor eigenstates are in general linear combinations of these mass eigenstates, in the case of two-neutrino mixing, okay, only two-neutrinos, two-flavor neutrinos, that is a good approximation in some cases, then we have that this mixing matrix U depends only on one angle, when this is a rotation only with one angle theta. However, in the more realistic case, when we consider the three-neutrino, the three-neutrinos, new mu, new tau, then we need to consider this matrix as a three-by-three matrix, and in that case, we see that this matrix is described by three rotations, this means three angles, and one phase. So here, usually, this neutrinomics in matrix is presented in this parametrization with these three different rotations. So in the first piece, you can see here, it's a rotation with an angle theta to three, and this is the angle that can be proved at atmospheric and accelerator-disappearance experiments, as we will see later, then in the middle, the piece in the middle, we have the theta-1-3 mixing angle and this delta phase, and this mixing angle is proved in sorbetion reactor experiments, as well as in acceleraton experiments, that can also prove the delta phase. And finally, the last part, the last ingredient of this mixing matrix is the rotation with the angle theta-1-2, that it is also known as the solar mixing angle, and that is measured in solar experiments in the reactor experiment camera. Okay, so in order to understand what is happening with neutrinos, it is very useful to draw this picture. So as we have seen before, we have the neutrino source with an electro-whip process, then the neutrinos propagate, and then they are detected. So we can split the evolution of neutrinos in these three different steps. So we have already seen that flavor neutrinos are combinations of mass neutrinos, so the production, the part of the production, we have that the flavor neutrinos are produced as a coherent superposition of these massive states. So we have the first piece, the last piece will be the detection, so then in the detection we need to project back over the flavor-again states, so this will be this part, we need to use these mixing matrix, and what happens with propagation. So this part is very easy to understand what is happening. In that case, we need to calculate the neutrino evolution. To do so, we will use this very basic quantum mechanical equation, the Rodinger equation. Okay, and then we see that if we wrote this equation in the neutrino mass eigenstate basis, so where the Hamiltonian is diagonal, then we have that the simple solution of the Rodinger equation is given here, where we calculate the evolution of the new J state just adding a phase proportional to the energy. Now if we use a couple of approximations, for instance the equal momentum approximations, and we take also into account that neutrinos are relativistic particles, so we can approximate the time by the distance, because in some experiments we don't have a measurement of the time, since the production to the detection, but we always have a measurement of the baseline, that is the distance between the production and the detection of neutrinos. So it is useful to use a baseline instead of time. So then working a little bit this phase, then we see that the evolution of this mass eigenstate, the new J, then depends on a phase that is proportional to the mass of the state, the energy and the baseline and it is proportional to the energy. Okay, so then we just plug in this new piece that takes into account the propagation in the middle of this picture, okay, and we see that this piece takes into account that different propagation phases for every mass eigenstate. Okay, so for a different mass we will have different propagation phase. Okay, so now we have already three pieces. With these three pieces we can calculate the neutrinosilation amplitude, so we need to plug the production part, propagation part and detection, and then we get this very simple expression for the neutrinosilation amplitude. Then to calculate the neutrinosilation probability we just need to do the square of this amplitude and then we get this very well known formula for the neutrinosilation probability that this is in general for a number of n neutrinos, okay. And we see that the presence of complex phases in the matrix U, for instance, induces Cp violation, meaning that the probability for the channel mu alpha going to nu beta in general could be different from the probability of anti-neutrino alpha going to anti-neutrino beta. And it is also remarkable that oscillations at the end, after doing the calculation, we see that oscillations do not depend on the absolute neutrino mass scale, but they depend only on the mass square differences, okay, as you can see here in the argument of the trigonometrical functions. Okay, so we have seen that besides the missing angles, oscillation probability depends also on the mass square differences, okay. So with three neutrinos, now we consider three neutrinos, there are two new parameters, two mass square differences. So one of them is labeled like delta M31, and is the one that can be proved in atmospheric and long baseline experiments, and the other one is known as delta M21, and is the one that can be measured in solar experiments in Kaplan. Okay, that one is positive by definition, by the definition of the formalism, but in principle the other one, the first one, the delta M31, would have both signs, could be positive or negative. And according to the sign of this delta M31, we have two possible ordnings for the neutrino mass spectrum. So here you have here at left the one labeled as n all, that means normal ordering. So here you see that it is called normal because the electron neutrino is mostly the light one, as happens for the just leptons. Electron is the light one, okay, the lightest one. And on the other hand, for the inverted ordering, that happens when delta M31 is negative. In that case, the electron neutrino is one of the heaviest, one of the heaviest neutrinos, contrary to what happens with just leptons. And this is why it is known as inverted ordering. So for many years we didn't have any idea about what is the true ordering of neutrino masses, but very recently we had from the oscillation experiments we see that they favor normal ordering now at the level above three sigma. It is still not conclusive, it is not a discovery, but it is true that the neutrino oscillation data are showing a great preference for normal ordering. Okay, so after seeing that we are going to discuss a little bit the properties of neutrino oscillation probability in the simplest case, that is the two neutrino mixing. So we have seen that in the case of the two neutrino, this is the mixing matrix. Okay, and then if now we apply this very long formula, we have seen that it was totally general. Now we apply this formula to the case of two neutrinos. We get this expression for the probability of oscillation between nu alpha and nu beta. This is a very simple probability. Okay. And then we can see, for instance, there is an oscillation phase. Okay, there is the mixing angle theta is defining the amplitude of the oscillation while the mass square is the parameter controlling the oscillation phase. So you have here the value for the oscillation phase and depending on the value of this phase, one can observe three different regimes in neutrino oscillations. So first of all, for short distances, meaning that the phase, the oscillation phase is very small, smaller than one, then oscillations don't have time to develop. Okay, so in this picture here will be just the beginning of the graph. So the distance is so short that oscillations have not started yet. So the probability is close to zero. In the second regime, that is known as long distance, then this oscillation phase is close to one. And in that case, oscillations are observable. So we correspond here to the first oscillation maximum here in the plot where it is labeled as long distance. And finally, we have the regime of very long distances when the oscillation phases are very large, much larger than one. And in that case you see that there are very fast oscillations and then at the end provided that the detectors have some limited energy resolution, they cannot resolve these very fast oscillations and at the end the result is that oscillations are averaged out. So the frequency term is averaged to one-half. And finally we have that the oscillations probability can be approximated by one over two signals squared to theta. So this is for a vacuum. So now let's see how oscillations are modified once we consider the presence of matter effects. So when neutrinos pass through matter, they interact with the particles in the medium and then they feel an effective potential due to this interaction with the medium. So this was proposed first time by Lincoln 1, first time in 1978. So in principle neutrinos may experience just current processes with the just leptons in the medium and also neutral current processes. So using a simple for fermion interaction Hamiltonian one can derive exactly the which is the potential, the effective potential that neutrinos feel when they travel a medium and then here I'm just giving a short summary of how to calculate this. So in principle in an ordinary matter we are only considering as fermions with neutrinos interact electrons, protons and neutrons. So considering this ordinary matter and also a non-relativistic and polarized in neutral medium then one can obtain this value for the effective potential in matter for neutrinos. So it is here, it is a diagonal matrix where first entry corresponds to the potential for electron neutrinos, second neutrinos and third-down neutrinos. So as we can see all the electron neutrinos are sensitive to charge current because there are no millions or towns in ordinary matter so this is why only the density of electrons appears in the first entry of the potential while the neutral currents have the same effect for all flavors. So we see that the neutral current part that is corresponding to the density of neutrons appears equally in the three entries of the matrix. And however since it appears in the three entries of the potential then at the end since what is important for oscillations is to have the relative phases then we see that this neutral current potential has no effect whatsoever on the neutrinos oscillations in matter. So this is the calculation corresponding to neutrinos if we are studying anti-neutrinos then we need to change the sign of the potential. Okay so now that we have calculated the effective matter potential then we can see how oscillations are modified. Here I'm going to talk only about the case of constant density. For cases with... if anyone is interested for cases of varying density then I can give some references. So indeed this case of constant density is indeed a good approximation for oscillations in the earth crust where the density is not varying much. So in that case in the case of constant density the oscillation probability can be calculated with the usual expression we have seen in vacuum so you remember the expression with the senous square of 2 theta senous square of the oscillation phase but as you can see here we are changing instead of putting the vacuum parameters theta and the mass square there are some effective matter parameters this theta m here is the definition and also there is this delta capital M squared the mass squared effective in matter. Okay so we can study for instance how this effective mixing angle in matter this theta m changes with the density in a medium. So we see that for instance for the... sorry when the value of A is much smaller than cosinous of 2 theta then if we do the calculation for theta m theta m is very close to the mixing angle in vacuum so you see here in the left of the plot so for this part of the plot when for small values of A then oscillations happen like in vacuum. On the other hand for the other part of the plot when the matter effects when A is much larger than cosinous of 2 theta then there are very strong matter effects they suppress oscillations and we have that effective mixing angle in matter is close to pi over 2 and what happens in the middle? In the middle there is a resonance so when the A that is nothing but a function of the potential energy and the mass splitting when this A parameter is exactly equal to cosinous of 2 theta then it happens a resonance there is an enhancement of the mixing angle and this is what we know as MSW effect and this resonance condition is satisfied for neutrinos provided that the mass splitting is positive or for anti-neutrinos for negative mass splitting so how do we translate this effect in solar neutrinos? we can calculate the value of this A parameter in the centre of the sun A is equal to this and since we know from solar data theta is equal to 34 so we see that the MSW resonance will happen at A equal to 0.4 for a energy resonance of 2 MeV so for solar energies lower than 2 MeV oscillations will happen like in vacuum and for energies larger than 2 MeV there will be a very strong matter effect and this will be the value of the oscillation probability and this will explain also why we accept a different deficit in the different solar experiments I think I am running out of time so maybe I will skip this so matter effects are also very important for understanding neutrinos because also some resonance might be observed in the solar neutrinos preparations so I will switch to three flavour neutrinos oscillations so currently we have evidence for neutrinos oscillations in atmospheric, solar, reactor and accelerator experiments and each experiment is sensitive to different missing parameters we have seen already this picture before so with a mixing angle sensitive in atmospheric accelerator, reactor and solar okay so now I will focus on the solar plus camlan data so solar experiments have measured neutrino disappearance for over 50 years so different experimental techniques and different energy ranges and they have provided measurement of the solar neutrino spectrum here you see the data for the different experiments boraxino, supercamiocandes, snow homestec, there are the values for the different experiments they have also measured the data symmetry and very important as I explained before camlan experiment has provided a very precise measurement of the oscillation frequency so using all these experimental results one can try to reconstruct these oscillation parameters theta one two and the mass splitting two one and then we get these results so in black you have the allowed region from solar experiments in blue the region that camlan predicts and then the overlap of the two regions is what we call the global region of the oscillation parameters okay so now I'm going to move to the big sector so in that case we have discussed before the supercamiocand experiment but nowadays we have observations of atmospheric neutrinos in other experiments like deep core ice cube that is a small part inside ice cube in the south pole and also the experiment antares in the mediterranean they also measure the highest part of the atmospheric neutrino spectrum so using their data one can try to infer the values of the oscillation parameters in the atmospheric sector theta two three and then time three one so here I'm plotting the allowed regions for these experiments so here when talking about the atmospheric sector I will always show two panels so the first panel corresponds to normal ordering you can see there and the second panel to inverted ordering so in this sector besides the atmospheric experiments we have accelerator neutrino experiments that were designed in order to confirm the oscillations of serving atmospheric experiments so there are there were three experiments of these types because one of them is already off so one was Minos the one that has already is not running anymore so there is Minos in the states in Japan and Nova in the united states as well okay so there are three different experiments looking for measuring the oscillations of of neutrinos after a distance between 300 kilometers to 800 kilometers from the production so the results of this experiment they have confirmed that oscillations happens of neutrinos and the results are consistent with the measurements of atmospheric data so here they are the regions of the atmospheric parameters that what we can calculate from these experiments Minos plus T2K using the neutrino and antineutrino channel because they run in the antineutrino channel in the antineutrino channel and for Nova only neutrino data since antineutrino data has been published very recently only and in all cases we see that the experiments prefer theta to 3 very close to maximum value so we can also combine the results of atmospheric experiments with a long baseline and then we get the results for normal ordering and inverted ordering we see that in black the result only for long baseline experiments and in blue once we combine with atmospheric as you can see the precision on these parameters is now a day dominated by accelerated data so finally the last piece of the neutrino mixing matrix the theta 1 3 mixing angle so I have to say that this is the most recent measurement it is known only since 2012 ok and it has been measured thanks to a new generation of reactor experiments like Daya Bay in China, Dabel Cho in France and Reino in Korea and this new generation of reactor experiments have some properties so they use more powerful reactors compared to previous reactor experiments they have very large detector volumes and they use between 2 and 8 detectors located at different distances of the power plants so using the data from these 3 experiments we can also reconstruct the theta 1 3 mixing angle and then we get this result here for normal ordering and inverted ordering so you see the regions obtained from the Dabel Cho data Reino data and Daya Bay and as you can see the precision nowadays is dominated by Daya Bay so putting together all these different pieces from solar sector, atmospheric sector and reactor we can prepare a global 3 neutrino analysis combining all the, it is floating the synergies between the different data samples so this here we are showing the kai square profiles for all the 6 different parameters that we measured, the 3 mixing angles and the 2 mass splitings and the delta phase so as I said before in our days the data are disfiguring inverted ordering at 3.4 sync so we are getting very precision measurements for the oscillation parameters here I'm showing the best fit value for all these parameters and also the 3 sigma range and as you can see the precision are really astonishing going from 1% to 5% and also for the delta cp phase that one year ago we didn't have a clue about the value of the delta cp phase now we have hints about the it has a maximum value so close to 3 pi over 2 and also we are improving the precision very fast so Roberto how I'm going with time it's okay Roberto with time okay so I still have a couple of slides so I wanted to discuss what can we expect from the future generation of oscillation experiments so first of all in some parameters we can expect only improvement of precision like the solar mixing angle reactor mixing angle and some mass splitting but in some other parameters we need some more information for instance we don't know very well the octane of the atmospheric mixing angle the sign of the delta m31 mass splitting if it is normal or inverted and also the value of the cp phase so we can expect some improvement in the precision of the parameters from t2k from the new upgrade of t2k Daya Bay and from Juno reaching precision below 1% for all parameters so also concerning cp violation we can expect very good measurements by NOVA in the upgrade of t2k so they can be able to observe cp phase at the 3 sigma level in 2024 or 2026 however we want to have a discovery of the cp violation at the level of our 5 sigma then we need to wait until the next generation of experiments like Dune or HyperGate only Dune and HyperGate will be able to provide the sensitivity and concerning the mass ordering we might expect some improvements coming from Orca in the Mediterranean from NOVA and also from the Reactor Experiment Juno so just a couple of more slides I would like to mention that here I am describing the standard 3-neutrinosilations scenario but things may happen if we deviate a little bit of this scenario we will see some improvements if there are more neutrinos so we know from the invisible decay width of the set at LEP that the number of light neutrinos should be around 3 however there are some experimental hints that point towards the existence of a fourth sterile neutrino so nowadays there are evidences from accelerator experiments like LSD and Miniboon there is the reactor anomaly and also the equilibrium anomaly of the existence of sterile neutrinos of mass of the order of one electron volt however if one performs a global 3 plus 1 analysis taking into account not only these hints here but all the data valuable then we can observe a strong tension between the experiments that observed a hint of sterile neutrino and the ones that don't observe like ice cube, supercambiocandy minus or minus plus so there is a strong tension there is an inconsistency between different experiments and on the other hand there is a tension with cosmology because cosmology provides some information about the sum of neutrinos masses and also the number of relativistic degrees of freedom so the sterile neutrino hypothesis would require a sum of the neutrinos masses larger than one electron volt and a number of effective degrees of freedom of order four cosmological results points to the sum of masses below one electron volt and also to the effective numeral degrees of freedom close to three so you see that these hints are in tension with other experiments other oscillation experiments and also with cosmology so more work is done in this there are a lot of experiments trying to find out what is happening with sterile neutrinos but we may have also some the presence of some new physics beyond the standard model that may affect our current picture of neutrino oscillations so for instance there can be non-standard neutrino interactions that they appear in models of neutrino masses and these non-standard interactions may affect the precision on the oscillation parameter as well as the sensitivity reach of the upcoming experiments so for instance if we consider the presence of this NSI in solar neutrinos we may get a degenerate solution with mixing angle larger than pi over 4 or the presence of NSI may give rise to degeneracies in the measurement of theta-2-3 in dune likewise one may have a non-unitary neutrino mixing that is a consequence that most models of neutrino masses where there are extra heavy states and then as a result of these extra heavy states a large n times n mixing matrix that could be unitary but in general the light 3 by 3 mixing is not unitary unitary in general so if one considers the part 2 from the unitaryity of this 3 by 3 mixing matrix then one may have for instance some degeneracies in the determination of the delta-cp phase in dune so now I'm going to the summary sorry for this delay so we have seen that very important discoveries on neutrino physics have happened along the last century and very importantly they have provided the first evidence for physics beyond the standard model so neutrino simulations are nowadays a phenomenon that it is very well established and has been observed at several experiments with natural neutrino sources as well as artificial neutrino sources the oscillation parameters have been measured very accurately with precision smaller than 6% by the combination of different experiments we have for the first time some indications in favor of the normal mass ordering and also indications on the preference for a maximal cp phase in the future, in the near future oscillation experiments will help to solve the current announced on neutrino oscillation and will also provide precision measurements of the oscillation parameters below 1% in the last part of the talk we have seen that there are some indications pointing to the existence of sterile neutrinos at the electron volt scale although there is no consistent picture yet there are some tensions between other experiments and also with cosmology and also we have seen that the presence of new physics scenarios beyond the standard model may give rise to the partures of the current oscillation picture and this is very interesting because these scenarios could be proved at future experiments and that's all, thank you thank you very much, Mariam it was very nice your I'm sorry for the too long so for the people that are following the transmission here live please write your questions in youtube so we are receiving many ones now so for the people now in the hangout please the one that participates in the session can ask questions, meanwhile I'm also asked here in the audience in the auditorium they want to address some questions to Mariam if there is a problem with the language you can ask and then we make a very fast translation for the people that don't speak Spanish and so please, the first one can unmute him or herself Roberto, I have removed already the screen share or it is already there I'm prepared, you can present your webcam or if we need it, you can change your slides for instance I'm going to start, I have some questions for you Mariam, if you can tell us a little bit about what is the future in the neutrino anomalies is there a hint of any stuff that is known in the neutrinos like all the anomalies beyond the one related with oscillations or the one related with like you mean the sterile or which one sterile is another type of interaction in the neutrino sector and in so far sorry? there are some hints in the experiment so far the only anomaly that it is present in the data is the one related with the like sterile neutrinos so it is I put it in the slide you could see because I was very fast so besides lsnv, minimo, the reactor anomaly the gallium, now there are two other reactor experiments neos and dans so they have also reported the hint for the presence of like sterile neutrinos but it is everything in the same direction so for the other new physics we don't have any hints so far we were able just to put some bounds so we can put some bounds on the magnitude of the non-standard interactions on the magnitude of the non-unitarity because there are no signals from what we expect we need to wait for a better resolution of the experiments and better statistics yes so any questions from the people in the hangout for instance otherwise I can we can start with some of the questions in youtube we have many here we have one from Percy Cassanus could you say one commenter is about the two events found by the experiment Anita that ice cube seems also found in the same range of energy but this is not related with neutrinos right or sorry I don't know the guy is asking that question I don't know if Percy is following something about Anita but I could not read the paper so maybe somebody else from the chat can comment on that sorry I cannot say first Percy we can explain better the question so we have another question by the first question is why the sign of delta n squared solar can be determinate with normality at the beginning and the second question is kind of why this case cannot be happening in the delta m squared atmosphere sorry I understood the first question and the second one is why the sign of the delta m squared solar can be determinate with normality so the thing is that from just from the parametrization of the oscillation of the mixing we can define either delta m2 1 always positive and then the mixing angle delta 1 2 from 0 to pi over 2 and then the other possibility is delta m 2 1 positive and negative and the delta 1 2 always smaller than pi over 4 so usually the convention is that we use delta 1 2 between 0 and pi over 2 and delta m 2 1 always positive this is just by definition delta solar neutrinos are only sensitive to the combination between of delta m delta m squared times cos to theta we are only sensitive to the sign of this combination while in the case of atmospheric neutrinos then there are some other terms in the 3-neutrino flavor effects we have really sensitivity to the delta m3 1 itself so we don't have sensitivity to delta m2 1 alone always in combination with cosinos to theta but for the delta m3 1 there is sensitivity through 3 flavor effects to the sign of the delta m3 1 ok ok anybody has a question here in Spanish or otherwise we can continue with more questioning from YouTube we have another from Brian Stevens asking about more an opinion that you can remind us do you think that what it will take new equipment to define the potential differences for sterile neutrino detection so what would be the next step to really to detect the sterile neutrino detection there are a lot of experiments looking for the sterile neutrinos there are experiments with the reactor neutrinos these neos and dance that already had some hints there are some also there is a program in Fermilab of accelerator sort baseline accelerator experiments also searching for sterile neutrinos so there are 3 experiments in the state for this accelerator program and there are many other experiments also in France in many places so I hope in several years we will have more clear result about this about sterile because on the other hand the tension with the other experiments is also there so I don't know maybe we need to understand something else is happening but so the tension is still there so let's see what happens with the new generation of experiments okay I don't know people from the handcuffs who have questions there is a guy here from the transmitting live for YouTube so anyway I have another I mean it's just if you can comment why for the two neutrinos in matters there is this difference between in the resonance for the antineutrino and neutrino when you have the two curves that one has the resonance and they let go yeah because the thing is I've seen that we have said that the the potential, the effective matter potential that neutrinos fill has different sign for neutrinos and antineutrinos then the resonance the resonance is related with the we have on the other on one hand the sign of the delta M square and on the other hand the sign of the of the potential then for neutrinos it will happen for one sign of delta M and for neutrinos for the other sign okay so more questions for Mariam I guess the okay so okay one question over here hi Mariam very very nice to hi so I would like to know what is the status of a cp violation because you went a little bit fast on those slides regarding its future I mean why do we need the dune or high pk and not a global fit for instance maybe I will share the slides so I could show you better so let me check where the slide so the thing is that with nowadays it is clear nowadays okay let me see the current and can you see it now yes so you see here in this bottom plot we have that nowadays there is a preference for value of the delta cp close to maximum close to 3 pi over 2 okay and yeah this is this is I mean it is not 3 sigma result but it is pointing to this value then in the future with for instance here NOVA the NOVA experiment you see here at the left there is the plot of the sensitivity of NOVA so in principle NOVA would be able to have a 3 sigma sensitivity on the delta cp phase but only at maximum cp violation okay if it is delta cp is close to 0 then sensitivity is lost of course but for maximum cp cp violation then NOVA alone we have 2 sigma then t2k alone t2k alone we have similar result we will have 3 sigma sensitivity of cp violation so if we combine these results together with the current results so it is very it is probable that we will get an enhanced sensitivity to delta cp phase so maybe combining everything we may have something above 3 sigma but if we want to have a sensitivity above 3 sigma coming from one only experiment okay then we need to wait to tune or hypercane only tune and half a hypercane with these very very large statistics we will be able to reach these strong sensitivities at the 5 sigma level even so the statement was for only one experiment only for one yes for sure we may have we may combine but if to have a clean measurement from only one experiment then we need to wait for this tune or hypercane okay super thank you very much okay thank you so is there any other question for mario I am going to take again a little bit in youtube no we don't have more questions from youtube so I guess if there is no other question we can okay to finish the transmission thank you very much mario it was very nice to work with you and the nice stuff that now the colloquium is going to be in our youtube channel the link that is following this is colloquium seminar colloquium series or webinar series so please if you like the channel you can subscribe follow us on twitter and all the social media that we have mario again thank you very much thank you and in two weeks we start with the season 8 of the webinar that means that we are going to have our 70th webinar so we have been in this business like for three years or more we have to check but so see you in two weeks for webinar with the low physics so see you everybody see you next time bye