 Hello everybody and welcome to the Latin American Webinars of Physics. Today, I mean, welcome to, we hope that you have a very nice holidays. And we're going to restart with the webinars in this 2023. Our first speaker of this in this year is going to be Valentina de Romere. She's a postdoc in the Instituto de Física Corpuscular in Valencia, Spain. But before she had done many, many, a lot of work in different topics related with neutrinos, beyond a standard model, dark matter and neutrino physics, again. And in the past she had been, she got the PhD from the Universidad de Valencia and the Universidad de la Estudio Torino in Italy. After that she had done several postdocs in the European Network in Visibles. She has also been postdoc in the IFT in Madrid, in the WAM. Also she had done, she got the Juan de la Cerve Incorporación, a postdoc position to be done in Valencia. And lately she has researched Segi Gent from Valencia, Spain. And after that she's going to be a distinguished researcher in the CD Gent, also at the FIC. So Valentina, welcome to the Law of Physics. Please you can start your webinar and share your screen. Thank you so much, Roberto, for the introduction. Hello everyone. So let me share my screen. Can you see the presentation? Yes, perfect. Okay, so first of all I would like to thank you for this invitation. I'm really happy to participate in this Law of Physics webinar. And while in my talk today I will discuss coherent elastic neutrino nucleus scattering in the standard model and beyond. This is the outline of the talk. I will start with a brief introduction and motivations behind the coherent elastic neutrino nucleus scattering process, also called sevens. And in particular I will discuss the observation of sevens at the experiment coherent and the recent evidence for a possible observation of sevens at a reactor experiment using neutrinos from the Dresden to reactor. Then I will comment about some of the extended physics potential of sevens, both concerning standard model precision tests and the searches for new physics, for instance, in the form of new interactions in the neutrino sector. In the second part of the talk instead I would like to discuss sevens as a background for their matter searches. In this case I will comment about the impact of these recent sevens measurements on the so-called neutrino floor. And finally I will summarize. So the coherent elastic neutrino nucleus scattering process is a neutral current process in which a neutrino scatters half a nucleus by exchange of a set boson. And the neutrinos in this process sees the nucleus as a whole as a single particle. This process occurs when the momentum transferred in the process is smaller than the inverse of the nuclear radius. This means that there is an upper limit on the incoming neutrino energy of the order of about 100 MeV depending on the target material. While this makes that the nuclear amplitude sum up coherently and it leads to a cross-section announcement. So the sevens cross-section turns out to scale approximately with a number of neutrons squared and eventually this cross-section can be quite sizable. For instance, a couple of orders of magnitude larger than the inverse beta decay process which was first used to observe neutrinos. The neutrinos was first theoretically predicted in the 70s. However, it had eluded detection during more than 40 years because it is an exceptionally challenging process to observe. Indeed, despite the magnitude of its cross-section, it was not observed for so long because it gives rise to very tiny nuclear recoil energies. And so this makes the detection quite complicated. In the plot on the left, it is shown the typical magnitude of the sevens cross-section in blue compared to other neutrino cross-sections. For instance, in red, there is the inverse beta decay one. In the plot on the right instead, it is shown the typical n squared dependence of this cross-section. And also there are depicted the measurements of this cross-section by the coherent experiment which used two different targets. One is the caesium iodide first and then argon. And also there are shown some upper limits on this cross-section which have been set by other sevens experiments using reactor neutrinos. And also by their matter experiments observing astrophysical neutrinos, in particular solar neutrinos. This is really a worldwide effort in order to observe and measure this process with different experiments. And many of them are shown in this map. So I will discuss in particular about coherent, which I've said, as I've said before, it's the first one that has observed this process. And also I will comment about this experiment using neutrinos from the Dresden to reactor. As you can see from this map, basically coherent is one of the few experiments which use neutrinos from stopped pion beams. I will discuss this more in the next slide. Most of the other experiments currently running or planned in the near future instead would use neutrinos from nuclear reactors. So talking about neutrino sources for these sevens experiments, let's see which are the preferable requisites that these sources should have. So first of all, a high flux, a well understood spectrum, possibly the possible production of multiple neutrino flavors, also the possibility of locating the detector close to the source, and also a good knowledge of backgrounds in order to reject most of it. So as I was saying before, coherent uses neutrinos from PIDARS, pion decays at rest, and in particular coherent uses the spallation neutrons in which a proton hits a mercury target, and here pions are produced. The negatively charged pions are captured right away by the nuclei, whereas the positively charged ones decay at rest, producing a prompt flux of new neutrinos and delayed fluxes of electron neutrinos and muon antineutrinos. So the typical fluxes of neutrinos produced from PIDARS are shown in this figure. Most of the other sevens experiments instead uses neutrino from nuclear reactors, and in this case, the typical flux is shown in this other figure on the left. And so there are some differences among these sources. First of all, the source of neutrino from nuclear reactors produces a single flavor, because only electron antineutrinos are produced. Also, the fluxes at reactors are usually higher, and the energies are smaller, so also the recoil energies which are produced are usually even tinier, and this makes the detection at seven experiments using reactor neutrinos even more complicated. There are a few other possible neutrino sources which have been considered in the literature, however, I will not discuss them in this talk. Talking instead about detection strategies, well, you will understand right away that since these experiments need to see very tiny recoil energies, basically they have the same need like their matter data detection experiments. Also the detection strategies are therefore in common. So these experiments can use, can see for instance light, they can see photons if they rely on scintillation as a detection strategy, and this is the case for instance of the coherent experiment, or they can see ionization and this is instead for instance the case of the Dresden to reactor experiment, or they could also see phonons. This summarizes some of the experiments which have shown before on the map which are currently running, and the technology which is used for the detection, where the location and the neutrino source. So as I was saying before, coherent is one of the few that uses PIDAR neutrinos, whereas most of the others use reactor neutrinos. At the moment the only observation has been made by coherent, and there was this claim for a possible evidence of an observation also by the Dresden to reactor experiment, but I will comment more about both of them soon. Yeah, the first observation of sevens was made by this experiment coherent in 2017. So I recall here, this was done about 40 years after the first theoretical prediction, and this experiment observed sevens first using a detector made of cesium iodide. And then more recently in 2020 they repeated the detection using a different detector made of liquid argon, and in 2021 and then 2021 they also increase the statistics of the first detectors the cesium iodide one, and also they improved the data analysis. In the following I will show some results which we have obtained, analyzing this data from coherent in particular I will focus on these two data sets the liquid argon and the most recent one using cesium iodide detector. And then in the reactor neutrino experiments last year there was this claim by this experiment which was, which is actually very interesting of a possible evidence of an observation of sevens. So this experiment uses neutrino from the Dresden to reactor in the US, and the detector is a germanium detector characterized by a very low energy energy threshold. In this paper from last year, they claim this suggesting suggestive evidence of sevens, which is reported with a strong preference with respect to the background only hypothesis. However, the interpretation of these results in terms of a possible observations of sevens in the standard model is actually very strongly dependent on the quenching factor model. The quenching factor is a parameter which is very relevant because it describes the observed reduction in ionization yield produced by a nuclear recoil when compared to an electron recoil of the same energy. And this quantity is often not well known at low recoil energies. So it's a major source of uncertainty for these experiments. As you can see in this plot on the right. These, the plot shows the values for these quenching factor as a function of the nuclear recoil energy and the shaded areas are those that have been probed by these two sevens reactor experiments conus and these the Dresden to reactor neutrinos. So as you can see, there are also three different curves, let's say that correspond to three different theoretical models for these quenching factor. So within the shaded area, the differences are not so so large I mean among at least among two of them, but if we extrapolate them at very low energies we see that the expected value can be very different. So, while these, this is to make the point that indeed the quenching factor is an important source of uncertainty, and these interpretation of these experimental results in terms of an observation of sevens strongly depends on on this model. Let me now go back to the theory of sevens and in particular I would like to discuss now the sevens cross section, because this cross section is actually well calculable in the standard model. And in full generality it contains two ingredients two components, an axial one and a vector one. However, the actual contribution is in general small for most nuclei in particular the heavier ones. This is pin dependent, and therefore we can actually safely neglected. Also because the typical n square dependence which gives rise to to this typical announcement of the cross section actually comes from the vector part. So let's focus on the vector contribution to the cross section. Here the relevant ingredients are the Fermi constant a kinematics term, the nuclear for factor which includes the distributions of the nucleus inside the nucleus. And this it is approximated to one in the case of full coherence. This means when the momentum transfer goes to very small value. And then we have these weak nuclear charge, which is the quantity which eventually includes the typical n square dependence. Indeed, with the within the standard model, this is the expression for these weak charge. And we see that there is an accidental cancellation due to the value of the weak mixing angle. And that multiplies the number of protons. So it turns out that it's the neutron contribution that nominates, and this is the quantity that leads to the typical n square dependence of this cross section. The observation of sevens has really opened the window to a plethora of possibilities of physics test and probes, both concerning standard model precision test, the study of nuclear physics properties, the study of supernova and solar neutrinos, but also probes of the existence of new physics, for instance, new neutrino interactions like neutrino NSI probes of neutrino non trivial electromagnetic properties. Also, the existence of sterile neutrinos can be probed with sevens. And as we will see in the second part of the talk sevens is also a relevant background for their matter searches. So in this talk, I will try to discuss a few of a few examples among these really many, many applications of sevens. Let me start with the standard model precision test and in particular sevens can be used to determine the value of the weak mixing angle at a low energy scale. So these parameter is usually determined measured at heavier energies through collider experiments. However, sevens can can give us information about the value of these standard model parameter at lower energies. These two figures are have been taken by these references which analyze the first data set from coherent of 2017 and the liquid argon one and extracted some best fit value for this weak mixing angle, which are shown here in this plot on the right in green. This plot shows the running of the weak mixing angle as a function of the energy scale. And here we are I'm also showing the value the best fit values together with the error band that we obtained by analyzing these recent resident to reactor data. I'm showing two of them because as I said before this result depends on the quenching factor model so we chose two different theoretical models in order to see the difference. And as you can see in one of the cases, the error bar is still quite large. This other plot lower down here instead shows prospects for the determination of these parameter at the future scintillation bubble chamber experiment using a liquid argon detector and reactor neutrinos as a source. So we have updated these results for the determination of the weak mixing angle, analyzing the most recent data from coherent together with the liquid argon data set. And these results are shown here on the left in terms of these delta square and on the right again as in as a function of the running of these mix a weak mixing angle as a function of the energy scale. This is the result that we obtained from the combined analysis of the two data sets. And this is compared to the orange line, the orange curve which is the theoretical prediction because of course we can predict the value of the weak mixing angle at low scales by the RG extrapolate extrapolation. However, it is also important to confirm this experimentally, because any possible deviation from the predicted value would be a clear hint for the existence of new physics. In continuing with the standard model precision test, sevens can be used to probe the neutron density distribution. So, contrary to the proton density distributions which are better known, the neutral one is not very well known, and therefore sevens can be used to provide an independent measurement of the so-called root mean square neutron radius, which is a quantity which enters the nuclear four factor, and it is relevant therefore for the determination for the calculation of the sevens cross section. Basically, sevens can give us information about the so-called neutron skin, which is defined as the difference between the neutron and the proton radii. So also here, analyzing the two data sets of coherent from cesium iodide and liquid argon detectors, we obtained some one sigma preferred ranges for the values of these radius for the two target materials. Okay, so these were examples of possible precision test within the standard model, but actually sevens is also a very powerful tool to probe the existence of new physics beyond the standard model. And the first case that we considered are neutrino-NSI, neutrino-non-standard interactions, which are in general formulated in terms of an effective dimension six-four fermion Lagrangian of this kind. Where these epsilons are the NSI parameters, which give the strength, the magnitude of these NSI in terms of deferring, and these epsilons can be either flavor-preserving or flavor-changing. So we have analyzed, again, these coherent data, assuming the presence of, in this case, flavor-preserving NSIs, and this plot shows our results. So the lower panels correspond to the electron neutrino flavor NSI parameters, whereas the lower ones to the new one. And the plots on the left show the results for the analysis of the two data sets separately, whereas the plots on the right show the results of the combined analysis. So the first thing that we can notice is that in the case of the electron flavor, if we analyze the two data sets separately, we get one single band and not two different ones as we actually would expect. So why two? Because one of them contains the zero-zero result, which corresponds to the standard model case, and the second band corresponds to the values of the NSIs, which mimic perfectly the standard model contribution. So in the case of, when we analyze the two data sets separately, in the case of the electron flavor NSIs, we don't get these two bands because, well, the electron neutrinos are subdominant in the flux, in the neutrino flux used at coherent, and therefore, they are not enough to lift these degeneracy. However, when we combine the data sets, we get the two bands as expected. In the case of the muon flavor, instead, muon neutrinos are more sizable in the neutrino source of coherent, and therefore, we get the two bands already here. And of course, when we combine the data sets, the results, the bounds are even more stringent. Similarly, we have analyzed also the case where these NSIs are flavor changing, and now here our constraints are given in terms of one flavor changing and one flavor conserving parameter, again for the electron and the muon flavor. And as before, when we combine the data sets, the results, of course, are much more stringent. So, neutrino NSIs are actually one possibility, let's say, of these new neutrino interactions, in that case mediated by a vector particle. However, one could consider a more extended set of new interactions, which we would call neutrino generalized interactions and GI. This can include all additional types of Lorentz invariance interactions. In this case, we focus all on scalar and tensor terms. In principle, we could have also pseudo scalar or axial interactions, but as in the case of the standard model, this would lead to subdominant interactions. We decided to focus only on the scalar and tensor terms, and in this case, the effective Lagrangian for these NGI is given by this expression. So now, instead of having the excellence of the NSIs, we have these equivalent, let's say, parameters, which are called C. These NGI could be present separately, one at a time, or more than one could be present at the same time. So we perform two different analysis. In the first cases, we assume the presence of only one NGI at a time. In the second case, we assume the presence of two different NGI's. So these plots show our results from the analysis of coherent data. The upper panels correspond to the analysis of one single NGI at a time, a scalar one, a vector, or a tensor one. And while in this case, the results are given in terms of reduced chi-square profiles, again for the two data sets separately and for a combination of them. So as we can see, basically, the combined analysis is almost fully driven by the cesium iodide data set, which contains more statistics. And in the case of the vector NGI, which would correspond to the NSI case, basically, we get to minima as before we were getting the two separate bands. The lower panels instead correspond to the second analysis where we assume the presence of two different NGI's at the same time, a tensor and a scalar one, a scalar and a vector, or a tensor and a vector one. And also in this case, while the combined analysis is dominated by the cesium iodide data set and leads to quite stringent constraints in this 2D parameter space. And in this case also to the two different regions, which again correspond to the two minima for the vector NGI. Okay, so both the NGI and the NSI are effective interactions, which assume the presence of a new mediator, which is a heavier particle. However, we could consider, motivated by some theory arguments, we could consider new interactions mediated by light particles. And we could start with the light vector mediator. So in this case, our seventh cross section would be modified in this way. Now the relevant thing is that of course we have now a dependence on the mass of this mediator. We have to make some simplification, some assumptions if we want to show our results in terms of a single coupling and the mass of the mediator, because in principle, well, we have more free parameters but we are assuming that this mediator can be used equally to the quarks and to the neutrinos in a universal way. Okay, this is our assumption that allows us to show the constraints in terms in this parameter plane. The blue contour shows our 90% confidence level constraints from the combined analysis of the cesium iodide and the liquid argon coherent data. And we see that we get this weird region here, which is a region where we have a destructive interference between these new light vector mediator and the standard model contribution. I'm also showing other constraints which apply to this parameter space from other experiments, other kind of experiments or observations, and other seven experiments using reactor neutrinos like conus and coni, which have not observed yet sevens but they have published results setting some upper limits on the seventh cross section. On the right instead we show the same result the limits on on this coupling and the mass of the light vector mediator, but from the analysis of the dressing to reactor data. At very low masses the bounds are let's say almost comparable but around let's say one MV reactor data do better and the constraint is a bit more stringent than the coherent one. Similarly, we could consider also a new interaction mediated by by a light scalar particle and so in this case, our constraints are given in terms of the coupling of this scalar mediator and the mass of the scholar mediator. And also in this case we get actually in this case we get the reactor data gives leads leads to more stringent constraints compared to the coherent ones. Another BSM scenario that one can study using sevens is the so-called sterile neutrino dipole portal. And here we're assuming the possible transition of an active neutrino to a massive sterile state induced by a magnetic coupling given by this Lagrangian. So here lambda in general is a matrix a three times n matrix if we assume only one sterile state it's a three times one array basically. So we have an upper limit on the mass of the sterile state that that can be produced which is dictated by kinematics and depends on the energy of the incoming neutrinos. And the seventh cross section for this scenario gets is written here so it's a bit more complicated but it can be expressed in terms of an effective magnetic moment, which eventually encodes entries of these lambda matrix and entries of the neutrino mixing matrix. So our results are given in terms of these effective magnetic moment and the mass of the sterile state. Again I'm showing here two plots for the analysis of coherent data on the left and analysis of the dressed into reactor data on the right. Also in this case reactor data leads to lead to a bit more stringent results. However, it is interesting to notice here the complementarity between these two experiments because the reactor experiments are only sensitive to the electroneutrino flavor, whereas with coherent we can also constrain the new one. And so even if it is a bit less stringent, it provides an information that cannot be extracted using reactor data. And finally another possible BSM scenario that can be studied with sevens is that of sterile neutrino oscillations. So, as I said before, sevens is a neutral current process so it is sensitive to the total flux, the total neutrino flux so one can study the possible oscillation of the active neutrinos into sterile ones. In this case what we would observe would be a depletion in the flux, let's say, due to these oscillations. So we can perform an analysis introducing these probabilities of oscillations of active into sterile neutrinos. And in this plot I'm showing the results, the constraints that we obtained analyzing coherent data in terms of the mass splitting and the active sterile neutrino mixing angle. However, this scenario actually does not lead to a good fit of this coherent data and therefore the sensitivity to this new mass splitting and the active sterile mixing angle is still rather poor. However, it will be possibly improved with future sevens data. And now in the second part of the talk I would like to discuss sevens as a background so now until now I've shown some possibilities of what we can do using sevens data both in probing the standard model or the existence of new physics. But now in the second part I would instead like to discuss sevens as a background for the other searches. So while we all know that if the matter is in the form of particles like whims that interact among themselves and with the standard model particles then one of the strategies that has been envisaged to detect it is direct detection, which looks for the positive within a detector. In this case we are interested in the Darmader nucleus scattering. So this plot shows the current status of spin independent WIMP nucleon interactions in terms of the spin independent cross section and the WIMP mass. And as we can see there are many experiments that have already probed and constrained a large region of this parameter space. And these experiments are expected to improve furthermore in the near future by probing lower WIMP masses, thanks to lowering the energy thresholds, or also proving smaller cross sections by increasing the exposure and lowering the the So soon these experiments are expected to hit an irreducible background generated by astrophysical neutrinos. Indeed, there are some astrophysical neutrino backgrounds which will affect these direct Darmader detection experiments and so this plot shows these fluxes for these astrophysical neutrinos from the sun, the atmosphere and the diffuse supernova neutrino background. This is a cumulative flux of neutrinos produced from the core collapse explosions of supernova along the whole history of the universe. So we see that these fluxes especially at low energies the solar ones can be quite sizable. We can compute the expected recoil rates from these astrophysical neutrinos inducing sevens on the targets of these Darmader detection experiments for instance here we chose Xenon. And we see, while these are the individual recoil rates for the different neutrino sources and the total one. It is interesting to superimpose on them the expected rates from a WIMP scattering in the same target material. And we could see that a WIMP with the mass of around 60 V could mimic pretty well the expected rate from boronate solar neutrinos whereas heavier WIMP with the mass of 100 GB could mimic the expected rate from atmospheric neutrinos. So these astrophysical neutrino backgrounds will induce sevens in these detectors and produce nuclear recoil spectra, which can have a strong degeneracy with those expected from spin independent WIMP interactions. So an increase increasing the exposure of these experiments will not imply a linear improvement of sensitivities but rather will lead to a saturation of the discovery limit, which is what is typically referred to as a neutrino floor. Actually more recently people have started to talk about neutrino fog because we should not see these background as a hard limit, but well first of all it depends on several uncertainties. For sure there are astrophysical uncertainties affecting the distribution of Darmader, but there are also nuclear physics uncertainty which affect both the scattering of neutrinos and WIMPs in the detector. Uncertainties affecting the neutrino fluxes which can be quite relevant and also the possible existence of new physics in the neutrino sector. Moreover, these background can be in principle overcome for instance with measurements detailed measurements of the WIMP and neutrino recoil spectra tails or also with other techniques for instance using different target materials and so on. So what we wanted to do here was to try to use the information that we can extract from these recent seventh measurements and see how these can affect the WIMP discovery limits. So first of all, let me define a discovery limit, this is defined as the smallest WIMP cross section for which a given experiment as 90% probability of detecting a WIMP signal at at least three signals. So this is the definition that is usually considered for the determination of these WIMP discovery limits. So to obtain the discovery limit these follow usually follow a frequentist significance test using a likelihood ratio as a test statistic. And this profile likelihood ratio corresponds to a test statistic against the null hypothesis in which we assume only the sevens backgrounds from the astrophysical neutrinos versus the alternative hypothesis in which we assume the sevens background plus the WIMP signal. So we have to define a likelihood which is shown here and here the assumptions are the number of events the expected and observed ones follow a Poissonian distribution whereas the uncertainties for instance on the neutrino flux normalizations or the astrophysical uncertainties affecting the there matter distribution follow a Gaussian distribution. So this is the typical, the typical method which is followed to the to obtain these WIMP discovery limits, and we follow it the same but we wanted to extend it, including some extra uncertainties which could affect these the determination of the discovery limits. For instance, have you seen before the value of the neutron radius is still a bit uncertain. And so an uncertainty affecting this parameter could change the discovery limits. Similarly, also the value of the weak mixing angle, if we want to rely only on the value determined experimentally by the sevens experimented at a low energy scale, also is still affected by some uncertainty. However, the first analysis that we wanted to do was one that we call the data driven analysis. Here we wanted to use the measure of the sevens cross section and encodes all possible uncertainties that this cross section could involve within an uncertainty on the cross section itself. So this would be independent on any assumptions. So what we did here was to extract the value of the cross section of the sevens cross section from coherent data, together with the standard deviation. And then we waited the theoretical standard model value of the sevens cross section by a multiplicative factor that we obtained from this experimental data. This multiplicative factor is obtained as a ratio between the measured number of events over the theoretical expected ones. And these two plots shows the value of this multiplicative factor is a function of the energy beans which are given by the experimental collaborations on the left for the seismide data set and on the right for the liquid argon one. So using this information we recomputed the WIMP discovery limits and these are the results that we obtained for on the left we are assuming Xenon detector and on the right an argon one. Of course, in the case of the argon we can use the information from the liquid argon data of coherent directly. In the case of Xenon we are using the information from the seismide data set because well the mass number is very similar so we can do that. Our discovery limits are of course given in terms of the spin independent cross section and the WIMP mass and we show them for four different values of exposures. So the plain lines correspond to the standard case where we obtained these discovery limits, calculating the 7th cross section theoretically within the standard model. Whereas the dashed lines are obtained when we allow for this variation of the 7th cross section within the uncertainty that we have extracted from coherent data. So what we can see in the plot on the left is that when we use the coherent data, the seismide coherent data, we get in general an improvement of the discovery limits. Why? If we go back here we see that in this case this multiplicative factor is almost always smaller than one in almost all bins. This means that the experimentally measured 7th cross section is smaller than the theoretically predicted one. So we are, if we use the experimentally measured one, we predict less 7th events, less background and the discovery limits improve. In the case of the argon data, the situation is the opposite. Of course here the statistics is much less, so there are only three bins, but the situation is basically the opposite and that's why we have a slight worsening of the discovery limits, but the fact is much less pronounced compared to the seismide case. Okay, then another kind of analysis that we did was instead to see what was the impact of an uncertainty on the weak mixing angle value on the discovery limits. So here we allowed for a variation of this parameter within a 10% uncertainty, which is the one that we extracted from coherent data basically. And we see that the impact of this variation on the discovery limits is basically only visible here in this region, which is where the high fluxes from solar neutrinos are sizable. And the fact is that the discovery limits get slightly worsen, and this is because when this weak mixing angle value gets larger, then also this weak charge which entered 7th cross section if you remember becomes larger and therefore we are predicting more background events. And another possibility that we considered was the impact of an uncertainties on the nuclear forefactor. As I said before, the value of the neutron radius is still uncertain, so we assumed a possible variation of 10% of this parameter which enters the nuclear forefactor. And in this case, we get that actually the effect on the discovery limit is milder compared to the previous case, because actually this effect not only the 7th background but also the WIMP signals. Okay, then also another possibility that we considered was the possible presence of new physics in the neutrino sector. So as we have seen before, the possible existence for instance of a light vector mediator. So we consider this case and we see that in this case the impact is actually very large, especially at WIMP masses below 10GV or so. What we get here is that the discovery limits gets much worse. And this is because when we go to low WIMP masses or this is equivalent to go to low recoil energies, this new vector interaction is very relevant and adds on top of the standard model contribution. So we predict much more background events and therefore the discovery limits are much worse. If we go at heavier masses instead the situation gets reverted because what happens here is that basically here we would, this would correspond to heavier recoil energies. The vector contribution becomes smaller and since there can be a destructive interference because actually the weak charge of the standard model is negative and this is positive they can cancel. And that's why at heavier masses instead the discovery limits improve. Also we consider the case of possible presence of a light scalar mediator and similarly to the previous case at low WIMP masses, basically the fact is that the discovery limits get worse. And at heavier masses also these are a bit worse but I mean the fact is much less pronounced. Here it is not possible the interference because there is a chirality flip. So these new interactions cannot interfere destructively with the standard model. However, here basically the contribution from this new light scalar mediator is much smaller and that's why the fact is almost not visible on the discovery limits. So I think that with this yeah I've come to my summary. So in my talk I've discussed the coherent elastic neutrino nucleus scattering process at the beginning I introduced this process in particular highlighted the coherence condition and the typical announcement of the seventh cross section. Then I will be I have discussed some of the extended the physics potential of the sevens both concerning standard model probes and probes of new physics. I have presented some results analyzing recent data from the coherent and addressed into experiments. And in the second part of the talk instead of discuss the application of these results on their matter searches, and we have reconsidered the possible variation of the so called neutrino floor exploiting these sevens measurements by the coherent experiment. So my take home message from my talk should be that while this process is very interesting and there is a wealth of information also expected from for coming data, and these will have very relevant implications for both tests of the standard model and the approaches for new physics in the neutrino sector. If you let me one minute more, I would like to make some shameless promotion of a new project that we have just started at ify, which is a physics podcast for the general public, and it's in Spanish. So I thought that maybe among the listeners of the low physics webinar there could be some people interested. Yeah, I was saying it's a new project, which we have just started it's for outreach I mean for the general public. You can find us on all the major podcast platform so also on Twitter so if you are interested or you know someone that could be interested. Please share the words and also we counter on, we will counter I hope with the participation of many people from the low physics community because well in every episode, we have an interview for from some famous physicists so we hope to get the chance to interview also many of you. So thanks a lot I'm ready to take questions now. Thank you very much, Valentina. So, and please all the people that are following the webinar also join the, the oscillator harmonica just to also to spread the word about physics. So, thank you very much Valentina was very interesting your talk. So we are going to start with some questions we have maybe some question from the people here in the in the zoom session. I don't know if some of you guys has questions. Nicholas has one question. I have one. Thank you. Thank you very much. So I got confused with yours like 33 I think if you could please go back there. Yes. Exactly. So, yes. So, um, so the lines correspond to different so different neutrino neutrino fog background. No. Yes, these are different discovery limits. Sorry. Okay, so that's like how, how deep the, the, the vectors can go right. Exactly. Yeah. But then why the two xenon. I guess, when we have you know one ton personal to current limits. Why are they different. They are different. You mean the, the gray, the gray one. Exactly. I'm, I don't think they are different. It's different to the. Yes, the axis, the axis range. Okay, okay. Yes. I mean, this is, this is shown. I mean, of course, would apply in this case directly. I mean, it's shown more. I'm this, this limit is shown just for, for reference, let's say. Okay. But it's a different range. Yeah, y axis range probably it's that that confuses. Okay. Yes, thanks. And if I may, at the very beginning also, when you explain the question factor, the very beginning I think it's like like 10 or 11. Exactly. Yes. So use, I mean, we expect, for instance, the blue and the black, I mean, at the beginning, you want that high. Nuclear record and I just to be the same, right. So that's kind of normal. But the green one is super different. Why they were not. I mean, they will have the trick to be very, very similar. Yeah. The green one is different. Yes, that's right. I, I don't know exactly why what, what are the reasons behind I mean I know that these two ones, the blue and the black ones. I think they are extracted more experimentally and we said the green one comes from, from a theory also, I mean, it has a theory. Let's say motivation behind, but they cannot right now tell you exactly why they are so different. Because they're kind of parallel. It's just like an overall factor. Okay. So maybe the difference could be like a certain uncertainty of the model or whatever. Yeah. Okay, thanks for the question, Nicholas. Before to continue with the question from the people here in the session. I have a question from, from the YouTube channel from David Cardona. He's asking, what are the usual new clay used in this kind of experiment. I guess, also to, to see this. Then on another type if there are more new clay that can be used for this kind of For the seventh, you mean seven experiments. Yeah, like Germanium. While cesium, cesium iodide, which was used by coherent for instance, argon. These are some in general the heavier ones because since they want to to exploit this and square dependence, the heavier ones, the announcement is larger so Okay, that was the question from David. So I don't know if there are other questions from the Yes. Um, could you go to slide the 20. Yeah. Right. So, so in this, this, this fits are are very nice and there you can see the effect that you were that you were mentioning on the For example, let's let's talk about that the vector, the vector interaction. Right. So, so there you see what you see what you mentioned before right that you have the solution that That is a standard model case. And then another one that mimics the the standard models. So, so, so how does it mimic the standard model And the result in what way does it give you the same thing. Yeah, basically it modifies this week charge that I show show okay this is the new definition of the week charge in this NSI case. This is actually for the NGI. I mean, it's not with the epsilon but would be modified accordingly. And this has to be introduced here. I mean, this week charge. This was the case of the standard model. So, this is actually negative in the standard model. So if the new one, basically, cancel this and I mean gives the same amount but positive. Exactly. It mimics. Yeah. Yeah. Okay, so so can can you go back to. Yeah. Yeah, thank you so so so there there we see that. In the case where where it mimics, you have the combination of liquid argon plus CC my right to to match both of them, but not in the standard model case, right where it's zero you see you see that a that actually the fit prefers the other one so so do you have an idea why this happens. So liquid argon actually this is even more visible in the scholar and the tensor that actually the zero is not the minimum. It's not the minimum so you see, but I mean it's not significant right it's I think it's just the point is that liquid argon data are have less statistics yet I mean the data are not, let's say are not enough to really fit correctly to I mean. So the but the study as I was saying the significance that the significance of these these results is is not relevant so but in the liquid. Sure sure it's not relevant right it's a it's a very. Also for the vector indeed the zero the minimum is not exactly zero it's a bit shifted. Yeah. Right, the interesting thing is that on the other side it matches right seems to match at least I don't. Yeah, it's slightly also shifted, but probably a bit less than than the left side yes. I see. So, so nothing to to look forward to regarding. No, I guess that with the I mean actually more data from these argon detector should come so at some point and I guess with more statistics I mean everything will be back to normal I think. Okay, okay, thank you. Okay, thank you for the question. Thank you for all the David Cardona say thank you for the for the answer, and I have a couple of questions. Maybe I the details of the of the of the different measurements keep for me, but is there any possibility to to see difference in the scattering if it is neutrino anti neutrino depending on the source or the experiment just see the both type of neutrino they interact in the same way with the nuclear, or do you expect to have differences. No, in the I mean a coherence sees both of them because in the in the in the flux that is used that coherent you have both neutrinos and the muon anti neutrino. So, yes, I mean your question is more if the cross section is different or exactly. No, the cross section is, if I remember correctly, there is a minor difference, which is not because actually the cross section, which I give here gave here. Well, this contains all the kinematics kinematics terms, but some of them are subdominant. So one can consider only the relevant ones. And now the factor would be the same basically I mean and these are taken into account the coherence sees the same and the fact is this shift, I mean shift it's the recoil energy that they see the experiment can see for both neutrinos and anti neutrinos. Okay, okay. So another question that I when you were analyzing the the case of a light vector mediator. Is any implication also that you can get from fall the case of scalar and so the scalar mediator like actions major ones or I mean not the standard major one with a super weak coupling to the neutrino but maybe other type of cell the scalar particles very light cell the scalar particles. Okay, so as I was saying before the pseudo scalar in general is like the axial and leads to some leading interaction. So it's more complicated to see it. But in principle, of course, you could have a pseudo scalar mediator or an actual one. Is this what you refer to or. Yeah, yeah, because it when when you were talking about this. I thought also about this experiment that they were mentioning this. I mean, they were finding this fifth force that they know I don't remember the detail of the experiment but was a nuclear experiment in Hungary or something like that. And also they have the same when they make the analysis for the different type of mediator they take vectorial mediator and at most scale because they were saying that the scalar safety scalar and actual mediator they were too different too difficult to to try to extract. Because of the form factor and many others type of parameter and modelization that was beyond the scope of the experiment so yeah and the last question for me is the is there is other. Future experiment related with this or the interplay with friends and with June experiment or other type of nutrient experiment if they can join forces, let's say. Yeah, there are some studies of. So okay here there are many experiments which are running and some of the blue ones are expected in the future. So experiments like June in general run at higher energies, but if you go to the low energy tail then you could also observe some sevens events. So there are some people that have looked at that at the LBNF facility. Yeah, can be done but in general I mean this expiry they run they explore a different energy range so they are not really comparable in the sense that they are. As I was saying before at the beginning, you need like you have like a maximum energy on the incoming neutrino to get these coherence of the process. So you see it's around 100 MeV this depends on the target, but 100 MeV it's already like a kind of borderline I would say. So, of course, the experiments like June would be a much heavier energy so you should you can use them but only if you focus on the low energy tail. No, thanks. And one slide before I guess was the map. No, when you have the worldwide map. No, I was curious about this Violeta because he's sitting in Argentina. I don't know. It's just because of the map. I didn't know that existed. I mean that is planned. Yeah, I think yes. Cool. So let me check just if there are other questions in the social networks. So if there are other questions from the people in the, I mean, maybe Walter is going to have some questions but they are going to address it to you privately Valentina. So, so let's, I mean, we are running out of time, but we thanks again Valentina was very interesting the webinar and very, very complete. I'm sure it's going to be very helpful for many people that is going to be watching it in the old YouTube channel. And for the people that is following us, please don't forget to subscribe to the channel and social network and also don't forget to check out the YouTube channel. Thank you so much. Bye bye.