G. L. Fogli, E. Lisi, A. Marrone, A. Palazzo, A. M. Rotunno
We present updated values for the mass-mixing parameters relevant to neutrino oscillations, with particular attention to emerging hints in favor of theta_13>0. We also discuss the status of absolute neutrino mass observables, and a possible approach to constrain theoretical uncertainties in neutrinoless double beta decay. Desiderata for all these issues are also briefly mentioned.
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I summarize the current state of solar neutrino research and then give my answer to the question: What should we do next?
Solar Neutrinos: Where We Are, Where We Are Going
这个演讲回答了一系列问题。为什么要研究太阳中微子？联合标准模型（太阳加电弱）对太阳中微子的预测是什么？为什么中微子通量的计算是可靠的？太阳中微子的三大问题是什么？在太阳中微子研究的前30年里，我们学到了什么？在接下来的十年里，太阳中微子物理学中最重要的可解决问题是什么？太阳中微子天体物理学中最重要的问题是什么？
A novel method to produce neutrino beams has recently been proposed : the beta-beams. This method consists in using the beta-decay of boosted radioactive nuclei to obtain an intense, collimated and pure neutrino beam. Here we propose to exploit the beta-beam concept to produce neutrino beams of low energy. We discuss the applications of such a facility as well as its importance for different domains of physics. We focus, in particular, on neutrino-nucleus interaction studies of interest for various open issues in astrophysics, nuclear and particle physics. We suggest possible sites for a low e…
Measurements of the interaction rates of the solar neutrino lines of $^7$Be and $pep$ can be used, independent of solar models, to test whether electron flavor is conserved, to determine survival probabilities of electron-type neutrinos at specific energies, and to test for the existence of sterile neutrinos. We present analytic descriptions of these tests. We also illustrate by numerical simulations, assuming matter-enhanced and vacuum neutrino oscillations, what measurements of solar neutrino lines can teach us about neutrino masses and mixing angles.
The next supernova in our galaxy will be detected by a variety of neutrino detectors. In this lecture I discuss the set of observables needed to constrain the models of supernova neutrino emission. They are the flux normalizations, and average energies, of each of the three expected components of the neutrino flux: $ν_e$, $\barν_e$, and $ν_x$ (all the other four flavors combined). I show how the existing, or soon to be operational, neutrino detectors will be able to determine the magnitude of these observables, and estimate the corresponding rates.
The detection of neutrinoless double-beta decay will establish the Majorana nature of neutrinos. In addition, if the nuclear matrix elements of this process are reliably known, the experimental lifetime will provide precious information about the absolute neutrino masses and hierarchy. I review the status of nuclear structure calculations for neutrinoless double-beta decay matrix elements, and discuss some key issues to be addressed in order to meet the demand for accurate nuclear matrix elements.
We assess how well next generation neutrinoless double beta decay and normal neutrino beta decay experiments can answer four fundamental questions. 1) If neutrinoless double beta decay searches do not detect a signal, and if the spectrum is known to be inverted hierarchy, can we conclude that neutrinos are Dirac particles? 2) If neutrinoless double beta decay searches are negative and a next generation ordinary beta decay experiment detects the neutrino mass scale, can we conclude that neutrinos are Dirac particles? 3) If neutrinoless double beta decay is observed with a large neutrino mass el…
We examine the prospects for using lead as a supernova-neutrino detector by considering the spectrum of electrons produced, and the number of one- and two-neutron events. We show that the electron energy spectrum from charged-current reactions can be used to extract information about the high-temperature component of the neutrino spectrum. Some degree of electron neutrino oscillation is expected in the supernova envelope. We examine the prospects for untangling the signatures of various oscillation scenarios, including, e.g. normal or inverted hierarchies, and different values for the small mi…
Physics potential of future measurements of atmospheric neutrinos is explored. Observation of $Δm^2_{21}$ driven sub-dominant effects and $θ_{13}$ driven large matter effects in atmospheric neutrinos can be used to study the deviation of $θ_{23}$ from maximality and its octant. Neutrino mass hierarchy can be determined extremely well due to the large matter effects. New physics can be constrained both in standard atmospheric neutrino experiments as well as in future neutrino telescopes.
The possible mechanisms of generation of the neutrino of small masses and sterile neutrino are considered. In the supposition of stability of tracks of a left-right symmetry concerning masses of constituent quarks, the angles of mixing of quarks are evaluated. With usage of experimental data on neutrino oscillation parameters the neutrino masses on order of magnitude are computed.
What Do We Know About the Tau Neutrino?
在这次演讲中，我回顾了目前的界限上的τ中微子，集中在可能性，使质量约束低于兆电子伏。
In this brief review, I discuss the new physics unveiled by neutrino oscillation experiments over the past several years, and discuss several attempts at understanding the mechanism behind neutrino masses and lepton mixing. It is fair to say that, while significant theoretical progress has been made, we are yet to construct a coherent picture that naturally explains non-zero, yet tiny, neutrino masses and the newly revealed, puzzling patterns of lepton mixing. I discuss what the challenges are, and point to the fact that more experimental input (from both neutrino and non-neutrino experiments)…
Taken at face value, current experimental data indicate the existence of a new particle, the sterile neutrino, which must be a singlet under the Standard Model gauge group. Although they are not detectable through traditional means, such particles have interesting observable consequences for particle astrophysics and cosmology. Here we examine these implications and discuss, in particular, sterile neutrino dark matter and the relationship between matter-enhanced active-sterile neutrino transformation and the synthesis of heavy elements in supernovae.
The arguments connecting detections of a reason of difficulties of a solution of a problem of a cold dark matter are adduced.
What Do Solar Models Tell Us About Solar Neutrino Experiments?
如果公布的氯和神冈太阳中微子实验的事件率是正确的，那么太阳中$^8$ B衰变产生的中微子的能谱一定不同于实验室核物理测量确定的能谱。能谱的这种变化需要超越标准电弱模型的物理学。此外，GALLEX和SAGE实验目前具有很大的统计不确定性，分别与$2 σ$和$3 σ$对标准太阳模型的预测不同。
In this talk I address the theoretical issue of what new physics is required to make $m_ν\neq 0$. I then discuss what other things may happen besides neutrino oscillations. In particular I consider a possible new scenario of leptogenesis in R parity nonconserving supersymmetry.
The possible source of the production of neutrino with large masses is considered. For this purpose the reaction nu+n to e+p+gamma, in which the electron in neW+ vertex is produced off-mass-shell, is studied.
Neutrinos from a future Galactic supernova will be detected by several large underground detectors, in particular by SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO). If, as expected, the $ν_μ$ and $ν_τ$ neutrinos have somewhat higher energy on average that the electron neutrinos, they will dominate the neutral current response. The ways to separate the neutral and charged current signals will be discussed, and the best strategy to measure the possible time delay of the neutral current events will be outlined. Given the expected count rates, one will be able to measure in this w…
What is the statistical significance of the solar neutrino flux problem?
标准太阳模型应该使用均匀随机数，而不是高斯随机数来估计输入数据中不确定性对中微子通量的影响。因此，观察到的差异可能比目前接受的要小得多。
The favoured resolution of the atmospheric neutrino anomaly involves an oscillation of the muon neutrino to a different state. Current experiments allow for the latter to contain a significantly large fraction of a non-standard flavour. We demonstrate how the next generation of experiments may take advantage of matter effects to resolve this issue.
Neutrinos are one of the major puzzles in modern physics. Despite measurements of mass differences, the Standard Model of particle physics describes them as exactly massless. Additionally, recent measurements from both particle physics experiments and cosmology indicate the existence of more than the three Standard Model species. Here we review the cosmological evidence and its possible interpretations.
Precision tests of the standard model are essential for constraining models of new physics. Neutrino-electron elastic scattering offers a clean probe into many electroweak effects that are complimentary to the more canonical measurements done at collider facilities. Such reactions are rare, even as compared with the already tiny cross-sections for neutrino-nucleon scattering, and competitive precision measurements have historically been challenging to obtain. Due to new existing and proposed high-flux neutrino sources, this is about to change. We present a topical survey of precision measureme…
Solar model predictions of 8B and p-p neutrinos agree with the experimentally-determined fluxes (including oscillations): phi(pp)_{measured} = (1.02 +- 0.02 +- 0.01)phi(pp)_{theory}, and phi(8B)_{measured} =(0.88 +- .04 +- 0.23)phi(8B)_{theory}, 1 sigma experimental and theoretical uncertainties, respectively. We use improved input data for nuclear fusion reactions, the equation of state, and the chemical composition of the Sun. The solar composition is the dominant uncertainty in calculating the 8B and CNO neutrino fluxes; the cross section for the 3He(4He, gamma)7Be reaction is the largest u…
What did we learn out of SN1987A neutrino observations? What do we still need for a full understanding? We select important issues debated in the literature on SN1987A. We focus the discussion mostly on the relevance of certain data features; on the role of detailed statistical analyses of the data; on the astrophysics of the neutrino emission process; on the effects of oscillations and of neutrino masses. We attempt to clearly identify those issues that are still open.
We investigate how the anticipated neutral current rate from $SNO$ will sharpen our understanding of the solar neutrino anomaly. Quantitative analyses are performed with representative values of this rate in the expected range of $0.8 - 1.2$. This would provide a $5 - 10 σ$ signal for $ν_e$ transition into a state containing an active neutrino component. Assuming this state to be purely active one can estimate both the $^8B$ neutrino flux and the $ν_e$ survival probability to a much higher precision than currently possible. Finally the measured value of the $NC$ rate will have profound implica…
The atmospheric neutrino anomaly is the apparent reduction of the $ν_μ/ν_{e}$ ratio observed in underground detectors. It represents either a reduction in the muon neutrino interaction rate or an excess of the electron neutrino interaction rate, or both. Unable to answer the question of ``What else could it be?'' this paper explores a number of alternatives which do not seem to be viable. Various methods to reduce the apparent muon rate or to increase the apparent electron rate are discussed. Perhaps our bias that the interactions are due to neutrinos of atmospheric origin is incorrect. Both o…
We summarize our current understanding of the neutrino flavor conversions inside a core collapse supernova, clarifying the important role played by the "collective effects" in determining flavor conversion probabilities. The potentially observable $ν_e$ and $\barν_e$ spectra may help us identify the neutrino mixing scenario, distinguish between primary flux models, and learn more about the supernova explosion.
We discuss the experimental requirements for a mass hierarchy measurement for $θ_{13}=0$ using muon neutrino disappearance. We find that a specially optimized neutrino factory at $L \simeq 6 \,000 \, \mathrm{km}$ could do this measurement using extreme luminosities. In particular, we do not require charge identification for this purpose. In order to measure the mass hierarchy for more adequate luminosities, we explore the capabilities of low energy narrow band off-axis beams, which have relatively more events at low energies. We find that, in this case, the energy resolution of the detector qu…
We consider the seesaw model with two right-handed neutrinos $N_1$ and $N_2$ which masses are hierarchical, and investigate their contribution to the neutrinoless double beta ($0 νββ$) decay. Although the lepton number is broken by the Majorana masses of right-handed neutrinos, such decay processes can be absent in some cases. We present a possibility where the lighter $N_1$ gives a destructive contribution to that of active neutrinos by choosing the specific mixing elements of $N_1$, while $N_2$ is sufficiently heavy not to contribute to the $0 νββ$ decay. In this case the mixing elements of …
The sensitivity of future neutrino oscillation experiments is determined within a frequentist framework by using a statistical procedure based on Monte Carlo simulations. I consider the search for a non-zero value of the mixing angle $θ_{13}$ at the T2K and Double-Chooz experiments, as well as the discovery of CP violation at the example of the T2HK experiment. The probability that a discovery will be made at a given confidence level is calculated as a function of the true parameter values by generating large ensembles of artificial experiments. The interpretation of the commonly used sensitiv…
I present a personal vision of what is essential in the field of neutrino mass, both from the point of view of what has been achieved and what could lie ahead. In the process, I offer a logical, theoretical and phenomenological rationale behind my opinions. It is however neither a summary of what was discussed in the conference nor a party-line viewpoint, rather an attempt to dig through the enormous body of material in our field in order to uncover a common unifying thread. The main focus is on the search for a predictive and self-contained theory of the origin and nature of neutrino mass, wi…
I recall the place of neutrinos in the electroweak theory and summarize what we know about neutrino mass and flavor change. I next review the essential characteristics expected for relic neutrinos and survey what we can say about the neutrino contribution to the dark matter of the Universe. Then I discuss the standard-model interactions of ultrahigh-energy neutrinos, paying attention to the consequences of neutrino oscillations, and illustrate a few topics of interest to neutrino observatories. I conclude with short comments on the remote possibility of detecting relic neutrinos through annihi…
This year marks the thirtieth anniversary of the only supernova from which we have detected neutrinos - SN 1987A. The twenty or so neutrinos that were detected were mined to great depth in order to determine the events that occurred in the explosion and to place limits upon all manner of neutrino properties. Since 1987 the scale and sensitivity of the detectors capable of identifying neutrinos from a Galactic supernova have grown considerably so that current generation detectors are capable of detecting of order ten thousand neutrinos for a supernova at the Galactic Center. Next generation det…
The neutrino anomalies were driving force of the developments in neutrino physics during the last 30 - 35 years. I will consider status of the anomalies after the first KamLAND result. The main questions are "What is left?" and "What is the next?" In the new phase, the phenomenological objectives of neutrino physics consist of accomplishing the program of reconstruction of the neutrino mass and flavor spectrum and searches for physics beyond the ``standard'' picture. The latter includes searches for new (sterile) neutrino states, new neutrino interactions, effects of violation of the fundament…
Searches for Dark Matter suggest that it couples to ordinary matter only very weakly and possibly only through the Higgs or other scalar bosons. On the other hand, neutrinos might not couple to the Higgs boson directly, but only through a loop of Dark Matter particles, which would naturally explain the small neutrino masses. We demonstrate that current experimental constraints on such a ``scotogenic'' scenario allow to make the linear dependence of the lightest neutrino mass on the dark sector-Higgs coupling explicit, so that a measurement by the KATRIN experiment would directly determine its …
The neutrino community is convinced that if the LMA solution is indeed correct, the prospects for next-generation, long-baseline neutrino experiments are very exciting. In this work we will argue that the prospects are not less exiting if the answer to the solar neutrino puzzle lies in the LOW region. For this purpose we explore the oscillation probabilities which are accessible to experiments which employ conventional neutrino beams. We consider the electron (anti)neutrino appearance channel, which provides information regarding not only the small $U_{e3}$-element of the leptonic mixing matri…
We calculate the fraction of B^8 solar neutrinos that arrive at the Earth as a nu_2 mass eigenstate as a function of the neutrino energy. Weighting this fraction with the B^8 neutrino energy spectrum and the energy dependence of the cross section for the charged current interaction on deuteron with a threshold on the kinetic energy of the recoil electrons of 5.5 MeV, we find that the integrated weighted fraction of nu_2's to be 91 \pm 2 % at the 95% CL. This energy weighting procedure corresponds to the charged current response of the Sudbury Neutrino Observatory (SNO). We have used SNO's curr…
Inverting the type-I seesaw formula, we reconstruct the mass matrix of the heavy right-handed neutrinos $N_i$. We analyze how the data on neutrino oscillations affect the structure of this matrix. Under the assumption of hierarchical Dirac-type neutrino masses $m_{Di}$, we compute the mixing angles among $N_i$, their masses $M_i$ and the lepton asymmetries $ε_i$ generated in their decays. Unless special cancellations take place, one finds $M_i\propto m_{Di}^2$ and the generated baryon-to-photon ratio $η_B$ is much smaller than the observed value. We show that successful baryogenesis via leptog…
This proceeding explores some of the questions that connect the LHC and neutrino experiments: What is the origin of mass? What is the meaning of flavor? Is there direct evidence of new forces or particles? The neutrino program investigating these questions is large and diverse. The strategy here, to narrow the discussion, is to focus on relatively new ideas for experiments that may be less known within the LHC community.
What Can Be Learned with an Iodine Solar-Neutrino Detector?
我们研究了碘基太阳中微子探测器的潜在好处，用于测试假设，涉及中微子振荡。我们认为，这样的探测器将有一个很好的机会区分两个允许的区域$Δm^2$ - $\sin^22θ$参数空间，如果中微子转换发生在太阳。它还应该能够检测由于真空振荡引起的信号的季节性变化，并且可能足够敏感以检测由于地球中的MSW转变引起的日/夜变化。虽然它需要校准，但在寻求实现同样目标的更雄心勃勃的项目之前，可以完成一个工作的碘检测器。
Simple rigorous quantum mechanics with no hand waving nor loopholes clarifies the confusion between three contradictory descriptions of neutrino oscillations: (1)The time oscillations shown in standard textbooks produced by neutrino eigenstates with different masses and different energies. (2) That time oscillations and interference between states having different energies cannot be observed in realistic experiments. (3) That interference between different neutrino mass eigenstates is not observable in "missing mass" experiments where information determining the neutrino mass is available from…
The possibility is considered that the verdict of the ongoing MiniBooNE neutrino experiment will favor neither of the contesting sides, stating in fact that the LSND effect with the original oscillation amplitude is not confirmed, but a new LSND effect with a considerably smaller amplitude is found (or, at least, strongly suggested). Then, in the framework of neutrino oscillations, the presence in Nature of hypothetical light sterile neutrinos (mixing with three active neutrinos with a weak strength) will be unambiguously suggested by post-MiniBooNE neutrino data (unless the credible CPT invar…
We are in the middle of a time of exciting discovery, namely that neutrinos have mass and oscillate. In order to take the next steps to understand this potential window onto what well might be the mechanism that links the quarks and leptons, we need both new neutrino beams and new detectors. The new beamlines can and should also provide new laboratories for doing charged lepton flavor physics, and the new detectors can and should also provide laboratories for doing other physics like proton decay, supernovae searches, etc. The new neutrino beams serve as milestones along the way to a muon coll…
What KM3-230213A events may tell us about the neutrino mass and dark matter
在一般$U(1)$框架下，提出KM3NeT探测到的超高能中微子源于440 PeV衰变右手中微子暗物质，通过freeze-in机制描绘满足遗迹丰度与引力波探测的参数空间，提供可检验的新物理场景。
Physics interpretation of the ``magic'' baseline, $L_{magic}$, that can play important role in future oscillation experiments is given. The ``magic'' baseline coincides with the refraction length, $l_0$. The latter, in turn, approximately equals the oscillation length in matter at high energies. Therefore at the baseline $L = l_0$ the oscillation phase is $2π$, and consequently, the ``solar'' amplitude of oscillations driven by $θ_{12}$ and $Δm^2_{21}$ vanishes. As a result, in the lowest order (i) the interference of amplitudes in the $ν_e - ν_μ$ $(ν_τ)$ transition probability is absent; (ii)…
We investigate what one can hope to learn about the parameters that describe the neutrino fluxes emitted by the explosion of a galactic supernova using the observations of a megaton-size Water-Cherenkov detector. We calculate the allowed regions that can be obtained by fitting these parameters to a simulated observation of events by such a detector. All four available detection channels (inverse beta decay, charge and neutral current on oxygen and elastic scattering on electrons) are included in the fit and we use a ten dimensional parameters space. Nine parameters describe the initial neutrin…
Neutrino oscillation data had been a big surprise to theorists, and indeed they have ongoing impact on theory. I review what the impact has been, and what measurements will have critical impact on theory in the future.
What shall we learn from a future supernova?
本文探讨了核坍缩超新星作为粒子物理与天体物理独特实验室的重要性，强调其作为全味中微子源释放引力束缚能的特性，并指出观测未来超新星及弥散超新星中微子背景的关键科学意义。
A detailed analytic and numerical study of baryogenesis through leptogenesis is performed in the framework of the standard model of electroweak interactions extended by the addition of three right-handed neutrinos, leading to the seesaw mechanism. We analyze the connection between GUT-motivated relations for the quark and lepton mass matrices and the possibility of obtaining a viable leptogenesis scenario. In particular, we analyze whether the constraints imposed by SO(10) GUTs can be compatible with all the available solar, atmospheric and reactor neutrino data and, simultaneously, be capable…
Recent discoveries in the field of neutrino oscillations have provided a unique window into physics beyond the standard model. In this lecture, I summarize how well we understand the various observations, what they tell us about the nature of new physics and what we are likely to learn as some of the planned experiments are carried out.
We perform a statistical analysis with the prospective results of future experiments on neutrino-less double beta decay, direct searches for neutrino mass (KATRIN) and cosmological observations. Realistic errors are used and the nuclear matrix element uncertainty for neutrino-less double beta decay is also taken into account. Three benchmark scenarios are introduced, corresponding to quasi-degenerate, inverse hierarchical neutrinos, and an intermediate case. We investigate to what extend these scenarios can be reconstructed. Furthermore, we check the compatibility of the scenarios with the cla…
Neutrino physics is nowadays receiving more and more attention as a possible source of information for the long--standing investigation of new physics beyond the Standard Model. The rather recent measurement of the third mixing angle $θ_{13}$ in the standard mixing oscillation scenario encourages the pursuit of what is still missing: the size of any leptonic CP violation, absolute neutrino masses and the characteristic nature of the neutrino. Several projects are currently running and they are providing impressive results. In this review, the phenomenology of neutrino oscillations that results…
We investigate the precision with which the supernova neutrino spectra can be reconstructed in water Cherenkov detectors, in particular the large scale Hyper-Kamiokande and Super-Kamiokande. To this aim, we consider quasi-thermal neutrino spectra modified by the Mikheev-Smirnov-Wolfenstein effect for the case of normal ordering. We perform three 9 degrees of freedom likelihood analyses including first inverse-beta decay only, then the combination of inverse beta decay and elastic scattering on electrons and finally a third analysis that also includes neutral scattering neutrino-oxygen events. …
We show that neutral current (NC) measurements at neutrino detectors can play a valuable role in the search for new physics. Such measurements have certain intrinsic features and advantages that can fruitfully be combined with the usual well-studied charged lepton detection channels in order to probe the presence of new interactions or new light states. In addition to the fact that NC events are immune to uncertainties in standard model neutrino mixing and mass parameters, they can have small matter effects and superior rates since all three flavours participate. We also show, as a general fea…
Recent data on neutrino mass differences are consistent with a hierarchical neutrino mass structure strikingly similar to what is observed for the other fermionic masses.
Cosmic Microwave Background (CMB) observations have been used extensively to constrain key properties of neutrinos, such as their mass. However, these inferences are typically dependent on assumptions about the cosmological model, and in particular upon the distribution function of neutrinos in the early Universe. In this paper, we aim to assess the full extent to which CMB experiments are sensitive to the shape of the neutrino distribution. We demonstrate that Planck and CMB-S4-like experiments have no prospects for detecting particular features in the distribution function. Consequently, we …
With the educated, interested non-specialist as the target audience, we overview what is known and not known about contemporary neutrino physics. Theory tells us that neutrinos are the second-most common particle in the Universe, behind only the quanta of radiation called photons. Almost a trillion neutrinos per second enter each human eyeball, and yet we do not see them; these neutrinos, in roughly equal numbers, are emanations from our Sun and relics of the hot "big bang" era of the early Universe. Much of what we know about neutrinos, and hope to learn in the future, is derived from a uniqu…
Immediately after they are born, neutron stars are characterized by an entropy per baryon of order unity and by the presence of trapped neutrinos. If the only hadrons in the star are nucleons, these effects slightly reduce the maximum mass relative to cold, catalyzed matter. However, if negatively charged particles in the form of hyperons, a kaon condensate, or quarks are also present, these effects result in an increase in the maximum mass of $\sim 0.2{\rm M}_{\odot}$ compared to that of a cold, neutrino-free star. This could lead to the delayed formation of a black hole; such a scenario is c…
A new solution to the strong CP problem with distinct experimental signatures at the LHC is proposed. It is based on the Yukawa interactions between mirror quarks, Standard Model (SM) quarks and Higgs singlets. (Mirror quarks and leptons which include non-sterile right-handed neutrinos whose Majorana masses are proportional to the electroweak scale, form the basis of the EW-$ν_R$ model.) The aforementioned Yukawa couplings can in general be complex and can contribute to $Arg\, Det M$ ($\barθ = θ_{QCD} + Arg\, Det M$) at tree-level. The crux of matter in this manuscript is the fact that {\em no…
Recent evidence for neutrino oscillations has revolutionized the study of neutrino masses and mixing. This report gives an overview of what we are learning from the neutrino oscillation experiments, the prospects for the near term, and the bright future of neutrino mass studies.
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