I discuss some problems connected with the high precision study of neutrino oscillations. In the general case of $n$-neutrino mixing I derive a convenient expression for transition probability in which only independent terms (and mass-squared differences) enter. For three-neutrino mixing I discuss a problem of a definition of a large (atmospheric) neutrino mass-squared difference. I comment also possibilities to reveal the character of neutrino mass spectrum in future reactor neutrino experiments.
This Comment corrects an erroneous remark by Stadnik in a recent paper to the effect that many-body neutrino-mediated forces are suppressed in all types of stars.
A number of misleading or incorrect comments by C.Giunti on seven arXiv preprints that I have written on the theory of neutrino oscillations are discussed. The essential new features of my approach are also briefly reviewed
Existing data on neutrino-electron scattering do not imply that neutrinos are not Majorana particles. The question of whether neutrinos are of Majorana or of Dirac character remains completely open.
Recently, our work regarding the definition of oscillating neutrino states in Eur. Phys. J. C 80: 68 (2020), arxiv:1902.01232 [hep-ph] has been commented upon in arXiv:2004.04739 [hep-ph]. In this note we show that, contrary to the claim in the comment, our above-mentioned work cannot be reproduced in the scheme of the so-called flavour Fock space approach described in the comment. Moreover, we prove explicitly that a flavour Fock space cannot exist in a model with massive mixed neutrinos. If the flavour Fock space scheme were viable, it would necessarily lead, as a consequence of Coleman's th…
We consider the problem of determination of the neutrino mass ordering via precise study of the vacuum neutrino oscillations in the JUNO and other future medium baseline reactor neutrino experiments. We are proposing to resolve neutrino mass ordering by determination of the neutrino oscillation parameters from analysis of the data of the reactor experiments and comparison them with the oscillation parameters obtained from analysis of the solar and KamLAND experiments.
We point out that the assumption of Lorentz noninvariance examined recently by Coleman and Glashow leads to neutrino flavor oscillations which are phenomenologically equivalent to those obtained by assuming the neutrinos violate the principle of equivalence. We then comment on the limits on Lorentz noninvariance which can be derived from solar, atmospheric, and accelerator neutrino experiments.
We briefly report on a study intended to help shape the future of neutrino physics -- an area to which Professor Gustavo Branco has made distinguished contributions.
In arXiv:2209.00561 our treatment arXiv:2208.03736 of effects of particles emitted together with neutrinos on neutrino wave packets is criticized on several grounds. We show here that this criticism is based on misinterpretation of our results and is invalid. Our conclusions and, in particular, the conclusion that neutrino wave packet separation effects are unobservable in reactor and neutrino source experiments, remain unchanged.
We discuss the implications of the time-energy uncertainty relation to recoillessly emitted and captured neutrinos (Mossbauer neutrinos) and show that it does not preclude oscillations of these neutrinos, contrary to a recent claim (J. Phys. G35 (2008) 095003, arXiv:0803.0527).
We consider the effect of thermal broadening of the $^7$Be neutrino on vacuum oscillation solutions of the solar neutrino problem and analyze the conditions under which the electron-neutrino survival probability must be averaged over neutrino energy. For "just-so" solutions with $Δm^2$ of order $5 \times 10^{-11}~{\rm eV}^2$ averaging is not necessary, but for much larger values, it is. We analyze the effective broadening due to the extended production region in the Sun and find similar results. We also comment on the possibility of seasonal variations of the $^7$Be neutrino signal.
Recently Hall, Murayama and Weiner (Phys. Rev. Lett. 84 (2000) 2572, [hep-ph/9911341]) claimed that neutrino oscillation data are well accounted for by a neutrino mass matrix which appears to have random entries. Here this claim is disputed by constructing a specific counter example. Structure in the neutrino mass matrix is clearly preferred over random matrices.
We argue that the inclusion of the flavour-changing charged currents in the analysis of the Charm II data on neutrino- electron scattering could substantially change a fit of the effective couplings and makes impossible to draw any final conclusion on the Dirac or Majorana nature of neutrinos.
The definition of `lepton flavour eigenstates' introduced in a recent paper hep-ph/0302045 is in disagreement with the Standard Model prediction for the structure of the leptonic charged current and implies the absence of neutrino oscillations following pion decay, in contradiction to experimental data
We note that the central value of the KATRIN measurement has negative mass squared, and wonder why the statistical analysis excludes such values a priori.
The ``Comment'' presented in hep-ph/0303188 is not even wrong: Fujikawa and Shrock miss entirely the crucial point that the observable quantity associated with the neutrino charge radius (NCR) is not given by the (off-shell) one-loop vertex $γ^{*}νν$ dictated by the Feynman diagrams in the $R_ξ$ gauge-fixing scheme.
I describe an attempt to understand the significance of the atmospheric neutrino deficit observed by the Kamiokande neutrino detector. In particular, I am concerned with the statistical significance quoted for the zenith-angle dependence of the deficit, which has been cited as evidence for neutrino flavor oscillations free of systematic uncertainties.
Comments related to reading the paper "Static quantities of the $W$ boson in the $SU_L(3)\times U_X(1)$ model with right-handed neutrinos", hep-ph/0312308 (by J. L. Garcia-Luna et al) are given. They do not concern the main results of the paper but a statement there about the Higgs sector of the 331 model with right-handed neutrinos. The scalar sextet introduced here may help us to generate neutrino masses in an acceptable range.
We point out some serious mistakes in the investigation of Zhukovskii et al. Both the amplitude and the probability of the process were calculated wrongly, that is, the problem of the neutrino pair production by a virtual photon in an external magnetic field is still unsolved.
We comment on the paper ``Remarks on flavor-neutrino propagators and oscillation formulae'' [Phys. Rev. D64, 013011 (2001)]. We show that the conclusions presented in that paper do not apply to the exact field theoretical oscillation formulae obtained in the BV formalism (for three flavors) which are free from the dependence on arbitrary mass parameters, account for CP violation and reduce to the usual quantum mechanical (Pontecorvo) three flavor oscillation formulae in the relativistic limit.
We investigate the implications of a possible excess of the electron neutrino events in the Super-Kamiokande atmospheric neutrino experiment. The excess, if real, leads to constraints on the $ν_μ\leftrightarrow ν_e$, $ν_μ\leftrightarrow ν_τ$ and $ν_e \leftrightarrow ν_τ$ oscillation parameters. Specifically, the excess impies that $ν_e - ν_μ$ and $ν_μ- ν_τ$ mixings are large and $ν_e - ν_τ$ mixing is small. We show that the electron neutrino excess favors the large mixing angle MSW solution of the solar neutrino problem.
D. Borah and B. Karmakar in Phys. Lett. B789 (2019) have proposed an A4 flavoured linear seesaw model to realise light Dirac neutrinos. In this comment article, we show that some neutrino Yukawa interactions were missed in the model, thus implying that a different formula would be needed to determine the effective neutrino mass matrix, with significantly different results. Our result shows that, unlike stated in Phys. Lett. B789 (2019), that the inverted neutrino mass spectrum is not ruled out.
Comment on "Neutrino oscillations originate from virtual excitation of $Z$ bosons" and "Neutrinos produced from $β$ decays of neutrons cannot be in coherent superpositions of different mass eigenstates"
A mechanism of radiatively generating neutrino masses is implemented in an SU(2)_L x U(1)_Y x SU(2)'_L x U(1)'_Y model, where the first and second families respect SU(2)_L x U(1)_Y while SU(2)'_L x U(1)'_Y is specific for the third family. The fourth neutrino, nu_s, that has a U(1)_Y x U(1)'_Y coupling joins in the model to induce neutrino mixings by additional interactions with e and mu. The phenomenologically consistent oscillation of nu_s - nu_e requires a dominated coupling of nu_s to e.
It has been suggested that the temporal oscillations in the rate of decay of Pr ions reported in the GSI K-capture experiment arise from interference between different values of the momentum of the Pr ions. It is shown here that any such interference cannot contribute to the decay rate of those ions.
As pointed out previously, some of the hypotheses used in the standard discussion of the quantum mechanics neutrino oscillations, recently summarised in the paper `Theory of Neutrino Oscillations' by C.Giunti, lack any physical foundation and lead to neglect of both a factor of two correction in the contribution of neutrino propagation to the oscillation phase and an important contribution to the latter from the propagator of the source particle.
We show that a criticism made in hep-ph/0610294 against our paper Mod. Phys. Lett. A21, 1769 (2006) has no ground. We confirm that all results of investigations of the so-called ``spin light of neutrino (SL ν)'' are incorrect because of the medium influence on photon dispersion. With taking account of this influence, both the SL νradiation rate and the total power are zero for neutrinos in all real astrophysical conditions.
We point out three apparent inconsistencies in the treatment of oscillation coherence from reactor neutrino and source neutrino experiments in recent paper "Damping of neutrino oscillations, decoherence and the lengths of neutrino wave packets''. First, that the dependence of the oscillation probability upon the subsequent interactions of entangled recoil particles implies causality violations and in some situations superluminal signaling; second, that integrating over a non-orthogonal basis for the entangled recoil leads to unphysical effects; and third, that the question of what interactions…
We discuss the physics potential of future tritium beta-decay experiments having a sensitivity to a neutrino mass ~\sqrt{|Δm^{2}_{23}|}~5x10^{-2} eV. The case of three-neutrino mixing is analised. A negative result of such an experiment would imply that the neutrino mass spectrum is of normal hierarchical type. The interpretation of a positive result would depend on the value of the lightest neutrino mass; if the lightest neutrino mass satisfies the inequality min(m_j) << \sqrt{|Δm^{2}_{23}|}, it would imply that the neutrino mass spectrum is of the inverted hierarchical type.
We show in a simple and general way that matter effects do not contribute to the averaged value of the probabilities of transition of solar $ν_e$'s into other states in the case of maximal mixing of any number of massive neutrinos. We also show that future solar neutrino experiments (Super-Kamiokande and SNO) will allow to test the model with maximal mixing of three massive neutrinos in a way that does not depend on the initial solar neutrino flux.
We present one point of contact between the standard theory of neutrino oscillations and the alternative one, in which flavor neutrinos are described by states with definite masses. We show that both theories give the same results for static neutrinos only.
It is shown that we cannot put Majorana neutrinos in the standard Dirac theory without violation of the gauge invariance. Experiments on $ν_l \to l (l = e, μ, τ)$ transitions do not confirm this supposition. It means that on neutrino oscillation experiments, the Majorana neutrino oscillations cannot be observed.
Using the family symmetry, in the neutrino mass matrix we remove the Yukawa coupling (arising in the Dirac type mass between the heavy neutrinos and light lepton doublets) dependence in the double seesaw mechanism so that it is directly proportional to the mass matrix $m^{(nn)}$ of heavy Majorana neutrinos. The family symmetry is supposed to be broken spontaneously at high energy scale so that the neutrino mass matrix is given by the family symmetry at high energy scale. With the permutation symmetry $S_3$, we note a variety of possible mass hierarchies arising distinctly in neutrinos, charged…
Several authors have pointed out that the scalar-mediated interaction of neutrinos in a neutriophilic two-Higgs-doublet model (nu2HDM) can be as strong as electromagnetic interaction [1-3]. We show that the coupling constants of neutrino-scalar interaction are actually restricted to be y_i < 1.5 x 10^{-3} by supernova neutrino observation, and further constrained to be y_i < 2.3 x 10^{-4} by precision measurements of acoustic peaks of the cosmic microwave background. Based on the energy-loss argument for supernova cores, we derive a slightly more restrictive bound y_i < 3.5 x 10^{-5}. Therefor…
In the Standard theory of neutrino oscillations it is supposed that physical observed neutrino states $ν_{e}, ν_μ, ν_τ$ have no definite masses and that neutrinos are initially created as mixture of $ν_{1}, ν_{2}, ν_{3}$ neutrino states and that neutrino oscillations are the real ones even when neutrino masses are different. It is shown that these suppositions lead to violation of the law of energy and momentum conservation and then the neutrino states are unstable ones and they must disintegrate. Then the development of the standard theory of neutrino oscillations in the framework of particle…
We revisit the calculation of the three-loop diagrams for the radiative neutrino mass generation and consider some relevant constraints on the model recently proposed by L. Jin {\it et al} [Phys. Lett. B 741 (2015) 163]. We find that the previous approximation is inappropriate due to the neglect of some important contributions, and the benchmark point proposed can neither give rise to enough neutrino masses nor accommodate these additional constraints, such as the validity of the perturbation theory, the electroweak precision measurements, and the neutrinoless double beta decays.
It has been recently suggested in hep-ph/9911535 and hep-ph/0006324 that the fourth generation of leptons and quarks is not excluded by the precision Z-boson measurements, provided that the mass of the fourth neutrino is around 50 GeV and that its mixing with the neutrinos of the first three generations is negligibly small. We would like to note that in this case the decay rate of the Standard Model Higgs boson into the pair of such neutrinos would be about two orders of magnitude higher than than the Higgs to b-bbar rate. Thus, the predominant decay mode of the Higgs would be invisible, which…
We comment on a recent article by Yoo et al. that presents an analysis of Super-Kamiokande 10-day and 5-day data, correcting certain errors in that article. We also point out that, in using the Lomb-Scargle method of power spectrum analysis, Yoo et al. ignore much of the relevant data. A likelihood analysis, that can take account of all of the relevant data, yields evidence indicative of modulation by solar processes.
In the standard theory of neutrino oscillations it is supposed that physical observed neutrino states $ν_{e}, ν_μ, ν_τ$ have no definite masses, that they are initially produced as a mixture of the $ν_{1}, ν_{2}, ν_{3}$ neutrino states (are produced as a wave packet), and that neutrino oscillations are the real ones. Then this wave packet must decompose at a definite distance into constituent parts and neutrino oscillations must disappear. It was shown that these suppositions lead to violation of the law of energy and momentum conservation. An alternative scheme of neutrino oscillations obtain…
We review the current status of the solar neutrino oscillation parameters. We discuss the conditions under which measurements from future solar neutrino experiments would determine the oscillation parameters precisely. Finally we expound the potential of long baseline reactor anti-neutrino experiments in measuring the solar neutrino oscillation parameters.
An analysis of 3-flavour neutrino oscillations inside the Earth is presented in terms of the oscillograms -- contour plots of oscillation probabilities in the plane neutrino energy -- nadir angle. Special attention is paid to CP violation in neutrino oscillations in the Earth.
A brief review of the problem of neutrino masses and oscillations is given. In the beginning we present an early history of neutrino masses, mixing and oscillations. Then we discuss all possibilities of neutrino masses and mixing (neutrino mass terms). The phenomenology of neutrino oscillations in vacuum is considered in some details. We present also the neutrino oscillation data and the seesaw mechanism of the neutrino mass generation.
The three neutrino mass matrices in the $SU(5)\times U(2)$ model are studied focusing on the neutrino oscillation experiments. The atmospheric neutrino anomaly could be explained by the large $ν_μ - ν_τ$ oscillation. The long baseline experiments are expected to detect signatures of the neutrino oscillation even if the atmospheric neutrino anomaly is not due to the neutrino oscillation. However, the model cannot solve the solar neutrino deficit while it could be reconciled with the LSND data.
In the Standard theory of neutrino oscillations is used scheme of mass mixings, i.e., oscillation parameters are expressed via terms of mass matrix. In this work neutrino oscillations generated by charge (the weak interaction couple constants) mixings are considered. Expressions for angle mixings and lengths of oscillations are obtained. The expressions of the probability for three neutrino oscillations are given. Neutrino oscillations in this scheme (mechanism) are virtual if neutrino masses are not equal and real if neutrino masses are equal.
It is shown that in the two schemes with four massive neutrinos which are compatible with the results of all neutrino oscillation experiments, the probabilities of nu_e disappearance and nu_mu->nu_e appearance in long-baseline experiments are severely constrained.
Recently, in ref. \cite{A4Datta} Datta et al. [arXiv:2106.06773] proposed an $A_4$ flavor symmetric model supplemented by $Z_2\times Z_3$ symmetry which can accommodate the appropriate lepton mixing and neutrino masses via Type-I seesaw mechanism. They have constructed a minimal model with only one $SU(2)_L$ doublet scalar and six flavons that generate a specific flavor structure, favors the normal hierarchy of light neutrinos and narrows down the range of Dirac CP violating phase. Taking into account the contribution of all invariant terms, under all symmetries, is very important in the model…
Neutrino mixing and basics of neutrino oscillations are considered. Recent evidences in favour of neutrino oscillations, obtained in the solar and atmospheric neutrino experiments, are discussed. Neutrino oscillations in the solar and atmospheric ranges of $Δm^{2}$ are considered in the framework of the minimal scheme with the mixing of three massive neutrinos.
This brief report is an extension of a prediction of neutrino oscillation with a sterile neutrino using parameters of the sterile neutrino mass and mixing angle recently extracted from experiment.
This is an extension of estimates of the probability of $ν$ to $e$ neutrino oscillation with one sterile neutrino to three sterile neutrinos, using a 6x6 matrix. Since the mixing angle for only one sterile neutrino has been experimentally determined, we estimate the $ν$ to $e$ neutrino oscillation probability with different mixing angles for two of the sterile neutrinos.
After some generalities on neutrino oscillations and on neutrinos, the recent experimental results presented by Soudan 2, MACRO and SuperKamiokande at the Neutrino'98 conference are summarized and discussed.
We explain the physics of neutrino oscillation in vacuum and in matter. We attempt to clarify several features of oscillation that can be puzzling when neutrinos are their own antiparticles.
Recently neutrino oscillation experiments have shown that it is very likely that there are one or two sterile neutrinos. In this review neutrino oscillations with one, two, three sterile and three active neutrinos, and parameters that are consistent with experiments, are reviewed.
Recent Super-Kamiokande data on the atmospheric neutrino anomaly are used to test various mechanisms for neutrino oscillations. It is found that the current atmospheric neutrino data alone cannot rule out any particular mechanism. Future long-baseline experiments should play an important role in identifying the underlying neutrino oscillation mechanism.
