We discuss various physics aspects of neutrino oscillation with non-standard interactions (NSI). We formulate a perturbative framework by taking Δm^2_{21} / Δm^2_{31}, s_{13}, and the NSI elements ε_{αβ} (α, β= e, μ, τ) as small expansion parameters of the same order ε. Within the εperturbation theory we obtain the S matrix elements and the neutrino oscillation probability formula to second order (third order in ν_e related channels) in ε. The formula allows us to estimate size of the contribution of any particular NSI element ε_{αbeta} to the oscillation probability in arbitrary channels, and gives a global bird-eye view of the neutrino oscillation phenomena with NSI. Based on the second-order formula we discuss how all the conventional lepton mixing as well as NSI parameters can be determined. Our results shows that while θ_{13}, δ, and the NSI elements in ν_e sector can in principle be determined, complete measurement of the NSI parameters in the ν_μ- ν_τsector is not possible by the rate only analysis. The discussion for parameter determination and the analysis based on the matter perturbation theory indicate that the parameter degeneracy prevails with the NSI parameters. In addition, a new solar-atmospheric variable exchange degeneracy is found. Some general properties of neutrino oscillation with and without NSI are also illuminated.
The experimental signatures of nonstandard neutrino interactions are shown to be equivalent to CPT violation in neutrino oscillations. This result leads to a correspondence in the study of these two descriptions that can be used to constrain the relevant parameters of one formalism by using the available bounds on parameters of the other. The correspondence is illustrated and explicitly used to determine first bounds on previously unexplored parameters in both formalisms.
Muon neutrino disappearance measurements at NO$ν$A suggest that maximal $θ_{23}$ is excluded at the 2.6$σ$ CL. This is in mild tension with T2K data which prefer maximal mixing. Considering that NO$ν$A has a much longer baseline than T2K, we point out that the apparent departure from maximal mixing in NO$ν$A may be a consequence of nonstandard neutrino propagation in matter.
We show that the $R_K$ puzzle in LHCb data and the discrepancy in the anomalous magnetic moment of the muon can be simultaneously explained if a 10 MeV mass $Z^\prime$ boson couples to the muon but not the electron, and that clear evidence of the nonstandard matter interactions of neutrinos induced by this coupling may be found at DUNE.
We present a global analysis of the semileptonic and purely Leptonic nonuniversal and flavor-changing nonstandard neutrino interactions in all the known short-baseline neutrino- and antineutrino-electron scattering experiments. The nonstandard effects at the source and at the detector can be more transparent in these experiments because of the negligibly small ratio between the baselines and the neutrino energies, which is not enough for the neutrinos to oscillate, and thus can be sensitive to the new physics at the both ends. We use data from two electron-neutrino electron scattering experime…
We calculate the effect of sterile neutrinos and nonstandard neutrino interactions on the flux of active neutrinos from the Earth's crust and mantle taking matter effect into account in both cases. For simple Earth model and using previous emission flux estimates at the source, we find that for reasonable choice of parameters for both the sterile neutrino and nonstandard interaction, the effect on the neutrino flux is a few percent or less.
We consider charged Higgs and $W'$ gauge boson contributions to the quasielastic scattering $ν_τ+ n \rightarrow τ^- + p$ and $\barν_τ+ p \rightarrow τ^+ + n$ . These effects modify the standard model cross section for these processes and thus impact the extraction of the neutrino mixing angles $θ_{23}$ and $θ_{13}$ . We include form factor effects in our calculations and find the deviation of the actual mixing angle from the measured one, assuming the standard model cross section, can be significant and can depend on the energy of the neutrino.
We constrain generic nonstandard neutrino interactions with existing experimental data on neutrino transition magnetic moments and derive strong bounds on tensorial couplings of neutrinos to charged fermions. We also discuss how some of these tensorial couplings can be constrained by other experiments, e.g., on neutrino-electron and neutrino-nucleus scattering.
We study how nonstandard neutrino interactions (NSI) may be probed by a combination of coherent elastic neutrino-nucleus scattering, neutrino oscillation and collider data, from COHERENT, DUNE, T2HK and the high-luminosity (HL) LHC. We focus on NSI induced by a new flavored gauge boson $Z'$ in a generic anomaly-free ultraviolet-complete model. For $Z'$ masses above 10 GeV, the HL-LHC has the best sensitivity regardless of the flavor structure of the model. For masses between 0.01 GeV-10 GeV, current LHCb data and future COHERENT data have the best sensitivity unless the $Z'$ couplings to the f…
Coherent elastic neutrino-nucleus scattering consistent with the standard model has been observed by the COHERENT experiment. We study nonstandard neutrino interactions using the detected spectrum. For the case in which the nonstandard interactions (NSI) are induced by a vector mediator lighter than 50 MeV, we obtain constraints on the coupling of the mediator. For a heavier mediator, we find that degeneracies between the NSI parameters severely weaken the constraints. However, these degeneracies do not affect COHERENT constraints on the effective NSI parameters for matter propagation in the E…
We consider nonstandard interactions of neutrinos with electrons arising from a new light spin-1 particle with mass of tens of GeV or lower and couplings to the neutrinos and electron. This boson is not necessarily a gauge boson and is assumed to have no mixing with standard-model gauge bosons. Adopting a model-independent approach, we study constraints on the flavor-conserving and -violating couplings of the boson with the leptons from a number of experimental data. Specifically, we take into account the (anti)neutrino-electron scattering and e^+ e^- -> nu nubar gamma measurements and keep ex…
Measurements of the solar neutrino mass-squared difference from KamLAND and solar neutrino data are somewhat discrepant, perhaps due to nonstandard neutrino interactions in matter. We show that the zenith angle distribution of solar neutrinos at Hyper-Kamiokande and the energy spectrum of reactor antineutrinos at JUNO can conclusively confirm the discrepancy and detect new neutrino interactions.
We study parameter degeneracies that can occur in long-baseline neutrino appearance experiments due to nonstandard interactions (NSI) in neutrino propagation. For a single off-diagonal NSI parameter, and neutrino and antineutrino measurements at a single L/E, there exists a continuous four-fold degeneracy (related to the mass hierarchy and $θ_{23}$ octant) that renders the mass hierarchy, octant, and CP phase unknowable. Even with a combination of NO$ν$A and T2K data, which in principle can resolve the degeneracy, both NSI and the CP phase remain unconstrained because of experimental uncertain…
We analyze the energy and zenith angle distributions of the latest 2-year IceCube dataset of upward going atmospheric neutrinos to constrain sterile neutrinos at the eV scale in the 3+1 scenario. We find that the parameters favored by a combination of LSND and MiniBooNE data are excluded at more than the 99% C.L. We explore the impact of nonstandard matter interactions on this exclusion, and find that the exclusion holds for nonstandard interactions (NSI) that are within the stringent model-dependent bounds set by collider and neutrino scattering experiments. However, for large NSI parameters …
Precision measurements of leptonic mixing parameters and the determination of the neutrino mass hierarchy are the primary goals of the forthcoming medium-baseline reactor antineutrino experiments, such as JUNO and RENO-50. In this work, we investigate the impact of nonstandard neutrino interactions (NSIs) on the measurements of {sin^2 theta_{12}, Delta m^2_{21}} and {sin^2 theta_{13}, Delta m^2_{31}}, and on the sensitivity to the neutrino mass hierarchy, at the medium-baseline reactor experiments by assuming a typical experimental setup. It turns out that the true mixing parameter sin^2 theta…
We explore the impact of nonstandard interactions on neutrino propagation in accretion disks around binary neutron star mergers remnants. We show flavor evolution can be significantly modified even for values of the nonstandard couplings well below current bounds. We demonstrate the occurrence of I resonances as synchronized MSW phenomena and show that intricate conversion patterns might appear depending on the nonstandard interaction parameters. We discuss the possible implications for nucleosynthesis.
We perform a constrained spectral fit analysis of the excess observed in the electron recoil energy spectrum by XENON1T with neutrino magnetic moment, charge radius, neutrino millicharge and new light vector and scalar mediators. Within the limits allowed by other laboratory experiments we find that the excess can be explained in the range$\ (2-4)\times 10^{-11}μ_{B} $ for the magnetic moment,$\ (2-6)\times 10^{-31}$cm$^{2}$ for the charge radius, $\ (1.7-2.3)\times 10^{-12}e$ for the millicharge and $(10-100)\ $keV masses of light mediators with couplings of $ 3.5\times 10^{-7}$ for vector/ax…
We investigate the prospects for probing the strength of the possible matter nonstandard neutrino interactions (mNSI) in long baseline neutrino oscillation experiments and the interference of the leptonic CP angle $δ_{CP}$ with the constraining of the mNSI couplings. The interference is found to be strong in the case of the $ν_e \leftrightarrow ν_μ$ and $ν_e \leftrightarrow ν_τ$ transitions but not significant in the other cases. We use SPS and DUNE setups as benchmarks.
If the neutrino analogue of the Mössbauer effect, namely, recoiless emission and resonant capture of neutrinos is realized, one can study neutrino oscillations with much shorter baselines and smaller source/detector size when compared to conventional experiments. In this work, we discuss the potential of such a Mössbauer neutrino oscillation experiment to probe nonstandard neutrino properties coming from some new physics beyond the standard model. We investigate four scenarios for such new physics that modify the standard oscillation pattern. We consider the existence of a light sterile neutri…
We present a reanalysis of nonstandard neutrino-down-quark interactions of electron and tau neutrinos using solar, reactor and accelerator data. In addition updating the analysis by including new solar data from SNO phase III and Borexino, as well as new KamLAND data and solar fluxes, a key role is played in our analysis by the combination of these results with the CHARM data. The latter allows us to better constrain the axial and axial-vector electron and tau-neutrino nonstandard interaction parameters characterizing the deviations from the Standard Model predictions.
We study the matter effect caused by nonstandard neutrino interactions (NSI) in the next generation long-baseline neutrino experiments, DUNE, T2HK and T2HKK. If multiple NSI parameters are nonzero, the potential of these experiments to detect CP violation, determine the mass hierarchy and constrain NSI is severely impaired by degeneracies between the NSI parameters and by the generalized mass hierarchy degeneracy. In particular, a cancellation between leading order terms in the appearance channels when $ε_{eτ} = \cotθ_{23} ε_{eμ}$, strongly affects the sensitivities to these two NSI parameters…
New effect in neutrino spin oscillations in transversal matter currents with nonstandard interactions
Department of Physics, Branch of Lomonosov Moscow State University in Sarov（萨罗夫莫斯科国立大学物理系分校）；Department of Theoretical Physics & Department of Particle Physics and Extreme States of Matter, Faculty of Physics, Moscow State University（莫斯科国立大学物理学院理论物理系与粒子物理及极端物质状态系）
We explore the impact of nonstandard interactions at source and detector on the interpretation of reactor electron neutrino disappearance experiments with short- and medium-baseline designs. We use the constraints from the recent results from short-baseline experiments and generalize current estimates of medium-baseline event rates to include charged current interactions at source and detector with standard Lorentz structure but with nonstandard flavor structure. We find that the average spectrum of observed events at a baseline of 50 km, in the middle of the currently favored region, provides…
We explore the effects of nonstandard neutrino interactions in the lower components of the solar neutrino spectrum which are predominant by the vacuum oscillations. The recent measurements of Borexino experiment between 2011 and 2015 provide a clean test to study the nonstandard neutrino interactions at the source (sun) and the at solar detector. In this work, first the possible standard model parameters are estimated from the combined data of the low energy regime and then the nonstandard effects at the source, at the detector, and from the interplay between source and detector parameters are…
Nonstandard interactions (NSIs), possible subleading effects originating from new physics beyond the Standard Model, may affect the propagation of neutrinos and eventually contribute to measurements of neutrino oscillations. Besides this, $ μ-τ$ reflection symmetry, naturally predicted by non-Abelian discrete flavor symmetries, has been very successful in explaining the observed leptonic mixing patterns. In this work, we study the combined effect of both. We present an $S_4$ flavor model with $μ-τ$ reflection symmetry realized in both neutrino masses and NSIs. Under this formalism, we perform …
We explore the possibility of probing the nonstandard interactions between the neutrino and a hypothetical massive scalar or pseudoscalar via neutrino flavor transformation in supernovae. We find that in the ultrarelativistic limit, the effective interaction between the neutrinos vanishes if neutrinos are Dirac fermions but not if they are Majorana fermions. The impact of the new neutrino interaction upon the flavor transformation above the neutrinosphere is calculated in the context of the multi-angle "neutrino bulb model". We find that the addition of the nonstandard neutrino self-interactio…
We discuss the analytical expression of the oscillation probabilities at low energy long baseline experiments, such as T2HK and T2HKK in the presence of nonstandard interactions (NSIs). We show that these experiments are advantageous to explore the NSI parameters ($ε_D$, $ε_N$), which were suggested to be nonvanishing to account for the discrepancy between the solar neutrino and KamLAND data. We also show that, when the NSI parameters are small, parameter degeneracy in the CP phase $δ$, $ε_D$ and $ε_N$ can be resolved by combining data of the T2HK and T2HKK experiments.
We frame beta-minus decay rate perturbations in the context of charged-current (CC) nonstandard neutrino interactions (NSI). In particular, we first outline one NSI parameterization for modeling the CC NSI. Then, we demonstrate that the strength of the NSI constrained by beta-minus decay data is comparable to previously reported bounds on general CC NSI at $\mathcal{O}(10^{-4})$ to $\mathcal{O}(10^{-2})$. After discussing possible parameters involved in beta-minus decay NSI, we establish a working framework to probe potentially new physics in nuclear decay rates. Finally, we determine that cur…
Neutrino masses and the number of light neutrino species can be tested in a variety of laboratory experiments and also can be constrained by particle astrophysics and precision cosmology. A conflict between these various results could be an indication of new physics in the neutrino sector. In this paper we explore the possibility for reconciliation of otherwise discrepant results in a simple model containing a light scalar field which produces Mass Varying Neutrinos (MaVaNs). We extend previous work on MaVaNs to consider issues of neutrino clumping, the effects of additional contributions to n…
We investigate the effects of charged-current (CC) nonstandard neutrino interactions (NSIs) at the source and at the detector in the simulated data for the planned Deep Underground Neutrino Experiment (DUNE), while neglecting the neutral-current NSIs at the propagation due to the fact that several solutions have been proposed to resolve the degeneracies posed by neutral-current NSIs while no solution exists for the degeneracies due to the CC NSIs. We study the effects of CC NSIs on the simultaneous measurements of $θ_{23}$ and $δ_{CP}$ in DUNE. The analysis reveals that 3$σ$ C.L. measurement o…
Neutrino oscillation experiments in the past decades have greatly improved our knowledge on neutrinos by measuring the fundamental neutrino parameters. The ongoing and upcoming neutrino oscillation experiments are intended to pin down the neutrino mass hierarchy and to discover the leptonic CP violation. By means of neutrino oscillograms, we analyze the impact of non-standard neutrino interactions on neutrino oscillations in the Earth matter. The standard neutrino oscillation probabilities may be significantly changed by non-standard interaction parameters, and in particular, the CP-violating …
我们对非标准中微子与电子的相互作用（NSI）进行了详细的分析，包括现有加速器和反应堆中的所有μ子和电子（反）中微子数据，以及四个LEP合作项目中的"中微子计数“数据（e- e+ -> nu nu gamma）。首先，我们执行一个参数，在一个时间的分析，显示如何改善大多数约束相对于以前的文献报道的结果。我们还提出了更强大的NSI参数允许在分析中自由变化的结果。我们显示了LEP数据与其他实验相结合的重要性，以消除全局分析中的简并性，约束保存风味的NSI参数，在90%和95 % C.L.，必须位于唯一允许的区域内。尽管有这些改进的限制，仍然有很大的改进空间，对即将进行的实验构成了巨大的挑战。
We explore the implications of the Borexino experiment's real time measurements of the lowest energy part of the neutrino spectrum from the primary pp fusion process up to 0.420 MeV through the 7^Be decay at 0.862 MeV to the pep reaction at 1.44 MeV. We exploit the fact that at such low energies, the large mixing angle solution to the Mikheyev-Smirnov-Wolfenstein matter effects in the sun are small for 7^Be and pep and negligible for pp. Consequently, the neutrinos produced in the sun change their flavor almost entirely through vacuum oscillations during propagation from the sun's surface and …
New measurements of the coherent elastic neutrino-nucleus scattering (CEvNS) are expected to be achieved in the near future by using two neutrino production channels with different energy distributions: the very low energy electron antineutrinos from reactor sources and the muon and electron neutrinos from spallation neutron sources (SNS) with a relatively higher energy. Although precise measurements of this reaction would allow an improved knowledge of standard and beyond the Standard Model physics, it is important to distinguish the different new contributions to the process. We illustrate t…
Nonstandard interactions (NSI) of neutrinos with matter can significantly alter neutrino flavor evolution in supernovae with the potential to impact explosion dynamics, nucleosynthesis, and the neutrinos signal. In this paper, we explore, both numerically and analytically, the landscape of neutrino flavor transformation effects in supernovae due to NSI and find a new, heretofore unseen transformation processes can occur. These new transformations can take place with NSI strengths well below current experimental limits. Within a broad swath of NSI parameter space, we observe symmetric and stand…
We demonstrate that in the presence of (pseudo)scalar four-fermion nonstandard interactions, a homogeneous and isotropic gas of Majorana neutrinos placed in a strong magnetic field can exhibit an angular flavor instability mixing the two neutrino helicities (i.e., a `neutrino-antineutrino' instability). This instability is most pronounced for the inverted mass hierarchy and high neutrino number densities; at the same time, even a tiny transition magnetic moment of the order of $10^{-24}μ_{\text{B}}$ is quite sufficient to trigger it. We study the properties of the neutrino-antineutrino mode us…
Coherent forward scattering processes by neutrino-scalar nonstandard interactions (SNSI) induce an effective neutrino mass. In the Early Universe, a large neutrino effective mass restricts the production of neutrinos. The SNSI effect is modulated by two effective couplings, these account for the coupling between neutrinos and electrons/positrons, $G_{\rm eff}$, and the neutrino self-interaction, $G_{\rm S}$. These parameters are directly related to the effective number of relativistic species and non-zero values imply a smaller than expected $N_{\rm eff}$. We employ big bang nucleosynthesis to…
We derive the effective Hamiltonian describing collective oscillations of Majorana neutrinos with a transition magnetic moment, allowing for the presence of scalar and pseudoscalar nonstandard neutrino self-interactions (NSSIs). Using this Hamiltonian, we analyze new flavor instability channels of collective oscillations in a core-collapse supernova environment that open up in the presence of a small but nonzero neutrino magnetic moment. It turns out that, contrary to certain claims in the literature, within the minimally extended Standard Model (i.e., without NSSIs), no new instabilities aris…
The presence of nonstandard neutrino interactions (NSI) has a large effect on the precision measurements at next generation neutrino oscillation experiments. Other type of experiments are needed to constrain the NSI parameter space. We study the constraints on NSI with electrons from current and future $e^+e^-$ collider experiments including Belle II, STCF and CEPC. We find that Belle II and STCF will provide competitive and complementary bounds on electron-type NSI parameters compared to the current global analysis, and strong improvements for the constraints on tau-type NSI. In addition, CEP…
Gravitational-Wave Signatures of Nonstandard Neutrino Properties in Collapsing Stellar Cores
Academia Sinica（中央研究院）；Max-Planck-Institut für Physik（马克斯·普朗克物理研究所）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理研究所）；Fukuoka University（福冈大学）；University of Wroclaw（弗罗茨瓦夫大学）
In this work we present a scenario in which a nonstandard interaction in neutrino propagation can explain the three major tensions in the neutrino oscillation data at present. These tensions are: (i) a non-zero best-fit value of the non-standard oscillation parameters in the the global analysis of the solar and KamLAND data which rules out the standard oscillation scenario at $90\%$ C.L, (ii) the measurement of the non-maximal value of $θ_{23}$ by NO$ν$A which excludes the maximal mixing at $2.5 σ$ C.L. and (iii) a discrepancy in the $θ_{13}$ measurement by T2K which has a tension with the rea…
Neutrino non-standard interactions (NSI), previously introduced for the sun, are studied in the supernova context. For normal hierarchy the probability for electron neutrinos and antineutrinos at low energy ($E\lesssim 0.8-0.9 MeV$) is substantially increased with respect to the non-NSI case and joins its value for inverse hierarchy which is constant with energy. Also for inverse hierarchy the NSI and non-NSI probabilities are the same for each neutrino and antineutrino species. These are the possible visible effects of NSI in the supernova. The decay into antineutrinos, which has been previou…
We discuss lepton number violating processes in the context of long-baseline neutrino oscillations. We summarise and compare neutrino flavour oscillations in quantum mechanics and quantum field theory, both for standard oscillations and for those that violate lepton number. When the active neutrinos are Majorana in nature, the required helicity reversal gives a strong suppression by the neutrino mass over the energy, $(m_ν/E_ν)^{2}$. Instead, the presence of non-standard lepton number violating interactions incorporating right-handed lepton currents at production or detection alleviate the mas…
Neutrino flavour oscillation is one of the primary indication of the existence of new physics beyond standard model. The presence of small neutrino mass is indispensable to explicate the oscillation among different flavours of neutrino. By the addition of a right handed neutral lepton with the standard model fermions, it is possible to generate tiny neutrino mass. Such additional fermion may induce non-unitarity to the $3\times 3$ PMNS mixing matrix which influences the propagation of neutrino in space-time. In this work the effect of non-unitary mixing matrix is analyzed in neutrino oscillati…
Neutrino nonstandard interactions (NSI) were investigated earlier in the solar case and were shown to reduce the tensions between the data and the large mixing angle solution predictions. We extend the previous framework to the supernova and evaluate the appearance probabilities for neutrinos and antineutrinos as a function of their energy after leaving the collapsing star with and without NSI. For normal hierarchy the probability for electron neutrinos and antineutrinos at low energy ($E\lesssim 0.8-0.9 MeV$) is substantially increased with respect to the non-NSI case and joins its value for …
We study the $Δ$-resonance and deep inelastic scattering contributions in the tau-neutrino nucleon scattering $ν_τ+ N \to τ^- + X$ and $\barν_τ+ N \to τ^+ + X$ in the presence of a charged Higgs and a $W'$ gauge boson. The new physics effects to the quasielastic process have been discussed in a previous work. The extractions of the atmospheric mixing angle $θ_{23}$ rely on the standard model cross sections for $ν_τ+ N \to τ^- + X$ in $ν_τ$ appearance experiments. Corrections to the cross sections from the charged Higgs and $W'$ contributions modify the measured mixing angle. We include form fa…
We study rare decays of hyperons involving di-neutrinos in the final state in the standard model and compare them with other models. It is claimed that the branching ratio calculated in this article are 2 times the values of 331 model and exceptionally large than the previously calculated values. We explore the nonstandard neutrino interactions (NSI) and constrain NSIs free parameter with these decays. We obtain stringent bounds on of O(0.01). We show that branching ratios (Br) could be in the range of BES III if constraints are O(0.3).
