Neutrino Oscillations Research Articles

Phenomenology of (3+1) Four Flavour Neutrino Oscillations in Dense Matter

The mass square difference varies as neutrinos interact with the matter, assuming four flavours of neutrino oscillations. Three regions – vacuum-dominated, resonance-dominated, and matter-dominated – are where the neutrinos oscillate. This research goes on to examine how each of these three locations affects the likelihood of neutrino oscillations and the mass square difference in distinct ways. There are three alternative analytical formulas for the mass square difference. In this study, we have studied the behaviour of neutrino oscillations for four flavours in vacuum-dominated, resonance-dominated, and matter-dominated regions.

Decays Z → eaeb in a 3-3-1 model with neutral leptons

Abstract We investigate the 3-3-1 model with neutral leptons, a specific extension of the 3-3-1 models that includes heavy neutral leptons, which are sufficient to accommodate the neutrino oscillation data via the inverse seesaw mechanism. We will point out that this model can simultaneously explain the lepton flavor violating decays of the Z and Standard Model-like Higgs bosons into different charged leptons Z, h → e a e b , as well as the charged lepton decays e b → e a γ, in agreement with the recent experimental data. In addition, the numerical results show strong correlations among the decay rates of the Z and h bosons predicted by this model. Specifically, some of these rates are nearly linearly dependent on each other. Consequently, the decay channels can be theoretically determined if one of them is detected in experiments.

Neutrino oscillation in the presence of background classical sources

Abstract The presence of background classical sources affects a quantum field theory significantly in different ways. Neutrino oscillation is a phenomenon that confirms that neutrinos are massive fermions in nature, a celebrated result in modern physics. Neutrino oscillation plays an important role in many astrophysical observations. However, the interactions between the background classical sources with neutrinos are not often considered. In the present article, we show the effect of some classical sources, namely matter currents, electromagnetic waves, torsion, and gravitational waves on neutrino oscillation. It is shown explicitly that the above sources can change the helicity state of neutrinos during neutrino oscillation.

Neutrino many-body correlations

This paper responds to suggestions that the standard approach to collective neutrino oscillations leaves out potentially important quantum many-body correlations. Arguments in favor of this idea have been based on calculations that, on close scrutiny, offer no evidence either way. Inadequacies of the usual quantum-kinetic formalism are not currently supported by the literature.

Muonic force and nonstandard neutrino interactions at muon colliders

The discovery of neutrino oscillations implies that neutrinos are massive and mixed, necessitating an extension of the Standard Model, which may require the introduction of nonstandard neutrino interactions (NSIs). We investigate the potential of a high-energy muon collider to probe such NSIs with muons, specifically focusing on muonic forces. By analyzing the monophoton signal from the process μ+μ−→νν¯γ, we explore four-fermion contact interactions involving two muons and two neutrinos. Moreover, we examine minimal models that generate scalar and vector-mediated NSIs and study their phenomenology. Projected sensitivities for the strength of NSIs, εαβμμ, are presented at a 95% confidence level for a center-of-mass energy of 3 TeV and integrated luminosities of L=1 and 10 ab−1, showcasing the complementarity between a muon collider and other experimental probes. Published by the American Physical Society 2024

Muon g−2 and lepton flavor violation in supersymmetric GUTs

We present a class of supersymmetric (SUSY) GUT models that can explain the apparent discrepancy between the SM predictions and experimental values of muon g−2 while providing testable signals for lepton flavor violation in charged lepton decays. Moreover, these models predict LSP neutralino abundance that is compatible with the Planck dark matter bounds. We find that scenarios in the framework of SU(4)c×SU(2)L×SU(2)R unification, with additional symmetries to explain fermion masses and neutrino oscillations, provide interesting benchmarks for the search of SUSY by correlating a possible manifestation of it in dark matter, rare lepton decays, and LHC signals. Published by the American Physical Society 2024

A4×Z2×Z4 flavor symmetry model for neutrino oscillation phenomenology

We propose a SM extension which aims to explain the most recent experimental data on neutrino oscillation. Beside $A_4$, two Abelian symmetries $Z_2$ and $Z_4$ are supplemented to prevent some Yukawa terms to get the desired mass matrices and then give predictions for the neutrino oscillation parameters in agreement with the most recent experimental data on neutrino oscillation in 3$\sigma$ range. The model provide a predictive relation between the solar and reactor neutrino mixing angles and gives possible prediction on the Dirac CP phase and two Majorana phases as well as the effective neutrino mass being in agreement with the most recent constraints.

Understanding gravitationally induced decoherence parameters in neutrino oscillations using a microscopic quantum mechanical model

In this work, a microscopic quantum mechanical model for gravitationally induced decoherence introduced by Blencowe and Xu is investigated in the context of neutrino oscillations. The focus is on the comparison with existing phenomenological models and the physical interpretation of the decoherence parameters in such models. The results show that for neutrino oscillations in vacuum gravitationally induced decoherence can be matched with phenomenological models with decoherence parameters of the form Γ ij ∼ Δ m 4 ij E -2. When matter effects are included, the decoherence parameters exhibit a dependence on the varying matter density across the Earth layers. This behavior can be explained by the nature of the coupling between neutrinos and the gravitational wave environment, as suggested by linearised gravity. On a theoretical level, these different models can be characterised by a different choice of Lindblad operators, with the model with decoherence parameters that do not include matter effects being less suitable from the point of view of linearised gravity. Consequently, in the case of neutrino oscillations in matter, the microscopic model does not agree with many existing phenomenological models that assume constant decoherence parameters in matter. Nonetheless, we identify the KamLAND experimental setup as particularly well-suited to establish the first experimental constraints on the model parameters, namely the neutrino coupling to the gravitational wave environment and its temperature, based on a prior analysis using the phenomenological model.

Realism-based nonlocality in neutrino oscillations

Realism-based nonlocality in neutrino oscillations

Relic abundance of dark matter with [formula omitted](54) flavor symmetry

In this work we discuss the neutrino phenomenology in a Δ(54) discrete flavor symmetry and evaluate the relic abundance of dark matter (DM) and active neutrino-DM mixing angle considering various cosmological constraints. We introduced two Standard Model Higgs particles along with vector-like fermions and a new particle (S) which is a gauge singlet in the Standard Model. This modification leads to a mass matrix that diverges from the tribimaximal neutrino mixing pattern resulting in a non-zero reactor angle (θ13). We also incorporated a Z2⊗Z3⊗Z4 symmetry for the specific interactions in our model. The additional particle S is a sterile neutrino which is considered to be a probable dark matter candidate with mass in keV range.

Two Texture Zeros for Dirac Neutrinos in a Diagonal charged lepton basis

Abstract A systematic study of the neutrino mass matrix Mν with two texture zeros in a basis where the charged leptons are diagonal, and under the assumption that neutrinos are Dirac particles, is carried through in detail. Our study is done without any approximation, first analytically and then numerically. Current neutrino oscillation data are used in our analysis. Phenomenological implications of Mν on the lepton CP violation and neutrino mass spectrum are explored.Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

Gravitational effects on quantum correlations in three-flavor neutrino oscillations

In this paper, we explore the quantum properties of three-flavor neutrino propagating in a Schwarzschild metric. It is found that the different strength of gravitational effects are obtained by adjusting the magnitude of GM\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathrm GM$$\\end{document} arising in the oscillation phase. Using the weak field approximations, we show that the gravitational effects can make the entanglement oscillates over a large rage when GM=5.1×108Km\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{GM}=5.1\ imes 10^8 \\, \ extrm{Km}$$\\end{document} and GM=7×107Km\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{GM}=7\ imes 10^7 \\, \ extrm{Km}$$\\end{document}, respectively, Moreover, for GM=4.8×108Km\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{GM}=4.8\ imes 10^8 \\, \ extrm{Km}$$\\end{document} and GM=9.3×107Km\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{GM}=9.3\ imes 10^7 \\, \ extrm{Km}$$\\end{document}, the suppression of the entanglement can be observed due to the gravitational effects. Meanwhile, in this case, the gravitational effects also make the distribution of entanglement tighter through investing the entanglement complete monogamy relation. Furthermore, we examine the gravitational effects on the violation of the Svetlichny inequality to study the nonlocality of the system. It is shown that when GM=6×108Km\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{GM}=6\ imes 10^8 \\, \ extrm{Km}$$\\end{document} and GM=7×107Km\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{GM}=7\ imes 10^7 \\, \ extrm{Km}$$\\end{document}, the gravitational effects make the Svetlichny parameters always greater than 4, implying that the genuine tripartite nonlocality of the system is always present. However, the gravitational effects also restrain the violation of the Svetlichny to make the regions of the absence of nonlocality increase. The gravitational effects on the monogamy property of nonlocality lies in the change of the effective bound of the maximum bipartite nonlocality of the neutrinos system. Therefore, our investigations may be helpful to understanding of quantumness of the neutrinos system in curved space-time.

Measurement of neutrino oscillation parameters with the first six detection units of KM3NeT/ORCA

KM3NeT/ORCA is a water Cherenkov neutrino detector under construction and anchored at the bottom of the Mediterranean Sea. The detector is designed to study oscillations of atmospheric neutrinos and determine the neutrino mass ordering. This paper focuses on an initial configuration of ORCA, referred to as ORCA6, which comprises six out of the foreseen 115 detection units of photo-sensors. A high-purity neutrino sample was extracted, corresponding to an exposure of 433 kton-years. The sample of 5828 neutrino candidates is analysed following a binned log-likelihood method in the reconstructed energy and cosine of the zenith angle. The atmospheric oscillation parameters are measured to be sin2θ23=0.51−0.05+0.04\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\sin}^2{\ heta}_{23}={0.51}_{-0.05}^{+0.04} $$\\end{document}, and Δm312=2.18−0.35+0.25×10−3eV2∪−2.25−1.76×10−3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\Delta {m}_{31}^2={2.18}_{-0.35}^{+0.25}\ imes {10}^{-3}{\ extrm{eV}}^2\\cup \\left\\{-2.25,-1.76\\right\\}\ imes {10}^{-3} $$\\end{document} eV2 at 68% CL. The inverted neutrino mass ordering hypothesis is disfavoured with a p-value of 0.25.

Complete study of RG evolution induced leptogenesis in flavor symmetry scenarios

In the literature, motivated by the observed peculiar neutrino mixing pattern and a preliminary experimental hint for maximal Dirac CP phase (i.e., δ∼3π/2), a lot of flavor and CP symmetries have been proposed to help us understand and explain these experimental results. However, for some flavor-symmetry scenarios (see section motivations of our study), the leptogenesis mechanism is prohibited from working as usual. To tackle this problem, in this paper we have made an exhaustive study of the possibility that the renormalization group evolution effect may induce a successful leptogenesis for these particular scenarios. Our study provides complementarities to the previous related studies in Xing and Zhang, []; Xing and Zhang, []; and Cooper , [] (see section complementarities of our study to previous related studies). Published by the American Physical Society 2024

Impacts of Black-hole-forming Supernova Explosions on the Diffuse Neutrino Background

The flux spectrum, event rate, and experimental sensitivity are investigated for the diffuse supernova (SN) neutrino background (DSNB), which originates from past stellar collapses and is also known as a supernova relic neutrino background. For this purpose, the contribution of collapses that lead to successful supernova explosion and black hole (BH) formation simultaneously, which are suggested to be a nonnegligible population from the perspective of Galactic chemical evolution, is taken into account. If the BH-forming SNe involve matter fallback onto the protoneutron star for the long term, their total emitted neutrino energy becomes much larger than that of ordinary SNe and failed SNe (BH formation without explosion). Then, in the case of the normal mass hierarchy in neutrino oscillations and with half of all core-collapse SNe being BH-forming SNe, the expected event rate according to the current DSNB model is enhanced by up to a factor of 2 due to the BH-forming SNe. While substantial uncertainties exist regarding the duration of the matter fallback, which determines the total amount of emitted neutrinos, and the fraction of BH-forming SNe, the operation time required to detect the DSNB at Hyper-Kamiokande would be reduced by such contribution in any case.

Constraining dark matter from strong phase transitions in a U1Lμ−Lτ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ extrm{U}{(1)}_{L_{\\mu }-{L}_{\ au }} $$\\end{document} model: implications for neutrino masses and muon g − 2

In this paper, we study a non-minimal gauged U1Lμ−Lτ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ extrm{U}{(1)}_{L_{\\mu }-{L}_{\ au }} $$\\end{document} model, where we add two complex singlet scalars, three right-handed Majorana neutrinos (RHN), and a vector-like dark fermion to the Standard Model (SM), all non-trivially charged under the extra gauge symmetry. The model offers an easy resolution to the muon (g – 2) anomaly, which fixes the scale of spontaneous symmetry breaking. Furthermore, the two-zero minor structure in the RHN mass matrix provides successful predictions for neutrino oscillation parameters, including the Dirac phase. The extended scalar sector can easily induce first-order phase transitions. We identify all possible phase transition patterns in the three-dimensional field space. We quantify the associated gravitational waves from the sound wave source and demonstrate that the signatures can be observed in future space-based experiments. We find that strong first-order phase transitions require large values of scalar quartic couplings which constrain the scalar dark matter (DM) relic density to a maximum of 10−2 and 10−5 when we consider the DM direct detection bound. Nonetheless, the model successfully explains the DM relic density via contribution from the vector-like dark fermion. We show the allowed range of the model parameters that can address all the beyond SM issues targeted in this study.

Exploring atmospheric neutrino oscillations at ESSnuSB

This study provides an analysis of atmospheric neutrino oscillations at the ESSnuSB far detector facility. The prospects of the two cylindrical Water Cherenkov detectors with a total fiducial mass of 540 kt are investigated over 10 years of data taking in the standard three-flavor oscillation scenario. We present the confidence intervals for the determination of mass ordering, θ23 octant as well as for the precisions on sin2θ23 and Δm312\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\left|\\Delta {m}_{31}^2\\right| $$\\end{document}. It is shown that mass ordering can be resolved by 3σ CL (5σ CL) after 4 years (10 years) regardless of the true neutrino mass ordering. Correspondingly, the wrong θ23 octant could be excluded by 3σ CL after 4 years (8 years) in the case where the true neutrino mass ordering is normal ordering (inverted ordering). The results presented in this work are complementary to the accelerator neutrino program in the ESSnuSB project.

Leptogenesis in SO(10) with minimal Yukawa sector

In prior studies, a very minimal Yukawa sector within the SO(10) Grand Unified Theory framework has been identified, comprising of Higgs fields belonging to a real 10H, a real 120H, and a 126¯H\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\overline{126}}_H $$\\end{document} dimensional representations. In this work, within this minimal framework, we have obtained fits to fermion masses and mixings while successfully reproducing the cosmological baryon asymmetry via leptogenesis. The right-handed neutrino (Ni) mass spectrum obtained from the fit is strongly hierarchical, suggesting that B − L asymmetry is dominantly produced from N2 dynamics while N1 is responsible for erasing the excess asymmetry. With this rather constrained Yukawa sector, fits are obtained both for normal and inverted ordered neutrino mass spectra, consistent with leptonic CP-violating phase δCP indicated by global fits of neutrino oscillation data, while also satisfying the current limits from neutrinoless double beta decay experiments. In particular, the leptonic CP-violating phase has a preference to be in the range δCP ≃ (230 – 300)°. We also show the consistency of the framework with gauge coupling unification and proton lifetime limits.

Violation of LGtI inequalities in the light of NOν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ u $$\\end{document}A and T2K anomaly

The recent anomaly observed in NOν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ u $$\\end{document}A and T2K experiments in standard three-flavor neutrino oscillation could potentially signal physics extending beyond the standard model (SM). For the NSI parameters that can accommodate this anomaly, we explore the violation of Leggett–Garg type inequalities (LGtI) within the context of three-flavor neutrino oscillations. Our analysis focuses on LGtI violations in scenarios involving complex NSI with ϵeμ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon _{e\\mu }$$\\end{document} or ϵeτ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon _{e\ au }$$\\end{document} coupling in long baseline accelerator experiments for normal and inverted mass ordering. LGtI violation is significantly enhanced in normal ordering (NO) for ϵeτ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon _{e\ au }$$\\end{document} scenario for T2K, NOν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ u $$\\end{document}A, and DUNE experiment set-up. We find that for inverted ordering (IO), in the DUNE experimental set-up above 8.5 GeV, the LGtI violation can be an indication of ϵeτ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon _{e\ au }$$\\end{document} new physics scenario.

Heavy neutrino as dark matter in a neutrinophilic U(1) model

We study the prospect of heavy singlet neutrinos as a dark matter (DM) candidate within a neutrinophilic U(1) model, where the Standard Model (SM) is extended with a U(1) gauge symmetry, and neutrino mass and oscillation parameters are explained through an inverse see-saw mechanism. The lightest of the heavy neutrinos plays the role of the DM, while the newly introduced scalars and the extra gauge boson Z′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Z'$$\\end{document} act as mediators between the dark sector and the SM sector. We show the range of model parameters where this DM candidate can be accommodated in the Weakly Interacting Massive Particle (WIMP) or Feebly Interacting Massive Particle (FIMP) scenario. The observed DM relic density (DMRD) is achieved via the new gauge boson and singlet scalar portals in the WIMP scenario, whereas within the FIMP scenario, these two particles assume a distinct yet pivotal role in generating the observed DMRD.