Prospects of light sterile neutrino searches in long-baseline neutrino oscillations

We construct a neutrino mass model based on the flavour symmetry group A4×C4×C6×C2 which accommodates a light sterile neutrino in the minimal extended seesaw (MES) scheme. Besides the flavour symmetry, we introduce a U(1) gauge symmetry in the sterile sector and also impose CP symmetry. The vacuum alignments of the scalar fields in the model spontaneously break these symmetries and lead to the construction of the fermion mass matrices. With the help of the MES formulas, we extract the light neutrino masses and the mixing observables. In the active neutrino sector, we obtain the TM2 mixing pattern with non-zero reactor angle and broken μ-τ reflection symmetry. We express all the active and the sterile oscillation observables in terms of only four real model parameters. Using this highly constrained scenario we predict $$ {\sin}^2{\theta}_{23}={0.545}_{-0.004}^{+0.003},\sin \delta =-{0.911}_{-0.005}^{+0.006},{\left|{U}_{e4}\right|}^2={0.029}_{-0.008}^{+0.009},{\left|{U}_{\mu 4}\right|}^2={0.010}_{-0.003}^{+0.003}\kern0.5em \mathrm{and}\kern0.5em {\left|{U}_{\tau 4}\right|}^2={0.006}_{-0.002}^{+0.002} $$ sin 2 θ 23 = 0.545 − 0.004 + 0.003 , sin δ = − 0.911 − 0.005 + 0.006 , U e 4 2 = 0.029 − 0.008 + 0.009 , U μ 4 2 = 0.010 − 0.003 + 0.003 and U τ 4 2 = 0.006 − 0.002 + 0.002 which are consistent with the current data.

Section: Jhep09(2020)050mentioning

confidence: 99%

Realization of the minimal extended seesaw mechanism and the TM2 type neutrino mixing

Krishnan

Mukherjee

Goswami

2020

“…As shown in [118], in a 4 × 4 unitary framework they imply the existence of 3 independent differences, say ∆P eµ , ∆P µτ , and ∆P τ e . In the 6 × 6 unitary case, we find instead that there are 10 independent differences ∆P αβ (see also [119]), while only the three of them involving just active neutrinos are experimentally relevant. Thus, one should generically expect different values for ∆P eµ , ∆P µτ , and ∆P τ e in a given seesaw-type model.…”

Section: Remarks On Cp Violation Measurementsmentioning

confidence: 81%

Type-I seesaw with eV-scale neutrinos

Branco

Penedo

Pereira

et al. 2020

We consider seesaw type-I models including at least one (mostly-)sterile neutrino with mass at the eV scale. Three distinct situations are found, where the presence of light extra neutrinos is naturally justified by an approximately conserved lepton number symmetry. To analyse these scenarios consistently, it is crucial to employ an exact parametrisation of the full mixing matrix. We provide additional exact results, including generalised versions of the seesaw relation and of the Casas-Ibarra parametrisation, valid for every scale of seesaw. We find that the existence of a light sterile neutrino imposes an upper bound on the lightest neutrino mass. We further assess the impact of light sterile states on short-and long-baseline neutrino oscillation experiments, emphasise future detection prospects, and address CP Violation in this framework via the analysis of CP asymmetries and construction of weak basis invariants. The proposed models can accommodate enough active-sterile mixing to play a role in the explanation of short-baseline anomalies.

“…In presence of a light sterile neutrino, more degrees of freedom enter the MSW effect even in the propagation of active flavor neutrinos. For the calculation of matter effects involving a light sterile neutrino, different methods [26][27][28][29] have been developed in recent years.…”

Section: Jhep09(2022)029mentioning

confidence: 99%

Matter effects of sterile neutrino in light of renormalization-group equations

Zeng

2022

The renormalization-group equation (RGE) approach to neutrino matter effects is further developed in this work. We derive a complete set of differential equations for effective mixing elements, masses and Jarlskog-like invariants in presence of a light sterile neutrino. The evolutions of mixing elements as well as Jarlskog-like invariants are obtained by numerically solving these differential equations. We calculate terrestrial matter effects in long-baseline (LBL) experiments, taking NOvA, T2K and DUNE as examples. In both three-flavor and four-flavor frameworks, electron-neutrino survival probabilities as well as the day-night asymmetry of solar neutrino are also evaluated as a further examination of the RGE approach.