arXiv subjects

Mayengbam Kishan Singh

Publications and source records attributed to Mayengbam Kishan Singh.

7 recordsLinked to original sources

arXiv2026

Simple Modular $S_3$ Models for Lepton Masses and Mixing

We perform a systematic study of an economical class of modular $S_3$ lepton-flavor models without enlarging the continuous gauge symmetry or introducing right-handed neutrinos or additional flavon fields. We provide a complete classification of all inequivalent realizations allowed by the $S_3$ singlet--doublet representation structure and the admissible modular-weight assignments. Their phenomenological viability is investigated for both normal ordering (NO) and inverted ordering (IO) using Bayesian model comparison and parameter-correlation analysis based on current neutrino-oscillation data. We identify 18 viable models for NO and 19 for IO, with 14 satisfying the experimental constraints in both orderings. The viable models successfully accommodate current neutrino-oscillation data while yielding nontrivial predictions for leptonic CP violation, Majorana phases, and observables probing the absolute neutrino-mass scale. Among these predictions, the absolute-mass observables provide the clearest separation between the two orderings. At the best-fit points, the predicted ranges of the effective electron-neutrino mass ($m_β$) are completely disjoint between NO and IO, whereas those of the sum of neutrino masses ($\sum_i m_i$) and the effective Majorana mass ($m_{ββ}$) show only partial separation. The IO models generally predict a higher absolute neutrino-mass scale and are consequently more strongly constrained by cosmological observations and more accessible to neutrinoless double-beta-decay searches. Our results show that, despite its economical field content, the modular $S_3$ framework accommodates a diverse set of phenomenologically viable lepton-flavor realizations with experimentally testable predictions.

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arXiv2026

Neutrino mass and mixing, resonant leptogenesis and charged lepton flavor violation in a minimal inverse seesaw model with $S_4$ symmetry

We propose a minimal inverse seesaw model with $S_4$ symmetry for the Majorana neutrinos with only one real ($m_0$)-and two complex ($α, β$) parameters in neutrino sector which gives reasonable predictions for the neutrino oscillation parameters, the observed baryon asymmetry of the Universe and the charged lepton flavor violation. The resulting model reveals a favor for normal neutrino mass ordering, a higher octant of $θ_{23}$ and a lower half-plane of Dirac CP violation phase. The predictions of the model for sum of neutrino masses and the effective Majorana neutrino mass are centered around 58.98 meV and 6.2 meV, respectively. The model also provides the predictions of the baryon asymmetry and charged lepton flavour violation processes which are consistent with the experimental observations.

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arXiv2025

3+1 neutrino mixings model with $A_4$ triplet Majorana neutrino

We study a 3+1 active-sterile neutrino mixings model using an $A_4$ triplet right-handed neutrino $ν_R$ and a singlet eV-scale sterile neutrino under $A_4\times Z_3 \times Z_2$ discrete symmetry. Four scalar flavons are considered to reproduce neutrino oscillation parameters within the experimental 3$σ$ range. The model also studies the effective mass parameter in neutrinoless double beta decay experiments. Deviation from $μ-τ$ symmetry in the active neutrino mass matrix is generated through an antisymmetric interaction of $ν_R$. This model successfully explains active-sterile neutrino mixings consistent with the cosmological upper bound on the sum of active neutrino mass $\sum m_i < 0.113$ eV (0.145 eV) in NH(IH).

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arXiv2024

Exploring active-sterile neutrino mixings models in MES mechanism using modular $S_3$ symmetry

We study the minimal extended seesaw mechanism with one sterile neutrino in a 3+1 framework using modular $S_3$ symmetry. The active-sterile neutrino models are classified based on the assignments of $S_3$ representations and modular weights of the left-handed lepton doublets, triplet right-handed neutrino, and sterile neutrino. No scalar flavons are considered, and the flavor symmetry is broken by the vacuum expectation value (vev) of the modulus $τ$. For a particular set of representations of the Leptons and Higgs field, we obtain eleven (11) different models based on different modular weights of charged lepton $(k_L)$ and right-handed neutrino ($k_N$). Out of these, we consider two models, which are discriminated by carrying out the numerical analysis so that the parameter space in each model can fit the latest neutrino oscillation data at 3$σ$. The Planck cosmological bound on the upper limit of the sum of the active neutrino masses $\sum m_i <0.12$eV is also considered. Finally, the best-fit parameters of the neutrino observables and model predictions are evaluated using the minimum $χ^2$ analysis.

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arXiv2024

Modular $A_4$ symmetry in 3+1 active-sterile neutrino masses and mixings

Motivated by the significance of modular symmetry in generating neutrino masses and flavor mixings, we apply the modular $A_4$ symmetry in a 3+1 scheme of active-sterile neutrino mixings. Neutrino oscillation observables in the 3$σ$ range are successfully reproduced through the vacuum expectation value of the modulus $τ$. We also study phenomenologies related to the effective neutrino masses $m_β$ in tritium beta decay and $m_{ββ}$ in neutrinoless double beta decay. Mixings between active neutrinos and eV scale sterile neutrino are analyzed in detail. The model also predicts the Dirac CP-violating phase $δ_{CP}$ and Majonara phases $α$ and $β$. The best-fit values of the neutrino mixing angles and ratios of two mass-squared differences are determined using minimum $χ^2$ analysis. The best-fit values of the neutrino oscillation observables are predicted as $\sin^2θ_{23}=0.573,$ $\sin^2θ_{12}=0.300,$ $ \sin^2θ_{13}=0.022$ and $r = 0.172$ for NH while $\sin^2θ_{23}=0.550,$ $\sin^2θ_{12}=0.303,$ $ \sin^2θ_{13}=0.022$ and $r = 0.171$ for IH. We also observe that the predictions of effective neutrino mass parameters in the 3+1 scheme are significantly different from the three neutrino paradigm.

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arXiv2024

A randomly generated Majorana neutrino mass matrix using Adaptive Monte Carlo method

A randomly generated complex symmetric matrix using Adaptive Monte Carlo method, is taken as a general form of Majorana neutrino mass matrix, which is diagonalized by the use of eigenvectors. We extract all the neutrino oscillation parameters i.e. two mass-squared differences ($Δm_{21}^2$ and $Δm_{32}^2$ ), three mixing angles ($θ_{12}$, $θ_{13}$, $θ_{23}$) and three phases i.e. one Dirac CP violating phase ($δ_{CP}$) and two Majorana phases ($α$ and $β$). The charge-parity (CP) violating phases are extracted from the mixing matrix constructed with the eigenvectors of the Hermitian matrix formed by the complex symmetric matrix. All the neutrino oscillation parameters within 3$σ$ bound are allowed in both normal hierarchy (NH) and inverted hierarchy (IH) consistent with the latest Planck cosmological upper bound, $\sum\vert m_i\vert<0.12$ eV. This latest cosmological upper bound is allowed only in three cases of zero texture for $m_{11}=0$; $m_{11},m_{12}=0$ and $m_{11},m_{13}=0$ in normal hierarchy whereas none of zero texture is allowed in inverted hierarchy. We also study effective neutrino masses $m_β$ in tritium beta decay and $m_{ββ}$ in neutrinoless double beta decay.

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arXiv2023

KeV dark matter in minimal extended seesaw model and its predictions in neutrinoless double beta decay and baryogenesis

We develop an $A_4 \times Z_4 \times Z_2$ symmetry extension of Standard Model under the minimal extended seesaw (MES) mechanism which successfully predicts neutrino masses and mixings patterns. This model breaks $μ-τ$ symmetry of neutrino mass matrix and explains leptonic mixing with non-zero $θ_{13}$. We study the phenomenological results of the keV-scale sterile neutrino as a dark matter candidate along with other phenomenologies such as neutrino oscillation observables, neutrinoless double beta decay, baryogenesis via leptogenesis, etc. Dirac CP-violating phase $δ_{CP}$ and two Majorana phases $α$ and $β$ are also calculated from the leptonic mixing matrix. Best-fit values of the model parameters and neutrino observables are calculated from $χ^2$ analysis. The model predicts best-fit values of neutrino mixing angles to be $\sin^2θ_{23}=0.555,\ \sin^2θ_{12}=0.301$ and $\sin^2θ_{13}=0.022$ for normal hierarchy. Significant results consistent with experimental data are also observed for effective neutrino mass $m_{ββ} \sim (0.97 - 5.02)$ meV, effective electron mass $m_β \sim (0.084-0.41)$eV and sum of active neutrino masses $\sum m_{i} < 0.12$ eV. The model does not favour Inverted hierarchy at the 3$σ$ level with the given parameter space.

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