arXiv subjects

Soumya C

Publications and source records attributed to Soumya C.

3 recordsLinked to original sources

arXiv2020

Light sterile neutrinos and their implications on currently running long-baseline and neutrinoless double beta decay experiments

Recent $ν_e$ appearance data from the Mini Booster Neutrino Experiment (MiniBooNE) are in support of the excess of events reported by the Liquid Scintillator Neutrino Detector (LSND), which provides an indirect hint for the existence of eV-scale sterile neutrino. As these sterile neutrinos can mix with the standard active neutrinos, in this paper we explore the effect of such active-sterile mixing on the determination of various oscillation parameters by the currently running long-baseline neutrino experiments T2K and NO$ν$A. We find that the existence of sterile neutrino can lead to new kind of degeneracies among these parameters which would substantially deteriorate the mass hierarchy sensitivity of NO$ν$A experiment. We further notice that the inclusion of data from T2K experiment helps in resolving the degeneracies. The impact of new CP violating phases $δ_{14}$ and $δ_{34}$ on the maximal CP-violation exclusion sensitivity for NO$ν$A experiment has also been illustrated. Finally, we discuss the implication of such light sterile neutrinos on neutrinoless double beta decay processes in line with recent experimental results, as well as on the sensitivity reach of future experiments.

hep-ph↗

arXiv2020

Exploring the effect of Lorentz invariance violation with the currently running long-baseline experiments

Neutrinos are the fundamental particles, blind to all kind of interactions except the weak and gravitational. Hence, they can propagate very long distances without any deviation. This characteristic property can thus provide an ideal platform to investigate Planck suppressed physics through their long distance propagation. In this work, we intend to investigate CPT violation through Lorentz invariance violation (LIV) in the long-baseline accelerator based neutrino experiments. Considering the simplest four-dimensional Lorentz violating parameters, for the first time, we obtain the sensitivity limits on the LIV parameters from the currently running long-baseline experiments T2K and NO$ν$A. In addition to this, we show their effects on mass hierarchy and CP violation sensitivities by considering NO$ν$A as a case study. We find that the sensitivity limits on LIV parameters obtained from T2K are much weaker than that of NO$ν$A and the synergy of T2K and NO$ν$A can improve these sensitivities. All these limits are slightly weaker ($2 σ$ level) compared to the values extracted from Super-Kamiokande experiment with atmospheric neutrinos. Moreover, we observe that the mass hierarchy and CPV sensitivities are either enhanced or deteriorated significantly in the presence of LIV as these sensitivities crucially depend on the new CP-violating phases. We also present the correlation between $\sin^2 θ_{23}$ and the LIV parameter $|a_{αβ}|$, as well as $δ_{CP}$ and $|a_{αβ}|$.

hep-ph↗

arXiv2018

Non-unitary lepton mixing in an inverse seesaw and its impact on the physics potential of long-baseline experiments

In this paper, we consider the low-energy scale inverse seesaw mechanism in which the observed neutrino mass and lepton mixing are explained by introducing right handed neutrinos and the gauge-singlet fermions with experimentally testable energy scale. Moreover, the presence of such new fermions leads to unitarity violation in lepton mixing due to significantly large mixing between active neutrinos and the heavy fermions. In addition to this, such large lepton mixing also gives rise to potentially large lepton flavor violation, which allows to constrain the non-unitarity parameters via lepton flavor violating decays ($l_i \to l_j γ$). We make use of these constraints on non-unitarity parameters and investigate their effects on the determination of current unknown oscillation parameters at long-baseline experiments. We find that non-unitarity parameters are sensitive to NO$ν$A experiment. However, it is observed that NO$ν$A experiment is not expected to improve the current knowledge of non-unitarity parameter $η_{21}$. We also find that the sensitivities to current unknowns are deteriorated significantly in presence of non-unitary lepton mixing and these sensitivities crucially depend upon the new CP-violating phase in the non-unitary mixing. Further, we find that the degeneracy resolution capability of NO$ν$A experiment is reduced in the presence of non-unitarity parameters. However, the synergy between the currently running experiments T2K and NO$ν$A can improve the parameter degeneracy resolution and hence there is enhancement in the sensitivities of unknowns.

hep-ph↗