arXiv subjects

R. Mohanta

Publications and source records attributed to R. Mohanta.

At least 19 recordsLinked to original sources

arXiv2026

Study of Supernova Neutrinos at ESSnuSB

In this paper, we have studied the sensitivity of the ESSnuSB far detector to supernova neutrinos. ESSnuSB is a proposed long-baseline neutrino experiment in Sweden, which will use a 538 kt water Cherenkov detector to probe the leptonic phase $\delta_{\rm CP}$ by studying the second oscillation maximum. However, given the very large detector volume, it will have an excellent sensitivity to supernova neutrinos if a supernova explosion occurs during the run-time of ESSnuSB. Motivated by this, we first estimate the expected event rates at the ESSnuSB far detector for three different supernova flux models and then we probe its capability to distinguish these flux models. Additionally, we also investigate the impact of systematic errors and detector efficiency. Our results show that depending on the model of the supernova neutrinos, the expected number of events detected at Earth varies significantly. Our results also show that the ESSnuSB far detector may have excellent potential in distinguishing these flux models depending upon the distance of the supernova explosion, systematic errors and detector efficiency.

hep-ex↗

arXiv2025

Search for Accelerator-Produced Sub-GeV Dark Matter with the NOvA Near Detector

The NuMI facility at Fermilab produces a high-intensity beam of muon neutrinos and antineutrinos, designed to study neutrino oscillations. This beam may also be a source of dark matter particles produced through a light mediator. We search for dark matter particles with masses between 1 and 200 MeV that interact with Standard Model particles via a vector portal, producing forward-scattered single-electron events in the NOvA near detector. We set limits on the dark-visible coupling based on an exposure of 2.55x10^21 protons of 120 GeV energy on the NuMI target. For the dark matter mass range 10-20 MeV, this analysis sets the tightest constraints on the coupling to date.

hep-ex↗

arXiv2017

Non-zero $θ_{13}$ and leptonic CP phase with $A_4$ Symmetry

We consider a model based on $A_4$ symmetry to explain the phenomenon of neutrino mixing. The spontaneous symmetry breaking of $A_4$ symmetry leads to a co-bimaximal mixing matrix at leading order. We consider the effect of higher order corrections in neutrino sector and find that the mixing angles thus obtained, come well within the $3σ$ ranges of their experimental values. We study the implications of this formalism on the other phenomenological observables, such as CP violating phase, Jarlskog invariant and the effective Majorana mass $|M_{ee}|$. We also obtain the branching ratio of the lepton flavour violating decay $μ\rightarrow e γ$ in the context of this model and find that it can be less than its present experimental upper bound.

hep-ph↗

arXiv2017

Impact of lepton flavour universality violation on CP violation sensitivity of long baseline neutrino oscillation experiments

The observation of neutrino oscillation as well as the recent experimental result on lepton flavor universality (LFU) violation in $B$ meson decays are indications of new physics beyond the Standard Model. Many theoretical models, which are introduced in the literature as an extension of SM to explain these observed deviations in LFU, lead to new kind of interactions so-called non-standard interaction (NSI) between the elementary particles. In this paper, we consider a model with an additional $Z'$ boson (which is quite successful in explaining the observed LFU anomalies) and analyze its effect in the lepton flavour violating (LFV) $B_d\to τ^\pm e^\mp$ decay modes. From the present upper bound of the $B_d\to τ^\pm e^\mp$ branching ratio, we obtain the constraints on the new physics parameters, which are related to the corresponding NSI parameters in the neutrino sector by $SU(2)_L$ symmetry. These new parameters are expected to have potential implications in the neutrino oscillation studies and in this work we investigate the possibility of observing the effects of these interactions in the currently running and upcoming long-baseline experiments, i.e., NOvA and DUNE respectively.

hep-ph↗

arXiv2016

Implications of lepton nonuniversality in the beauty sector

The phenomenon of CP violation in the standard model (SM) framework and the decay dynamics have been established from the data obtained from the B factories and so far we have not seen anything new. Nevertheless, there have been instances of deviations in many measured observables in the flavor sector, as far as the data and predictions are concerned. Here we will mention some deviations obtained in measurements related to lepton universality, as seen from the data, and try to understand their implications. To accommodate the observed data we will consider a leptoquark model, which seems to be one interesting model beyond the SM.

hep-ph↗

arXiv2016

Implications of lepton flavour violation on long baseline neutrino oscillation experiments

Non-standard neutrino interactions (NSIs), the sub-leading effects in the flavour transitions of neutrinos, play a crucial role in the determination of the various unknowns in neutrino oscillations, such as neutrino mass hierarchy, Dirac CP violating phase and the octant of atmospheric mixing angle. In this work, we focus on the possible implications of lepton flavour violating (LFV) NSIs, which generally affect the neutrino propagation, on the determination of the these unknown oscillation parameters. We study the effect of these NSIs on the physics potential of the currently running and upcoming long-baseline experiments, i.e., T2K, NO$ν$A and DUNE. We also check the allowed oscillation parameter space in presence of LFV NSIs.

hep-ph↗

arXiv2016

Towards extracting the best possible results from NOvA

The NuMI Off-Axis $ν_{e}$ Appearance (NO$ν$A) is the currently running leading long-baseline neutrino oscillation experiment, whose main physics goal is to explore the current issues in the neutrino sector, such as determination of the neutrino mass ordering, resolution of the octant of atmospheric mixing angle and to constrain the Dirac-type CP violating phase $δ_{CP}$. In this paper, we would like to investigate whether it is possible to extract the best possible results from NO$ν$A with a shorter time-span than its scheduled run period by analyzing its capability to discriminate the degeneracy among various neutrino oscillation parameters within four years of run time, with two years in each neutrino and antineutrino modes. Further, we study the same by adding the data from T2K experiment for a total of five years run with 3.5 years in neutrino mode and 1.5 years in antineutrino mode. We find that NO$ν$A (2+2) has a better oscillation parameter degeneracy discrimination capability compared to its scheduled run period for four years, i.e, NO$ν$A (3+1).

hep-ph↗

arXiv2016

A comprehensive study of the discovery potential of NOvA, T2K and T2HK experiments

With the recent measurement of reactor mixing angle $θ_{13}$ the knowledge of neutrino oscillation parameters that describe PMNS matrix has improved significantly except the CP violating phase $δ_{CP}$. The other unknown parameters in neutrino oscillation studies are mass hierarchy and the octant of the atmospheric mixing angle $θ_{23}$. Many dedicated experiments are proposed to determine these parameters which may take at least 10 years from now to become operational. It is therefore very crucial to use the results from the existing experiments to see whether we can get even partial answers to these questions. In this paper we study the discovery potential of the ongoing NO$ν$A and T2K experiments as well as the forthcoming T2HK experiment in addressing these questions. In particular, we evaluate the sensitivity of NO$ν$A to determine neutrino mass hierarchy, octant degeneracy and to obtain CP violation phase after running for its scheduled period of 3 years in neutrino mode and 3 years in anti-neutrino mode. We then extend the analysis to understand the discovery potential if the experiments will run for (5$ν$+5$\barν$) years and (7$ν$+3$\barν$) years. We also show how the sensitivity improves when we combine the data from (3$ν$+3$\barν$) years of NO$ν$A run with (3$ν$+2$\barν$) years of T2K and (3$ν$+7$\barν$) years of T2HK experiments. The CP violation sensitivity is marginal for T2K and NO$ν$A experiments even for ten years data taking of NO$ν$A. T2HK has a significance above 5$σ$ for a fraction of two-fifth values of the $δ_{CP}$ space. We also find that $δ_{CP}$ can be determined to be better than $35^\circ $, $21^\circ $ and $9^\circ $ for all values of $δ_{CP}$ for T2K, NO$ν$A and T2HK respectively.

hep-ph↗

arXiv2015

Predicting Leptonic CP phase by considering deviations in charged lepton and neutrino sectors

Recently, the reactor mixing angle $θ_{13}$ has been measured precisely by Daya Bay, RENO and T2K experiments with a moderately large value. However, the standard form of neutrino mixing patterns such as bimaximal, tri-bimaximal, golden ratio of types A and B, hexagonal etc., which are based on certain flavor symmetries, predict vanishing $θ_{13}$. Using the fact that the neutrino mixing matrix can be represented as $V_{\rm PMNS}=U_l^{\dagger} U_νP_ν$, where $U_l$ and $U_ν$ result from the diagonalization of the charged lepton and neutrino mass matrices and $P_ν$ is a diagonal matrix containing Majorana phases, we explore the possibility of accounting for the large reactor mixing angle by considering deviations both in the charged lepton and neutrino sector. In the charged lepton sector we consider the deviation as an additional rotation in the (12) and (13) planes, whereas in neutrino sector we consider deviations to various neutrino mixing patterns through (13) and (23) rotations. We find that with the inclusion of these deviations it is possible to accommodate the observed large reactor mixing angle $θ_{13}$, and one can also obtain limits on the CP violating Dirac phase $δ_{CP}$ and Jarlskog invariant $J_{CP}$ for most of the cases. We then explore whether our findings can be tested in the currently running NO$ν$A experiment with 3 years of data taking in neutrino mode followed by 3 years with anti-neutrino mode.

hep-ph↗

arXiv2015

Revisiting the sensitivity studies for leptonic CP violation and mass hierarchy with T2K, NOvA and LBNE experiments

Precision measurement of the neutrino mixing parameters and the determination of mass hierarchy are the primary goals of the present and upcoming neutrino experiments. In this work, we study the sensitivity of T2K,NO$ν$A and LBNE experiments to discover leptonic CP violation and the determination of neutrino mass hierarchy. We obtain the correlation between the CP violating phase $δ_{CP}$ and the mixing angles $θ_{13}$, $θ_{23}$ and the sensitivity to determine the octant of atmospheric mixing angle $θ_{23}$. The entire analysis is done for a total 10 years (5$ν$+ 5$\bar ν$) of running of T2K, NO$ν$A and LBNE experiments. Furthermore, we also consider the impact of cross section uncertainties on the CP violation sensitivity of LBNE experiment.

hep-ph↗

arXiv2014

Effect of scalar leptoquarks on the rare decays of B_s meson

We study the effect of scalar leptoquarks on some rare decays of $B_s$ mesons involving the quark level transition $b\rightarrow s$ $l^{+} l^{-}.$ In particular we consider the decays $B_{s} \rightarrow μ^{+} μ^{-}$, $\bar B_d^0 \to X_s μ^+ μ^-$ and $B_{s} \rightarrow ϕ$ $μ^{+} μ^{-}$. The leptoquark parameter space is constrained using the recently measured branching ratio of the $B_{s} \rightarrow μ^{+} μ^{-}$ process at LHCb and CMS experiments. Using such parameters we obtain the branching ratio, forward backward asymmetry and the CP asymmetry parameters in the angular distribution of $B_s \rightarrow ϕ$ $μ^+ μ^-$ process.

hep-ph↗

arXiv2013

Charged lepton correction to tribimaximal lepton mixing and its implications to neutrino phenomenology

The recent results from Daya Bay and RENO reactor neutrino experiments have firmly established that the smallest reactor mixing angle $θ_{13}$ is non-vanishing at the $5 σ$ level, with a relatively large value, i.e., $θ_{13}\approx 9^{\circ}$. Using the fact that the neutrino mixing matrix can be represented as $V_{\rm PMNS}=U_l^{\dagger} U_ν P_ν$, where $U_l$ and $U_ν$ result from the diagonalization of the charged lepton and neutrino mass matrices and $P_ν$ is a diagonal matrix containing the Majorana phases and assuming the tri-bimaximal form for $U_ν$, we investigate the possibility of accounting for the large reactor mixing angle due to the corrections of the charged lepton mixing matrix. The form of $U_{l}$ is assumed to be that of CKM mixing matrix of the quark sector. We find that with this modification it is possible to accommodate the large observed reactor mixing angle $θ_{13}$. We also study the implications of such corrections on the other phenomenological observables.

hep-ph↗

arXiv2012

Possibility of observing Leptonic CP violation with perturbed Democratic mixing patterns

The Daya Bay Collaboration has recently reported the precise measurement of $θ_{13}\simeq 8.8^\circ \pm 0.8^\circ $ or $θ_{13} \neq 0$ at 5.2 σlevel. The observed non-zero $θ_{13}$ can be accommodated by some general modifications to the Democratic mixing matrix. Using such matrices we study the possibility of observing non-zero CP violation in the leptonic sector.

hep-ph↗

arXiv2012

Neutrino mixing matrices with relatively large $θ_{13}$ and with texture one-zero

The recent T2K, MINOS and Double Chooz oscillation data hint a relatively large $θ_{13}$, which can be accommodated by some general modification of the Tribimaximal/Bimaximal/Democratic mixing matrices. Using such matrices we analyze several Majorana mass matrices with texture one-zero and show whether they satisfy normal or inverted mass hierarchy and phenomenologically viable or not.

hep-ph↗

arXiv2011

Study of some rare decays of B_s meson in the fourth generation model

We study some rare decays of $B_s$ meson governed by the quark level transitions $ b \to s$, in the fourth generation model popularly known as SM4. Recently it has been shown that SM4, which is a simple extension of the SM3, can successfully explain several anomalies observed in the CP violation parameters of $B$ and $B_s$ mesons. We find that in this model due to the additional contributions coming from the heavy $t'$ quark in the loop, the branching ratios and other observables in rare $B_s$ decays deviate significantly from their SM values. Some of these modes are within the reach of LHCb experiment and search for such channels are strongly argued.

hep-ph↗

arXiv2011

Study of some B_s to f_0(980) decays in the fourth generation model

We study some non leptonic and semileptonic decays of $B_s$ meson into a final scalar meson $f_0(980)$ in the fourth quark generation model. Since the $f_0(980)$ meson is dominantly composed of ($s \bar s $) pair, the mixing induced CP asymmetry in the decay mode $B_s \to J/ψf_0(980)$ would {\it a priori} give $\sin 2 β_s$, where $β_s$ is the $B_s-\bar B_s$ mixing phase. In the standard model this asymmetry is expected to be vanishingly small. We find that in the fourth generation model a large mixing induced CP asymmetry could be possible for this process. Similarly the branching ratios of the rare semileptonic decays $B_s \to f_0(980) l^+ l^-$ and $B_s \to f_0(980) ν\bar ν$ are found to be enhanced significantly from their corresponding standard model values.

hep-ph↗

arXiv2011

Effect of FCNC mediated Z boson on lepton flavor violating decays

We study the three body lepton flavor violating (LFV) decays $μ^- \to e^- e^+ e^-$, $τ^- \to l_i^- l_j^+ l_j^-$ and the semileptonic decay $τ\to μϕ$ in the flavor changing neutral current (FCNC) mediated $Z$ boson model. We also calculate the branching ratios for LFV leptonic B decays, $B_{d,s} \to μe$, $B_{d,s} \to τe$, $B_{d,s} \to τμ$ and the conversion of muon to electron in Ti nucleus. The new physics parameter space is constrained by using the experimental limits on $μ^- \to e^- e^+ e^-$ and $τ^- \to μ^- μ^+ μ^-$. We find that the branching ratios for $τ\to eee $ and $τ\to μϕ$ processes could be as large as $\sim {\cal O}(10^{-8})$ and ${\rm Br}B_{d,s} \to τμ, τe) \sim {\cal O}(10^{-10})$. For other LFV B decays the branching ratios are found to be too small to be observed in the near future.

hep-ph↗

arXiv2010

Fourth generation effect on $Λ_b$ decays

The rare decays of $Λ_b$ baryon governed by the quark level transitions $ b \to s$, are investigated in the fourth quark generation model popularly known as SM4. Recently it has been shown that SM4, which is a very simple extension of the standard model, can successfully explain several anomalies observed in the CP violation parameters of $B$ and $B_s$ mesons. We find that in this model due to the additional contributions coming from the heavy $t'$ quark in the loop, the branching ratios and other observables in rare $Λ_b$ decays deviate significantly from their SM values. Some of these modes are within the reach of LHCb experiment and search for such channels are strongly argued.

hep-ph↗