arXiv subjects

Sudhanwa Patra

Publications and source records attributed to Sudhanwa Patra.

At least 37 records · Page 2Linked to original sources

arXiv2025

Impact of CP violation searches at MOMENT experiment with sterile neutrinos

We examine the scope of the MOMENT experiment in the context of CP violation searches with the presence of extra eV scale sterile neutrino. MOMENT is a proposed medium baseline neutrino oscillation experiment using muon beams for neutrinos production, making it advantageous over $π_0$ background and other technical difficulties. We work over the first oscillation maxima which matches the peak value of flux with a run time of 5 years for both neutrino and anti-neutrino modes. We perform the bi-probability studies for both 3 and 3+1 flavor mixing schemes. The CP violation sensitivities arising from the fundamental CP phase $δ_{13}$ and unknown CP phase $δ_{14}$ are explored at the firm footing. Slight deteriorations are observed in CP violations induced by $δ_{13}$ as the presence of sterile neutrino is considered. We also look at the reconstruction of CP violations phases $δ_{13}$ and $δ_{14}$ and the MOMENT experiment shows significant capabilities in the precise measurement of $δ_{13}$ phase.

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arXiv2025

Left-Right Symmetric Neutrino Mass Model without Scalar Bi-doublet

We consider a left-right symmetric model with an $SU(2)_L$ and an $SU(2)_R$ scalar doublet but without the scalar bidoublet. The charged fermion masses in this model are generated via a universal seesaw mechanism. We add a set of three gauge singlet neutral fermions with Majorana masses of the order of a TeV. The masses for the left-handed neutrinos are naturally small in this model because they occur only at one-loop and are generated through a see-saw mechanism. By an appropriate choice of the Yukawa couplings of the $SU(2)_L$ doublet and the masses of the gauge singlet fermions, it is possible to implement resonant leptogenesis at TeV scale. The right-handed sector of the model, through appropriate values of the Yukawa couplings of the $SU(2)_R$ doublet, leads to a warm dark matter candidate in the lightest right-handed neutrino with a mass of a few keV and an observable effective electron mass for neutrinoless double beta decay $m_{ββ}$.

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arXiv2025

Multipartite dark matter in a gauge theory of leptons

The classical conservation of the lepton number is an accidental symmetry present in the Standard Model (SM). Thus, we consider here a scenario where the SM is extended with a U(1) gauge group, promoting the lepton number to a local symmetry. The gauge anomaly cancellations necessitate the extension of the particle spectrum with several beyond the SM (BSM) particle fields. The extended lepton gauge group breaks around the TeV scale via spontaneous symmetry breaking, and a $Z_2$ symmetry remains, which ensures the stability of the light $Z_2$ odd BSM particles. Interestingly, the particle spectrum of the model has two distinct dark sectors, with one having a Dirac-type DM and the other one containing a Majorana-type DM, thus resulting in a multipartite dark matter scenario. We have explored the available parameter space consistent with the observed dark matter relic density and direct detection measurements for both of the DM particles. Having a Majorana dark matter, we have also studied for the gamma line signatures to constrain the parameter space from the indirect dark matter detection experiments like FermiLAT and CTA.

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arXiv2025

Signals of eV-scale sterile neutrino at long baseline neutrino experiments

While most of the results of the neutrino oscillation experiments can be accommodated within the standard paradigm of three active flavor, there are tantalizing hints of an light eV-scale sterile neutrino from anomalous results of a few short baseline experiments. This additional light sterile neutrino is expected to leave an imprint on the physics observables pertaining to standard unknowns such as determination of the Dirac-type leptonic $CP$ phase, $δ_{13}$, the question of neutrino mass hierarchy and the octant of $θ_{23}$. The upcoming long baseline neutrino experiments such as T2HK, DUNE and P2O will be sensitive to active - sterile mixing. In the present work, we examine and assess the capability of these long baseline experiments to probe the sterile neutrino at the level of probabilities and event rates. We perform a detailed study by taking into account the values of parameters that are presently allowed and (a) study the impact on $CP$ violation by examining the role played by various appearance and disappearance channels, (b) address the question of disentangling the intrinsic effects from extrinsic effects in the standard paradigm as well as three active plus one light sterile neutrino, and finally (c) assess the ability of these long baseline experiments to distinguish between the two scenarios. Our results indicate that for the true values of sterile parameters and for all values of $δ_{13}$, the sensitivity of P2O is the lowest while the sensitivity of T2HK is modest ($<3\,σ$) and the sensitivity of DUNE is $> 3\,σ$. For larger values of the sterile mixing angles, there is an improvement in the sensitivity for all the three considered experiments.

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arXiv2024

Imprints of LGI violation in Mesons

Quantum mechanics has always proven emphatically as one of the main cornerstones in all of science since its inception. Initially, it has also faced many skeptics from many scientific proponents of its complete description of reality. However, John Bell once devised a theorem on quantitative grounds to show how local realism is expressed in quantum mechanics. As Bell's inequality claims the non-existence of local hidden variable theories, on the same footing, we have Leggett-Garg's Inequality (LGI), which sets a quantum-classical limit for temporally correlated quantum systems. In the context of particle physics, specially in the field of neutrino and meson oscillations, one can conveniently implement LGI to test the quantum foundations at the probability level. Here, we discuss the significant LGI violation characteristics in B- and K- meson oscillations, taking into account their decoherence, CP violation, and decay parameters. We have emphasized the fact that \textit{Tsirelson} bounds can be achieved under certain conditions. Our focal point is to show the signature of these bounds that appears only to specific alterations of decay and decoherence effects. Also, we discuss and comment on the behavior or effect of decoherence and decay widths playing out from the perspective of LGI by taking their available values from various experiments. This may help us to understand the underlying principles and techniques of neutral meson open quantum systems.

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arXiv2024

Singlet-Doublet Fermionic Dark Matter in Gauge Theory of Baryons

We are considering a minimal $U(1)_B$ extension of the Standard Model (SM) by promoting the baryon number as a local gauge symmetry to accommodate a stable dark matter (DM) candidate. The gauge theory of baryons induces non-trivial triangle gauge anomalies, and we provide a simple anomaly-free solution by adding three exotic fermions. A scalar $S$ spontaneously breaks the $U(1)_B$ symmetry, leaving behind a discrete $Z_2$ symmetry that ensures the stability of the lightest exotic fermion was originally introduced to cancel the triangle gauge anomalies. Scenarios with weakly interacting DM candidates having non-zero hypercharge usually face stringent constraints from experimental bounds on the DM spin-independent direct-detection (SIDD) cross-section. In this work, we consider a two-component singlet-doublet fermionic dark matter scenario, which significantly relaxes the constraints from bounds on the DM SIDD cross-section for suppressed singlet-doublet mixing. We show that the model offers a viable parameter space for a cosmologically consistent DM candidate that can be probed through direct and indirect searches, collider experiments, and gravitational wave (GW) experiments.

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arXiv2024

Leptogenesis in a Left-Right Symmetric Model with double seesaw

We explore the connection between low-scale CP-violating Dirac phase~$(δ)$ and high-scale leptogenesis in a Left-Right Symmetric Model (LRSM) with scalar bidoublet and doublets. The fermion sector of the model is extended with one sterile neutrino~$(S_L)$ per generation to implement a double seesaw mechanism in the neutral fermion mass matrix. The double seesaw is performed via the implementation of type-I seesaw twice. The first seesaw facilitates the generation of Majorana mass term for heavy right-handed (RH) neutrinos~$(N_R)$, and the light neutrino mass becomes linearly dependent on $S_L$ mass in the second. In our framework, we have taken charge conjugation ($C$) as the discrete left-right (LR) symmetry. This choice assists in deriving the Dirac neutrino mass matrix ($M_D$) in terms of the light and heavy RH neutrino masses and light neutrino mixing matrix $U_{PMNS}$ (containing $δ$). We illustrate the viability of unflavored thermal leptogenesis via the decay of RH neutrinos by using the obtained $M_D$ with the masses of RH neutrinos as input parameters. A complete analysis of the Boltzmann equations describing the asymmetry evolution is performed in the unflavored regime, and it is shown that with or without Majorana phases, the CP-violating Dirac phase is sufficient to produce the required asymmetry in the leptonic sector within this framework for a given choice of input parameters. Finally, we comment on the possibility of constraining our model with the current and near-future oscillation experiments, which are aimed at refining the value of $δ$.

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arXiv2024

Gauge coupling unification in a minimal non-supersymmetric $E_6$ GUT

We consider a minimal renormalizable non-supersymmetric $E_6$ Grand Unified Theory using fundamental representation $27$ for fermions and scalars. The scalar with adjoint representation ${78}$ is also taken for direct breaking of $E_{6}$ to SM. The proposed model, guided by TeV-scale vector-like fermions and scalar leptoquark offer successful gauge unification even in the absence of any intermediate symmetry. Embedded with threshold corrections, it is shown to be compatible with the present experimental limit on proton decay lifetime. The unique feature of the model shows that, the GUT threshold corrections to the unification mass, is controlled by superheavy gauge bosons only, thereby minimising the uncertainty of the GUT predictions. The scalar leptoquark and vector-like fermions residing in $27$ representation can explain flavor physics anomalies like $R_{D^{(\ast)}}$ as reported by the LHCb collaboration and the muon anomalous magnetic moment reported by the recent muon $g-2$ experiment at Fermilab. The model can also predict a sub-eV scale neutrino at one-loop level via exchange of $W$ and $Z$ gauge bosons through MRIS mechanism.

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arXiv2023

Geometrical Interpretation of Neutrino Oscillation with decay

The geometrical representation of two-flavor neutrino oscillation represents the neutrino's flavor eigenstate as a magnetic moment-like vector that evolves around a magnetic field-like vector that depicts the Hamiltonian of the system. In the present work, we demonstrate the geometrical interpretation of neutrino in a vacuum in the presence of decay, which transforms this circular trajectory of neutrino into a helical track that effectively makes the neutrino system mimic a classical damped driven oscillator. We show that in the absence of the phase factor $ξ$ in the decay Hamiltonian, the neutrino exactly behaves like the system of nuclear magnetic resonance(NMR); however, the inclusion of the phase part introduces a $CP$ violation, which makes the system deviate from NMR. Finally, we make a qualitative discussion on under-damped, critically-damped, and over-damped scenarios geometrically by three different diagrams. In the end, we make a comparative study of geometrical picturization in vacuum, matter, and decay, which extrapolates the understanding of the geometrical representation of neutrino oscillation in a more straightforward way.

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arXiv2023

CDF II W-mass anomaly and SO(10) GUT

The W-mass anomaly has yet to be established, but a huge proliferation of articles on the subject established the rich potential of such event. We investigate the SO(10) GUT constraints from the recently reported W-mass anomaly. We consider both Supersymmetric (SUSY) and non-supersymmetric (non-SUSY) grand unified theories by studying renormalization group equations (RGEs) for gauge coupling unification and their predictions on proton decay. In the non-SUSY models, single-stage unification is possible if one include a light (around TeV) real triplet Higgs scalar. However, these models predict speedy proton decay, inconsistent with the present experimental bound on the proton decay. This situation may be improved by including newer scalars and new intermediate-mass scales, which are present in the $SO(10)$ GUTs. The standard model is extended to a left-right symmetric model (LR), and the scale of LR breaking naturally introduces the intermediate scale in the model. A single-stage unification is possible even without including any triplet Higgs scalar in a minimal supersymmetric standard model.

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arXiv2023

Cogenesis of visible and dark sector asymmetry in a minimal seesaw framework

Recently there is a renewed interest in exploring the Dark sector of the universe in a more constrained way. Particularly in [1], the FIMP ( Feebly Interacting Massive Particle) scenario was shown to be realized with a minimal extension of the SM with three sterile neutrinos in the spirit of νMSM. In this paper, we show that without invoking any additional symmetries of the model, we can realize the idea of ADM (Asymmetric Dark Matter) signaling a common origin of the matter-anti-matter asymmetries in visible as well as Dark sectors. The model allows for a range of dark matter masses, 1 - 100keV, with correct active neutrino masses through the Type-I seesaw mechanism. Thus, the model explains the neutrino masses, Dark Matter abundance and replicates matter-anti-matter asymmetry of the visible sector in the Dark sector, all in a version of the νMSM. The asymmetry in the dark sector is manifested in the predominance of one parity of the heavy neutrinos in the comoving frame, which should be determinable in the ongoing experiments.

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arXiv2023

Neutrinoless double beta decay in Left-Right symmetric model with double seesaw mechanism

We discuss a left-right (L-R) symmetric model with the double seesaw mechanism at the TeV scale generating Majorana masses for the active left-handed (LH) flavour neutrinos $ν_{αL}$ and the heavy right-handed (RH) neutrinos $N_{βR}$, $α,β= e,μ,τ$, which in turn mediate lepton number violating processes, including neutrinoless double beta decay. The Higgs sector is composed of two Higgs doublets $H_L$, $H_R$, and a bi-doublet $Φ$. The fermion sector has the usual for the L-R symmetric models quarks and leptons, along with three $SU(2)$ singlet fermion $S_{γL}$. The choice of bare Majorana mass term for these sterile fermions induces large Majorana masses for the heavy RH neutrinos leading to two sets of heavy Majorana particles $N_j$ and $S_k$, $j,k=1,2,3$, with masses $m_{N_j} \ll m_{S_k}$. Working with a specific version of the model in which the $ν_{αL} - N_{βR}$ and the $N_{βR} - S_{γL}$ Dirac mass terms are diagonal, and assuming that $m_{N_j} \sim (1 - 1000)$ GeV and ${\rm max}(m_{S_k}) \sim (1 - 10)$ TeV, $m_{N_j} \ll m_{S_k}$, we study in detail the new ``non-standard'' contributions to the $0νββ$ decay amplitude and half-life arising due to the exchange of virtual $N_j$ and $S_k$. We find that in both cases of NO and IO light neutrino mass spectra, these contributions are strongly enhanced and are dominant at relatively small values of the lightest neutrino mass $m_{1(3)} \sim (10^{-4} - 10^{-2})$ eV over the light Majorana neutrino exchange contribution. In large part of the parameter space, the predictions of the model for the $0νββ$ decay generalised effective Majorana mass and half-life are within the sensitivity range of the planned next generation of neutrinoless double beta decay experiments LEGEND-200 (LEGEND-1000), nEXO, KamlAND-Zen-II, CUPID, NEXT-HD.

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arXiv2022

Numerically analyzing self-interacting dark matter

We consider the scenario of self-interacting dark matter(SIDM) with a light mediator in a model-independent way, which can alleviate two long-standing issues of the small scale cosmology namely cusp vs. core and too-big-to-fail. A Yukawa potential is chosen to achieve mediator exchange between DM particles as part of their self-interactions. The dynamics of self-interacting transfer cross-section are studied for a range of mediator mass($m_Z'$). Also, a relationship is established between the cross-section and DM particles' relative velocity, which ensures the solution to the DM crisis at small scales. Our obtained numerical results are efficient compared to the earlier works in the context that a lesser number of $\ell$ modes have been used by us to achieve the same level of accuracy in the cross-section calculations. For a better understanding of the SIDM parameter space, we perform an analytical analysis on the dependence of transfer cross-section over the other important SIDM parameters using a Hulthén potential which is similar in its behavior to Yukawa potential. A detailed evolution of particle dynamics using the Boltzmann equation and the effect of Sommerfeld enhancement on such calculations has also been studied here. We also provide a minimal anomaly-free leptophilic extension of the standard model, that can incorporate SIDM and its mediator candidate in the framework.

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arXiv2022

Flavour anomalies and dark matter assisted unification in $SO(10)$ GUT

With the recent experimental hint of new physics from flavor physics anomalies, combined with the evidence from neutrino mass and dark matter, we consider a minimal extension of SM with a scalar leptoquark and a fermion triplet. The scalar leptoquark with couplings to leptons and quarks can explain lepton flavor non-universality observables $R_K$, $R_{K^{(*)}}$, $R_{D^{(*)}}$ and $R_{J/ψ}$. Neutral component of fermion triplet provides current abundance of dark matter in the Universe. The interesting feature of the proposal is that the minimal addition of these phenomenologically rich particles (scalar leptoquark and fermion triplet) assist in realizing the unification of the gauge couplings associated with the strong and electroweak forces of standard model when embedded in the non-supersymmetric $SO(10)$ grand unified theory. We discuss on unification mass scale and the corresponding proton decay constraints while taking into account the GUT threshold corrections.

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arXiv2022

Zoom in muon survival probability with sterile neutrino for CP and T-violation

We present the approximated analytic expressions for the muon survival probability in a $3+1$ mixing scenario in the presence of matter effect using the S-matrix formalism. We find that all the individual terms contributing to the muon survival probability can significantly reduce to just three contributions. The leading order contribution comes from the three flavor muon survival probability followed by the two sub-leading contributions arising from active-sterile mixing. Furthermore, to more simplify the results we adopt the well known series expansion relations about mass-hierarchy parameter $α= Δm^2_{21} / Δm^2_{31}$ and the mixing angle $\sin θ_{13}$ in the vanishing limit of $α^2$. We discuss the relevance of muon survival probability to probe the CP and T-violation studies coming from the new physics. We also compare the analytic relation between vacuum and matter contributions to the muon survival probability at the leading order. Finally, we comment on the probability behavior at the various long baselines relevant to understand the atmospheric-neutrino sector and to resolve the existing mass-hierarchy problem.

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arXiv2022

MSW effect with quark matter: Neutron Star as a case study

With the recent findings from various astrophysical results hinting towards possible existence of strange quark matters with the baryonic resonances such as $Λ^0, Σ^0, Ξ, Ω$ in the core of neutron stars, we investigate the MSW effect, in general, in quark matter. We find that the resonance condition for the complete conversion of down-quark to strange quark requires estremely large matter density ($ρ_u \simeq 10^{5}\,\mbox{fm}^{-3} $). Nonetheless the neutron stars provide a best condition for the conversion to be statistically significant which is of the same order as is expected from imposing charge neutrality condition. This has a possibility of resolving the hyperon puzzle as well as the equation of state for dense baryonic matter.

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arXiv2022

Determining neutrino mass hierarchy in an extended Left-Right model

We derive the lower bound on absolute scale of lightest neutrino mass for normal hierarchy and inverted hierarchy pattern of light neutrinos by studying the new physics contributions to charged lepton flavour violating decays and neutrinoless double beta decay in the framework of a TeV scale left-right symmetric model. Neutrino mass is generated in the model via type-II seesaw dominance with the help of a heavy sterile neutrino. This scenario allows large light-heavy neutrino mixing and the mixing facilitates new channels for neutrinoless double beta decay and lepton flavour violating decays. We express all the model parameters in terms of oscillation parameters in order to constrain light neutrino mass scale and extract information on neutrino mass hierarchy.

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arXiv2022

Study of matter effects in the presence of sterile neutrino using OMSD approximation

We discuss the transition and survival probabilities in $3+1$ neutrino flavor mixing scenario in presence of matter effects. We adopt the well-known OMSD(One Mass Scale Dominance) approximation to carry out our analysis. After that we perform series expansion about $\sin θ_{13}$ term upto second order. We find that our results are consistent with the already existing $α- \sin θ_{13}$ approximated relations in the limit of vanishing $α$ and phases involving sterile neutrinos. We also figure out that survival transition probability becomes independent of the fundamental and sterile CP phases under our formalism. Hence, it provides us a new way to look at only matter effects contribution to oscillation probability. Also, the transition probability at the same time gives an independent study of CP-violation arising from the sterile phases, in the vicinity of fundamental CP violation phase. We provide the relation for the atmospheric probability in the presence of matter by performing the series expansion upto linear order about parameter $A (= 2EV)$, with V being the effective matter potential under OMSD approximation.

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