arXiv subjects

Suchismita Sahoo

Publications and source records attributed to Suchismita Sahoo.

At least 19 recordsLinked to original sources

arXiv2026

Signature of (axial)vector operators in $B_c\to D_s^{(*)} μ^+ μ^-$ decays

The persistent anomalies observed in $B$ mesons related to $b \to s μ^+ μ^-$ transitions point to the potential for new physics beyond the Standard Model. To explore this further, we conduct an analysis of the exclusive semileptonic decays $B_c\to D_s^{(*)} μ^+ μ^-$ within an effective field theory formalism. We perform a global fit to new (axial)vector couplings using the current experimental data for $b \to s μ^+ μ^-$ transitions. We compute the branching ratios and physical observables such as forward-backward asymmetries, lepton polarization asymmetries, form factor independent observables for $B_c\to D_s^{(*)} μ^+ μ^-$, both within the Standard Model and in new physics scenarios. Additionally, we examine the existence of lepton flavor universality violation in the $B_c\to D_s^{(*)} \ell^+ \ell^-$ process.

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arXiv2026

Exploring supernova neutrino mass ordering at DUNE via quantum entanglement

The Deep Underground Neutrino Experiment (DUNE) offers strong sensitivity to neutrinos from a Galactic core collapse supernova, providing a powerful probe of neutrino flavor conversion and the neutrino mass ordering. In this work, we study supernova neutrino oscillations at DUNE using quantum entanglement as an organizing framework. Treating the three flavor neutrino system as an effective multipartite quantum state, we quantify flavor correlations through the entanglement of formation, concurrence, and negativity, expressed directly in terms of flavor survival and transition probabilities. Benchmark scenarios defined by representative variations of the electron neutrino survival probability are constructed for each entanglement measure. Event rates and fluences are computed for a supernova at 10 kpc, and the mass ordering sensitivity is evaluated using detector-level simulations performed with the \texttt{SNOwGLoBES} framework, employing the Garching supernova flux model and including the dominant detection channels in liquid argon: $ν_e$ and $\barν_e$ charged-current interactions on argon and elastic scattering on electrons. We analyze both individual and combined detection channels and incorporate $5\%$ normalization and energy calibration systematic uncertainties. Our results show that DUNE achieves a $5σ$ determination of the neutrino mass ordering for a supernova at distances of $\sim 20$~kpc for the $ν_e$ charged current channel and $\sim 2$~kpc for the $\barν_e$ channel, with the reach depending on the entanglement scenario considered. These results demonstrate that entanglement based observables provide a complementary and robust framework for probing supernova neutrino oscillations and the neutrino mass ordering.

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arXiv2025

Binwise exploration of vector couplings in $B_s \to D_s^{(*)} τ\bar ν_τ$ decays

Recent results from the LHCb experiment have confirmed that lepton flavor universality is upheld in flavor-changing neutral current processes, such as $B \to K^{(*)} l^+ l^-$. However, discrepancies remain in the charged current sector, raising questions about the universality of lepton flavors in these processes. To explore this issue, we investigate the decays $B_s \to D_s^{(*)} τ\bar ν_τ$ in different $q^2$ bins, which involve the $b \to c τ\bar ν_τ$ transition. We employ a model-independent approach to analyze potential new physics by fitting both real and complex (axial)vector coefficients to the existing $b \to (u, c) τ\bar ν_τ$ data. Our analysis enables us to calculate the branching ratios and angular distributions for the $B_s \to D_s^{(*)} τ\bar ν_τ$ decays in four different $q^2$ bins. Additionally, we evaluate whether lepton flavor universality is maintained in these charged current decays or if deviations suggest the presence of new physics.

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arXiv2025

Revealing the $q^2$ dependence in $b \to s μ^+ μ^-$ baryonic decay modes

Measurements from the LHCb experiment and $B$ factories have revealed several discrepancies in angular observables of rare semileptonic $B$ decays involving the quark-level transition $b \to s \ell^+ \ell^-$. In this work, we conduct a model-independent comparative analysis of the rare semileptonic decays of baryons $Λ_b$, $Σ_b$ and $Ξ_b$, exploring various new physics scenarios. Our analysis includes predictions for branching ratios and angular observables, including forward-backward asymmetry, longitudinal polarization fractions, and lepton flavor universality ratios, both within the Standard Model and across six distinct new physics scenarios. Notably, we find that certain new physics scenarios significantly affect the observables in the $(Λ_b, Σ_b, Ξ_b) \to (Λ, Σ, Ξ) μ^+ μ^-$ processes.

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arXiv2025

Enhancing DUNE Physics Sensitivity with Light and Charge Calorimetry

We investigate the potential of light calorimetry in liquid argon time projection chambers and its intrinsic self compensation properties, emphasizing its advantages alongside conventional charge calorimetry. Previous studies have demonstrated that light calorimetry can achieve energy resolution comparable to advanced charge based techniques, particularly for GeV scale neutrinos. In this work, we explore the complementarity of light calorimetry with charge calorimetry for precision measurements of key physics parameters in the DUNE, including CP violation (CPV) and mass hierarchy determination. While charge calorimetry provides superior resolution in CP phase measurements, light calorimetry independently offers significant insights into CPV and mass hierarchy sensitivities. Furthermore, our exposure versus CPV sensitivity studies indicate that the $5σ$ discovery potential is reached faster using light and charge calorimetry than with the traditional TDR based reconstruction methods. These findings highlight the promising role of light calorimetry as a simple yet effective reconstruction method, serving as a complementary approach to enhance the physics capabilities of DUNE.

physics.ins-det↗

arXiv2024

Analysis of the semileptonic $B_c\to D_s^*μ^+ μ^-$ decay mode in the effective field theory approach

Discrepancies have been noted between experimental measurements and Standard Model predictions for various observables related to the $B\to(K, K^*,ϕ) ll$ processes. Recently, the Belle-II Collaboration observed a $2.8σ$ deviation from Standard Model predictions in the branching ratio of the $B \to K ν_l \bar{ν_l}$ decay mode. In this context, we investigate the exclusive semileptonic $B_c\to D_s^{*}μ^+ μ^-$ decay mode, mediated by $b\to s$ quark level transition, using Effective Field Theory formalism. We perform a global fit to the new parameters using existing experimental data on $b \to s μ^+ μ^-$. We then estimate the branching ratio and other observables such as forward-backward asymmetry, lepton polarisation asymmetry, and the lepton non-universality parameter of the $B_c\to D_s^{(*)}μ^+ μ^-$ process. Although this process has not yet been detected experimentally, we offer predictions and discuss the observables for $B_c\to D_s^{*}μ^+ μ^-$ in both the Standard Model and potential new physics scenarios.

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arXiv2024

GeV scale dark matter and $B\rightarrow K+$ missing energy phenomenology in the $U(1)_{B-L}$ model

We elucidate the recently observed discrepancy in the branching ratio of $B^{+}\rightarrow K^{+}$ +inv decay mode using a GeV scale scalar dark matter in an anomaly-free $U(1)_{B-L}$ gauge extension of the Standard Model. We constrain the new parameters by using consistency with the existing bounds on Dark matter relic density, direct detection, collider and BR($B\rightarrow K^*ν\barν$) measured at the Belle II experiment. We investigate couplings between the mediator and the SM fermions as well as the dark matter particle. We then estimate the branching ratios of $b \to s ν\bar ν$ decay processes such as $B\rightarrow (K^+,K^*)ν\barν$, $B_s\rightarrow (η,η')ν\barν$, $ B_s\rightarrow ϕν\barν$ and $B_c\rightarrow (D_s, D_s^*)ν\barν$ in a common parameter space, meeting the current experimental bounds of both sectors simultaneously.

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arXiv2022

Light dark matter, rare $B$ decays with missing energy in $L_μ-L_τ$ model with a scalar leptoquark

We investigate the phenomenology of light GeV-scale fermionic dark matter in $U(1)_{L_μ- L_τ}$ gauge extension of the Standard Model. Heavy neutral fermions alongside with a $S_1(\overline{3}$,$1$,$1/3$) scalar leptoquark and an inert scalar doublet are added to address the flavor anomalies and light neutrino mass respectively. The light gauge boson associated with $U(1)_{L_μ-L_τ}$ gauge group mediates dark to visible sector and helps to obtain the correct relic density. Aided with a colored scalar, we constrain the new model parameters by using the branching ratios of various $b \to sll$ and $b \to s γ$ decay processes as well as the lepton flavour non-universality observables $R_{K^{(*)}}$ and then show the implication on the branching ratios of some rare semileptonic $B \to (K^{(*)}, ϕ)+$ missing energy, processes.

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arXiv2021

Dark matter and flavor anomalies in the light of vector-like fermions and scalar leptoquark

We make a comprehensive study of vector-like fermionic dark matter and flavor anomalies in a simple extension of standard model. The model is added with doublet vector-like fermions of quark and lepton types, and also a $S_1(\bar{\textbf{3}},\textbf{1},1/3)$ scalar leptoquark. An additional lepton type singlet fermion is included, whose admixture with vector-like lepton doublet plays the role of dark matter and is examined in relic density and direct detection perspective. Electroweak precision observables are computed to put constraint on model parameter space. We constrain the new couplings from the branching ratios and angular observables associated with $b \to sll (ν_l \bar ν_l)$, $b \to s γ$ decays and also from the recent measurement on muon anomalous magnetic moment. We then estimate the branching ratios of the rare lepton flavor vioalting $B_{(s)}$ decay modes such as $B_{(s)} \to l_i^\mp l_j^\pm$, $B_{(s)} \to (K^{(*)}, ϕ) l_i^\mp l_j^\pm$.

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arXiv2021

$B_c \to D^{(*)}τ\bar ν_τ$ processes in an effective field theory approach

We present a compressive study on rare semileptonic $B_c \to D^{(*)}τ\bar ν_τ$ decays involving $b \to u τ\bar ν_τ$ quark level transitions in an effective field theory approach. We consider the presence of an additional (pseudo)vector and (pseudo)scalar type interactions which can be either complex or real and constrain the new couplings using the existing data on $R_{D^{(*)}}$, $R_{J/ψ}$, $R_π^l$, Br($B_{u,c} \to τ\bar ν_τ$) and Br($B \toπτ\bar ν_τ$) parameters. In order to segregate the sensitivity of new coefficients, we check the effects of these couplings on the branching ratios, lepton non-universality and various angular observables of $B_c \to D^{(*)}τ\bar ν_τ$ processes.

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arXiv2021

Scalar dark matter, Neutrino mass and Leptogenesis in a $\rm U(1)_{B-L}$ model

We investigate the phenomenology of singlet scalar dark matter in a simple $\rm U(1)_{B-L}$ gauge extension of standard model, made anomaly free with four exotic fermions. The enriched scalar sector and the new gauge boson $Z^\prime$, associated with $\rm U(1)$ gauge extension, connect the dark sector to the visible sector. We compute relic density, consistent with Planck limit and $Z^\prime$ mediated dark matter-nucleon cross section, compatible with PandaX bound. The mass of $Z^\prime$ and the corresponding gauge coupling are constrained from LEP-II and LHC dilepton searches. We also briefly scrutinize the tree level neutrino mass with dimension five operator. Furthermore, resonant leptogenesis phenomena is discussed with TeV scale exotic fermions to produce the observed baryon asymmetry of the Universe. Further, we briefly explain the impact of flavor in leptogenesis and we also project the combined constraints on Yukawa, consistent with oscillation data and observed baryon asymmetry. Additionally, we restrict the new gauge parameters by using the existing data on branching ratios of rare $B(τ)$ decay modes. We see that the constraints from dark sector are much more stringent from flavor sector.

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arXiv2020

Unified explanation of flavor anomalies, radiative neutrino mass and ANITA anomalous events in a vector leptoquark model

Driven by the recent experimental hints of lepton-flavor-universality violation in the bottom-quark sector, we consider a simple extension of the Standard Model (SM) with an additional vector leptoquark $V_{\rm LQ}({\bf 3},{\bf 1},2/3)$ and a scalar diquark $S_{\rm DQ}({\bf 6},{\bf 1},4/3)$ under the SM gauge group $SU(3)_c\times SU(2)_L\times U(1)_Y$, in order to simultaneously explain the $b \to s \ell^+ \ell^-$ (with $\ell=e,μ$) and $b \to c l^- \bar ν_l$ (with $l=e,μ,τ$) flavor anomalies, as well as to generate small neutrino masses through a two-loop radiative mechanism. We perform a global fit to all the relevant and up-to-date $b \to s \ell^+ \ell^-$ and $b \to c l^- \bar ν_l$ data under the assumption that the leptoquark couples predominantly to second and third-generation SM fermions. We then look over the implications of the allowed parameter space on lepton-flavor-violating $B$ and $τ$ decay modes, such as $B_s \to l^+_i l^-_j, \ B \to K^{(*)} l^+_i l^-_j, \ B_s \to ϕl^+_i l^-_j$, $Υ(nS) \to μτ$ and $τ\to μγ$, $τ\to μϕ(η^{(\prime)})$, respectively. Minimally extending this model by adding a fermion singlet $χ({\bf 1},{\bf 1},0)$ also explains the ANITA anomalous upgoing events. Furthermore, we provide complementary constraints on leptoquark and diquark couplings from high-energy collider and other low-energy experiments to test this model.

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arXiv2020

Efficacy of scalar leptoquark on $B_s \to (K^{()}, D_s^{()}) τ\bar ν_τ$ decay modes

We scrutinize the impact of various relevant scalar leptoquarks on the physical observables associated with the rare semileptonic decay processes of $B_s$ meson involving $b \to (u, c) l\bar ν_l$ quark level transitions. We constrain the new parameter space consistent with the experimental limit on Br($B_{u,c} \to τν_l$), Br($B \to πτ\bar ν_τ$), $R_{D^{(*)}}, R_{J/ψ}$ and $R_π^l$ observables. Using the allowed parameter space, we compute the branching ratios, forward-backward asymmetries, lepton and hardon polarization asymmetries of $B_s \to (K^{(*)}, D_s^{(*)}) τ\bar ν_τ$ decay modes. Forbye, we look at the possibility of existence of lepton non-universality in these processes.

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arXiv2019

Exploring Dark Matter, Neutrino mass and flavour anomalies in L_μ-L_τ model

We investigate Majorana dark matter in a new variant of $U(1)_{L_μ-L_τ}$ gauge extension of Standard Model, containing three additional neutral fermions $N_{e}, N_μ, N_τ$, along with a $(\bar{3},1,1/3)$ scalar Leptoquark (SLQ) and an inert doublet, to study the phenomenology of dark matter, neutrino mass generation and flavour anomalies on a single platform. The lightest mass eigenstate of the $N_μ, N_τ$ neutral fermions plays the role of dark matter. We compute the WIMP-nucleon cross section in leptoquark portal and the relic density mediated by inert doublet components, leptoquark and the new $Z^{\prime}$ boson. We constrain the parameter space consistent with Planck limit on relic density, PICO-60 and LUX bounds on spin-dependent direct detection cross section. We also discuss about the neutrino mass generation at one-loop level and the viable parameter region to explain current neutrino oscillation data. The $Z^\prime$ gauge boson of extended $U(1)$ symmetry and the SLQ play an important role in settling the known issues of flavor sector.

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arXiv2019

Investigating the role of new physics in $b \to c τ\bar ν_τ$ transitions

In recent times, the charged-current mediated semileptonic $b \to c τ\bar ν_τ$ processes have attracted a lot of attention after the observation of lepton non-universality ratios, $R_{D^{(*)}}$, $R_{J/ψ}$ and the measurements on $D^*$ and $τ$ longitudinal polarization fractions in $\bar B\to D^* τ\bar ν_τ$ processes. We present a model-independent analysis of $ \bar B\to D^{(*)} τ\bar ν_τ$, $ B_s\to D_s^{(*)} τ\bar ν_τ$, $ B_c^+ \to (η_c, J/ψ) τ^+ ν_τ$, $Λ_b \to Λ_c τ\bar ν_τ$ and $\bar B \to D^{**} τ\bar ν_τ$ (where $D^{**} = \{D^*_0, D_1^*, D_1, D_2^*\}$ are the four lightest excited charm mesons) processes involving $b \to c τ\bar ν$ quark level transitions by considering the most general effective Lagrangian in the presence of new physics. We perform a global fit to various set of new coefficients, including the measurements on $R_{D^{(*)}}$, $R_{J/ψ}$ and the upper limit on Br($B_c^+ \to τ^+ \bar ν_τ$). We then show the implications of constrained new couplings on the branching fractions, lepton non-universality ratios and various angular observables of these decay modes in four different bins of $q^2$.

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arXiv2019

Model independent analysis of $ B^* \to P \ell \barν_\ell$ decay processes

Very compelling deviations in the recently observed lepton nonuniversality observables $\big (R_{D^{(*)}}, R_{K^{(*)}}, R_{J/ψ} \big )$ of semileptonic $B$ meson decays from their Standard Model predictions hint towards the presence of some kind of new physics beyond it. In this regard, we investigate the effect of new physics in the semileptonic $\bar B_{d(s)}^* \to P \ell \barν_\ell$ decay processes, where $P=D,π(D_s,K$), in a model independent way. We consider the presence of additional vector and scalar type interactions and constrain the corresponding new couplings by fitting ${\rm Br(B_{u}^+ \to τ^+ ν_τ)}$, ${\rm Br(B \to πτ\bar ν_τ)}$, ${\rm Br(B_{c}^+ \to τ^+ ν_τ)}$, $R_π^l$, $R_{D^{(*)}}$ and $R_{J/ψ}$ data. Using the constrained new parameters, we estimate the branching ratios, forward-backward asymmetry, lepton-spin asymmetry and lepton non-universality observables of $\bar B_{d,s}^{*} \to P τ\bar ν_τ$ processes. We find that the branching ratios of these decay modes are sizeable and deviate significantly (for vector-type couplings) from their corresponding standard model values, which are expected to be within the reach of Run III of Large Hadron Collider experiment.

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arXiv2019

Exploring dark matter, neutrino mass and $R_{K^{(*)},ϕ}$ anomalies in $L_μ-L_τ$ model

We investigate Majorana dark matter in a new variant of $U(1)_{L_μ-L_τ}$ gauge extension of Standard Model, where the scalar sector is enriched with an inert doublet and a $(\bar{3},1,1/3)$ scalar leptoquark. We compute the WIMP-nucleon cross section in leptoquark portal and the relic density mediated by inert doublet components, leptoquark and the new $Z^{\prime}$ boson. We constrain the parameter space consistent with Planck limit on relic density, PICO-60 and LUX bounds on spin-dependent direct detection cross section. Furthermore, we constrain the new couplings from the present experimental data on ${\rm Br}(τ\to μν_τ\bar ν_μ)$, ${\rm Br}( B \to X_s γ)$, ${\rm Br}( B^0 \to K^0 μ^+ μ^-)$, ${\rm Br}(B^+ \to K^+ τ^+ τ^-)$ and $B_s-\bar{B_s}$ mixing, which occur at one-loop level in the presence of $Z^\prime$ and leptoquark. Using the allowed parameter space, we estimate the form factor independent $P_{4,5}^\prime$ observables and the lepton non-universality parameters $R_{K}$, $R_{K^*}$ and $R_ϕ$. We also briefly discuss about the neutrino mass generation at one-loop level and the viable parameter region to explain current neutrino oscillation data.

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arXiv2018

Probing new physics in semileptonic $Λ_b$ decays

In recent times, several hints of lepton non-universality have been observed in semileptonic $B$ meson decays, both in the charged-current ($b \to c l \bar ν_l$) and neutral-current ($b \to s ll $) transitions. Motivated by these intriguing results, we perform a model independent analysis of the semileptonic $Λ_b$ decays involving the quark level transitions $b \to (u,c) l ν_l$, in order to scrutinize the nature of new physics. We constrain the new parameter space by using the measured branching ratios of $B_{c, u}^+ \to τ^+ ν_τ$, $B \to πτν_τ$ processes and the existing experimental results on $R_{D^{(*)}}$, $R_{J/ψ}$ and $R_π^l$ parameters. Using the constrained parameters, we estimate the branching ratios, forward backward asymmetries, hadron and lepton polarization asymmetries of the $Λ_b \to (Λ_c, p) l ν_l$ processes. Moreover, we also examine whether there could be any lepton universality violation in these decay modes.

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