arXiv subjects

Sonali Patnaik

Publications and source records attributed to Sonali Patnaik.

12 recordsLinked to original sources

arXiv2025

A comprehensive study of $B$, $B_s$ and $B_c$ meson semitauonic modes in potential quark model

In this work, we derive the form factors and compute the branching fractions for the semitauonic decay modes, $B \to D^{(*)}\,τ\,ν_τ$, $B_s \to D_s^{(*)}\,τ\,ν_τ$, $B_c \to η_c\,(J/ψ)\,τ\,ν_τ$, and $B_c \to D^{(*)}\,τ\,ν_τ$ within the \emph{Relativistic Independent Quark (RIQ) Model}, emphasizing a quark potential model based analysis of these transitions. We outline the essential elements of the model, incorporating corrections from residual interactions and center-of-mass motion, and perform a comprehensive study of the form factors across the full physical kinematic range of $q^2$. The resulting predictions demonstrate consistency and good agreement with existing theoretical approaches and experimental measurements. Motivated by recent observations of polarization observables at LHCb and Belle, we further evaluate these quantities within our framework and find results compatible with Standard Model (SM) expectations. The predictions presented here serve as theoretical input in decay channels for which Lattice QCD results remain limited, offering guidance for future experimental and Lattice efforts. Thus, semileptonic $B$ decays continue to serve as precise and discerning probes of the fundamental mechanisms governing flavor transitions in the SM.

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arXiv2025

$B \to D^{(*)} τν_τ$ decay properties with RIQ model

In this work we compute the branching fraction of $B \to D^{(*)} \,τ\, ν_τ$ and $B_s \to D_s^{(*)}\, τ\, ν_τ$ within the Relativistic Independent Quark Model, emphasizing the harmonic potential model dependent analysis of these decay channels in the precision flavor physics era. Considering the experimental observation of longitudinal $τ$-polarization and fraction of longitudinal polarization at LHCb and Belle, we have also investigated these observables within our model framework which are aligning well with the standard model expectations. We perform a comprehensive analysis of the form factors across the whole accessible kinematic range of $q^2$. Our results are consistent and compatible with other theoretical approaches as well as with the experimental measurements. Furthermore, we evaluated the clean ratios of $B_s$ to $B_0$ in the semimuonic mode that are in accordance with the LHCb measurements, and support the validity of the SU(3) flavor symmetry. Although the concept of new physics is facing a significant challenge at the current TeV scale, semileptonic $B$ decays, nevertheless, always serve as a valuable probe to study the decay dynamics.

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arXiv2025

Mass spectrum of S-wave mesons in the relativistic independent quark model

The confining strength or model parameters and constituent quark masses are reparametrized for predicting the ground state meson masses. We analyzed these from the hyperfine splitting of $S$-wave heavy-flavored, heavy-light and light (except non-strange) mesons in the framework of a relativistic independent quark (RIQ) model with one gluon exchange and centre-of-mass correction. These mesons with spin parity $J^P=0^-$ and $1^-$, the masses obtained are in accordance with the experimental physical masses. The results will serve as good complementary tools in further study of hadron dynamics and will behave as a foundation for the higher excited and exotic states of hadrons.

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arXiv2024

Unravelling theoretical challenges in understanding $B_c$ meson decay

The $B_c$ meson, a unique bound state comprising of two open heavy flavors, charm and bottom, offers a rich avenue for probing the predictions of the Next Decade - Standard Model (ND-SM) physics properties due to its heavy mass. With recent observations of its excited states, interest in understanding $B_c$ production mechanisms and decay modes has surged. This article presents the current state of art on $B_c$ mesons, encompassing production mechanisms, properties of different decay modes, and theoretical modeling. We present novel findings on the newly constructed ratios $(\mathcal{R}_{η_c/J/ψ}$, $\mathcal{R}_{D/D^*})$ in semileptonic and ($\mathcal{R}_μ^τ)^{B_c}$ , ($\mathcal{R}_μ^τ)^{B_c^*}$ in leptonic decays, respectively. These results emphasize the importance of $B_c$ studies in the future collider experiments. The article further explores CP effects in $B_c$ meson decays refining our understanding of heavy flavor properties. Finally, potential avenues for future research, and leveraging upcoming collider experiments are outlined.

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arXiv2024

Study of angular observables in exclusive semileptonic $B_c$ decays

In this work, we investigate angular observables such as the longitudinal polarization of charged leptons, $τ$-polarization, and forward-backward asymmetry in semileptonic $B_c$ decays. Additionally, we provide predictions for lepton flavor violating observables, the $\mathcal{R}$ ratios in the decay channels $B_c \rightarrow η_c (J/ψ) l ν_l$ and $B_c \rightarrow D (D^*) l ν_l$ across the entire $q^2$ region. Our analysis is conducted within the Relativistic Independent Quark Model, focusing on the potential model-dependent aspects of these observables. We compare our model predictions with existing lattice predictions, highlighting the strong applicability of our framework in describing $B_c$ decays. Considering the forthcoming experimental upgrades and the Run 3 data results on $B_c$ meson decays, rapid confirmation of these quantities could indicate significant discoveries of physics beyond the Standard Model. This will open up new avenues for understanding the complex flavor dynamics in heavy meson decays.

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arXiv2024

Study of exclusive decays of \texorpdfstring{$B_s \to ψ(1S,2S) K_s$}{Lg} and \texorpdfstring{$B_s \to η_c(1S,2S) K_s$}{Lg}

We analyze the exclusive two-body nonleptonic decays of $B_s$ meson to ground as well as radially excited $2S$ charmonium state with a light meson $K_s$, induced by the $b\to c\bar{c}d$ transition. Within the framework of relativistic independent quark (RIQ) model based on a flavor-independent interaction potential in scalar-vector harmonic form, we calculate the weak form factors from the overlapping integrals of meson wave function obtained in this model. Using the factorization approximation, we predict the branching fractions for the $B_s \to ψ(1S,2S) K_s$ and $B_s \to η_c(1S,2S) K_s$, which can be compared with future theoretical predictions. Branching fraction for $B_s\to J/ψK_s$ decay is found to be in good agreement with the data from LHCb Collaboration, whereas for $B_s\to ψ(2S) K_s$, it is found to be within the detection ability of the CMS Collaboration. We also predict the ratios of branching fractions $(\cal{R})$, which are in broad agreement with the data from LHCb Collaboration. These results indicate that the present approach works well in the description of exclusive nonleptonic $B_s$ decays within the framework of the RIQ model.

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arXiv2024

Assessing Lepton Flavor Universality Violations in Semileptonic Decays

In light of recent measurements suggesting potential lepton flavor universality violations in semileptonic decays at collider experiments, this article provides a concise study of tree- and loop-level $B$-hadron semileptonic decays, $b \to c l ν_l$ and $b \to s l^+ l^-$. We provide predictions for lepton flavor violating observables, $\mathcal{R}_{J/ψ}$ and $\mathcal{R}_{η_c}$, across the entire $q^2$ range. Our study employs the Relativistic Independent Quark Model (RIQM), highlighting a model-dependent approach to these observables. We compare our model's predictions with existing lattice predictions, demonstrating the strong applicability of the RIQM framework in describing $B_c$ decays. Additionally, we reassess global averages for $\mathcal{R}_{D(D^*)}$ and $\mathcal{R}_{K(K^*)}$ in semileptonic transitions. With the upcoming experimental upgrades and the anticipated Run 3 data on $B_c$ meson decays, rapid confirmation of these quantities could indicate significant evidence of physics beyond the Standard Model, thereby opening new pathways for understanding the complex flavor dynamics in $B$ meson decays.

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arXiv2023

A Light shed on Lepton Flavor Universality in B decays

At the back of succeeding measurements of anomalies in semileptonic decays at LHCb and several collider experiments hinting at the possible violation of lepton flavor universality, we undertake a concise review of theoretical foundations of the tree- and loop-level $b$-hadron decays, $b \to c l ν_l$ and $b \to s l^+ l^-$ along with experimental environments. We revisit the world averages for $R_{D(D^*)}$, $R_{K(K^*)}$, $R_{J/ψ}$, and $R_{η_c}$, for the semileptonic transitions and provide results within the framework of the relativistic independent quark model in addition to the results from model-independent studies. If the ongoing evaluation of the data of LHC Run 2 confirms the measurements of Run 1, then the statistical significance of the effect in each decay channel is likely to reach 5~$σ$. A confirmation of these measurements would soon turn out to be the first remarkable observation of physics beyond the Standard Model providing a wider outlook on the understanding of New Physics.

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arXiv2021

Lepton mass effects in exclusive semileptonic $B_c$-meson decays

In this work, we discuss exclusive semileptonic $B_c$-meson decays: $B_c\to η_c(J/ψ)lν$ and $B_c\to D(D^*)lν$ in the framework of the relativistic independent quark(RIQ) model based on an average flavor independent confining potential in equally mixed scalar-vector harmonic form. We calculate the invariant form factors representing decay amplitudes from the overlapping integrals of meson wave functions derivable in the RIQ model. To evaluate the lepton mass effects in the semileptonic decays, we first study the $q^2$-dependence of the form factors in the accessible kinematic range of $q^2$ involved in the decay process in its $e^-$ and $τ^-$ mode separately. Similar studies on helicity amplitudes, $q^2-$spectra for different helicity contributions, and total $q^2$-spectra for each decay process are carried out separately in their $e^-$ and $τ^-$ modes. We predict the decay rates/ branching fractions, forward-backward asymmetry, and the asymmetry parameter in reasonable agreement with other model predictions, which can hopefully be tested in future experiments at the Tevatron and LHC. We also predict the observable $'R'$ which corresponds to the ratio of branching fractions for the decay process in its $e^-$ mode to its corresponding value in the $τ^-$ mode. Our results are comparable to another standard model(SM) predictions which highlight the failure of the lepton flavor universality hinting at new physics beyond SM for the explanation of the observed deviation of observable $'R'$ value from the corresponding SM predictions.

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arXiv2019

Semileptonic $B_c$ meson decays to S-wave charmonium states

We study the semileptonic decays of $B_c$ meson to S-wave charmonium states in the framework of relativistic independent quark model based on an average flavor-independent confining potential $U(r)$ in the scalar-vector harmonic form $U(r)=\frac{1}{2}(1+γ^0)(ar^2+V_0)$, where ($a$, $V_0$) are the potential parameters.The form factors for $B_c^+\to η_c /ψe^+ν_e$ transitions are studied in the physical kinematic range. Our predicted branching ratios (BR) for transitions to ground state charmonia are found comparatively large $\sim $ $10^{-2}$, compared to those for transitions to radially excited 2S and 3S states. Like all other mpdel predictions, our predicted BR are obtained in the hierarchy: BR($B_c^+\to η_c /ψ(3S)$) $<$ BR($B_c^+\to η_c/ ψ(2S)$) $<$ BR($B_c^+\to η_c /ψ(1S)$). The longitudinal ($Γ_L$) and transverse polarization ($Γ_T$) for $B_c \to ψ(ns)$ decay modes are predicted in the small and large $q^2$ - region as well as in the whole physical region. The ratios for such transitions are obtained $\frac {Γ_L}{Γ_T} < 1$ throughout the kinematic range which means the $B_c^+$ meson transitions to vector meson charmonium states take place predominantly in transverse polarization mode. The theoretical predictions on these transitions could be tested in the on-going and forthcoming experiments at LHCb.

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arXiv2018

Electromagnetic transitions of $(b{\bar c})$ bound system

We study electromagnetic transitions: $B_c^*(ns)\to B_c(ns) e^+ e^-$, $B_c^*(ns)\to B_c(n^{\prime}s) e^+ e^-$ and $B_c(ns)\to B^*_c(n^{\prime}s) e^+ e^-$ in the relativistic independent quark (RIQ) model based on a flavor-independent potential in the scalar-vector harmonic form. The transition form factors for energetically possible transitions involving $B_c$ - and $B_c^*$- mesons in ground as well as orbitally excited states are predicted in their respective kinematic range. Our predictions on decay width for the allowed and hindered transitions are found compatible with those of the model calculations based on Bethe-Salpeter approach. Predictions in this sector would not only provide more information about members of the $B_c$-family including mass splitting between vector mesons and corresponding pseudoscalar counterparts but give hints for experimental determination of unknown masses of other excited $B_c$ - and ground state of $B_c^*$-meson, which is expected at LHCb and $Z^0$ factory in near future.

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arXiv2017

Magnetic Dipole Transitions of $B_c$ and $B_c^*$ mesons in the Relativistic Independent Quark Model

We study M1-transitions involving mesons: $B_c(1s)$, $B_c^*(1s)$, $B_c(2s)$, $B_c^*(2s)$, $B_c(3s)$ and $B_c^*(3s)$ in the relativistic independent quark (RIQ) model based on a flavor independent average potential in the scalar-vector harmonic form. The transition form factor for $B_c^*\to B_cγ$ is found to have analytical continuation from spacelike to physical timelike region. Our predicted coupling constant $g_{B_c^* B_c}$ = 0.34 Ge$V^{-1}$ and decay width $Γ(B_c^*\to B_cγ)$ = 23 eV agree with other model predictions. In view of possible observation of $B_c$ and $B_c^*$ s-wave states at LHC and Z-factory and potential use of theoretical estimate on M1-transitions, we investigate the allowed as well as hindered transitions of orbitally excited $B_c$-meson states and predict their decay widths in overall agreement with other model predictions. We consider the typical case of $B_c^*(1s)\to B_c(1s)γ$, where our predicted decay width which is found quite sensitive to the mass difference between $B_c^*$ and $B_c$ mesons may help in determining the mass of $B_c^*$ experimentally.

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