arXiv subjects

Jignesh N. Pandya

Publications and source records attributed to Jignesh N. Pandya.

9 recordsLinked to original sources

arXiv2026

Detailed analysis of possible new-physics effects in the semileptonic decay $B_s \to D_s^{(*)}τ\barν$

We study the semileptonic decays $B_s \to D_s^{(*)}τ\barν$ as a promising probe for new physics (NP) beyond the standard model (SM). The extension of the SM is done through the introduction of four-fermion operators beyond the $V-A$ structure with the corresponding Wilson coefficients characterizing their contribution. The constraints on these coefficients are obtained from recent experimental data. Form factors describing hadron transitions are calculated in our covariant quark model with infrared confinement. Theoretical predictions for the full set of observables in these channels are provided. We analyze possible NP effects to be tested in future experiments.

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arXiv2024

Decay $B_c^+ \to D_{(s)}^{(*)+} \ell^+\ell^-$ within covariant confined quark model

We study the rare semileptonic decays of $B_c$ mesons within the effective field theoretical framework of covariant confined quark model. The transition form factors corresponding to $B_c^+ \to D^{(*)+}$ and $B_c^+ \to D_s^{(*)+}$ are computed in the entire $q^2$ range. Using form factors, we compute the branching fractions and compare them with the available theoretical results. We also compute various physical observables such as forward-backward asymmetry, longitudinal and transverse polarizations as well as clean angular observables.

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arXiv2023

Form factors and branching fraction calculations for $B_s \to D_s^{(*)} \ell^+ ν_\ell$ in view of LHCb observation

In light of the LHCb observations about the $B_s \to D_s^{(*)}\ell ν_\ell$ semileptonic decays, we study these channels within the Standard Model framework of covariant confined quark model. The necessary transition form factors are computed in the entire dynamical range of momentum transfer squared with built-in infrared confinement. Our computed ratios of the decay widths from tau mode to muon mode for $D_s$ and $D_s^*$ mesons are found to be $R(D_s) = 0.271 \pm 0.069$ and $R(D_s^*) = 0.240 \pm 0.038$. We further determine the ratio of the decay width from $D_s$ and $D_s^*$ channel for muon mode $Γ(B_s \to D_s μ^+ ν_μ)/Γ(B_s \to D_s^* μ^+ ν_μ) = 0.451 \pm 0.093$. Our results are in excellent agreement with the data from the latest LHCb experiments as well as lattice quantum chromodynamics simulations. We also compare the shape of differential decay distribution for $B_s \to D_s^* μ^+ ν_μ$ with the LHCb data and our results are in very good agreement throughout all the individual bins. Some other physical observables such as forward-backward asymmetry and longitudinal polarizations of leptons in the final state are also computed.

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arXiv2022

Spectroscopy of heavy-heavy flavour mesons and annihilation widths of quarkonia

Within the framework of nonrelativistic quark-antiquark Cornell potential model formalism, we study the annihilation of heavy quarkonia. We determine their annihilation widths resulting into digluon, dilepton, $3γ$, $3g$ and $γgg$ and compare our findings with the available theoretical results and experimental data. We also provide the charge radii and absolute square of radial Schrödinger wave function at zero quark-antiquark separation for heavy quarkonia and $B_c$ mesons.

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arXiv2021

Rare $b \to d$ decays in covariant confined quark model

In this article, we study the rare decays corresponding to $b \to d$ transition in the framework of the covariant confined quark model. The transition form factors for the channels $B^{+(0)} \to (π^{+(0)}, ρ^{+(0)},ω)$ and $B_s^0 \to K^{(*)0}$ are computed in the entire dynamical range of momentum transfer squared. Using the form factors, we compute the branching fractions of the rare decays and our results are found to be matching well with the experimental data. We also compute the ratios of the branching fractions of the $b \to s$ to $b \to d$ rare decays using the inputs from previous papers on $b \to s \ell^+\ell^-$ using this model. Further, using the form factors, model dependent and independent parameters, we also compute different other physical observables such as forward backward asymmetry, longitudinal polarization and angular observables in the entire $q^2$ range as well as in $q^2$ bins [0.1 -- 0.98] GeV$^2$ and [1.1 -- 6] GeV$^2$. We also compare our findings with different theoretical predictions.

hep-ph↗

arXiv2020

Bottomonium spectroscopy motivated by general features of pNRQCD

The bottomonium mass spectra is computed in the framework of potential non-relativistic quantum chromodynamics. The potential consists of a static term incorporating Coulombic plus confinement part along with a correction term added non-perturbatively from pNRQCD, which is classified in powers of the inverse of heavy quark mass \textit{O}$(1/m)$. The masses of excited bottomonia are calculated by perturbatively adding spin-hyperfine, spin-orbit and tensor components of one gluon exchange interactions in powers of \textit{O}$(1/m^2)$. Calculated masses are found to be consistent with other theoretical studies and experimental data. The Regge trajectories of the calculated mass spectra are also constructed. The values of the wave-functions are extracted and employed to calculate the electromagnetic transition widths and $γγ$, $e^+e^-$, light hadron and $γγγ$ decay widths of several states at various leading orders, within the non-relativistic QCD formalism. Some of the experimentally reported states of bottomonium family like $Υ$(10860), $Υ$(11020) and X(10610) are identified as mixed $S-D$ wave and $P$-wave states.

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arXiv2020

Semileptonic Decays of Charmed Mesons to Light Scalar Mesons

Within the framework of covariant confined quark model, we compute the transition form factors of $D$ and $D_s$ mesons decaying to light scalar mesons $f_0(980)$ and $a_0(980)$. The transition form factors are then utilized to compute the semileptonic branching fractions. We study the channels namely, $D_{(s)}^+ \to f_0(980) \ell^+ ν_\ell$ and $D \to a_0(980) \ell^+ ν_\ell$ for $\ell = e$ and $μ$. For computation of semileptonic branching fractions, we consider the $a_0(980)$ meson to be the conventional quark-antiquark structure and the $f_0(980)$ meson as the admixture of $s\bar{s}$ and light quark-antiquark pairs. Our findings are found to support the recent BESIII data.

hep-ph↗

arXiv2019

Exclusive semileptonic decays of $D$ and $D_s$ mesons in the covariant confining quark model

Recently, the BESIII collaboration has reported numerous measurements of various $D_{(s)}$ meson semileptonic decays with significantly improved precision. Together with similar studies carried out at BABAR, Belle, and CLEO, new windows to a better understanding of weak and strong interactions in the charm sector have been opened. In light of new experimental data, we review the theoretical description and predictions for the semileptonic decays of $D_{(s)}$ to a pseudoscalar or a vector meson. This review is essentially an extended discussion of our recently published results obtained in the framework of the covariant confining quark model.

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arXiv2019

Semileptonic $D_{(s)}$-meson decays in the light of recent data

Inspired by recent improved measurements of charm semileptonic decays at BESIII, we study a large set of $D(D_s)$-meson semileptonic decays where the hadron in the final state is one of $D^0$, $ρ$, $ω$, $η^{(\prime)}$ in the case of $D^+$ decays, and $D^0$, $ϕ$, $K^0$, $K^\ast(892)^0$, $η^{(\prime)}$ in the case of $D^+_s$ decays. The required hadronic form factors are computed in the full kinematical range of momentum transfer by employing the covariant confined quark model developed by us. A detailed comparison of the form factors with those from other approaches is provided. We calculate the decay branching fractions and their ratios, which show good agreement with available experimental data. We also give predictions for the forward-backward asymmetry and the longitudinal and transverse polarizations of the charged lepton in the final state.

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