arXiv subjects

Kalpalata Dash

Publications and source records attributed to Kalpalata Dash.

3 recordsLinked to original sources

arXiv2024

Exclusive rare semileptonic decays of $B$ and $B_c$ mesons in the relativistic independent quark model

We investigate the exclusive rare semileptonic decays: $B(B_c)\to K(D_{(s)})l\bar{l}/\Sigma\nu_l\bar{\nu_l}$ ($l=\mu, \tau$) in the framework of relativistic independent quark (RIQ) model based on an average flavor independent confining potential in equally mixed scalar-vector harmonic form. The invariant weak form factors, parametrising the matrix elements between participating meson states are calculated in the parent meson rest frame. The momentum transfer dependence of the form factors is reliably determined in the whole accessible kinematical range: $q^2_{min}\leq 0\leq q^2_{max}$. Our predicted branching fractions for $B\to K\mu^+\mu^-/\tau^+\tau^-(\Sigma\nu_l\bar{\nu_l})$, $B_c\to D(D_s)\mu^+\mu^-$, $B_c\to D(D_s)\tau^+\tau^-$ and $B_c\to D(D_s)\Sigma\nu_l\bar{\nu_l}$, obtained in order of $10^{-7}(10^{-6})$, $10^{-9}(10^{-7})$, $10^{-9}(10^{-8})$ and $10^{-8}(10^{-7})$, respectively are in reasonable agreement with other Standard Model predictions and Lattice QCD results. The averaged values of the lepton polarization asymmetries for decay modes are obtained as $\langle P_L(B\to K\mu^+\mu^-)\rangle$=-0.97, $\langle P_L(B_c\to D_{(s)}\mu^+\mu^-)\rangle$=-0.972, $\langle P_L(B\to K\tau^+\tau^-)\rangle$=-0.224, $\langle P_L(B_c\to D\tau^+\tau^-)\rangle$=-0.275 and $\langle P_L(B_c\to D_s\tau^+\tau^-)\rangle$=-0.194.

hep-ph↗

arXiv2023

Purely leptonic decays of heavy-flavored charged mesons

We study the purely leptonic decays of heavy-flavored charged pseudoscalar (P) and vector (V) mesons ($D_{(s)}^{(*)+}$, $B_{(c)}^{(*)+}$) in the relativistic independent quark (RIQ) model based on an average flavor-independent confining potential in equally mixed scalar-vector harmonic form. We first compute the mass spectra of the ground-state-mesons and fix the model parameters necessary for the present analysis. Using the meson wave functions derivable in the RIQ model, and model parameters so fixed from hadron spectroscopy, we predict the decay constants: $f_{P(V)}$, ratios of decay constants: $f_{V}/f_{P}$, $f_{P_1}/f_{P_2}$, $f_{V_1}/f_{V_2}$, and the branching fractions (BFs): ${\cal B}(P(V)\to l^+\nu_l)$, $l=e, \mu, \tau$, which agree with the available experimental data and other Standard Model (SM) predictions. For the unmeasured decay constants especially in the purely leptonic decays of the charged vector mesons, our predictions could be tested in the upcoming Belle-II, SCTF, CEPC, FCC-ee and LHCb experiments in near future.

hep-ph↗

arXiv2023

The nonleptonic decays of $b$-flavored mesons to $S$-wave charmonium and charm meson states

The detection of radially excited heavy meson \\states in recent years and measurement of heavy meson decays, particularly $B_c^+\to J/ψD_s^+$ and $B_c^+\to J/ψD_s^{*+}$, by the LHCb and ATLAS Collaborations, have aroused a lot of theoretical interest in the nonleptonic decays of $b$-flavored mesons. In this paper, we study the exclusive two-body nonleptonic $\bar{B}^0$, $\bar{B_s^0}$, $B^-$ and $B_c^-$-meson decays to two vector meson ($V_1(nS)V_2$) states. Assuming the factorization hypothesis, we calculate the weak-decay form factors from the overlapping integrals of meson wave functions, in the framework of the relativistic independent quark (RIQ) model. We find a few dominant decay modes: $B^-\to D^{*0}ρ^-$, $\bar{B^0}\to D^{*+}ρ^-$, $\bar{B_s^0}\to D_s^{*+}ρ^-$, $B^-\to J/ψK^{*-}$ and $B_c^-\to J/ψD_s^{*-}$ with predicted branching fractions of 1.54, 1.42, 1.17, 0.53 and 0.52 (in $\%$), which are experimentally accessible. The predicted branching fractions for corresponding decay modes to excited ($2S$) states, obtained in the order ${\cal O }(10^{-3}-10^{-4})$ lie within the detection accuracy of the current experiments at LHCb and Tevatron. The sizeable $CP$-odd fractions predicted for $B_c^-$-meson decay to two charmful states: $D^{*0}D^{*-}_{(s)}$ and $\bar{D}^{*0}D^{*-}_{(s)}$ indicate significant $CP$-violation hinting at the so-called new physics beyond the standard model.

hep-ph↗