XXVI DAE-BRNS High Energy Physics Symposium 2024

Study on Bc→J/ψ(ηc) and Bc→χc0,1(hc) semileptonic channels in modified perturbative-QCD framework

Not scheduled

20m

Swatantrata Bhavan, Banaras Hindu University, Varanasi

Oral Quark and lepton flavour physics

Speaker

UTSAB DEY (INDIAN INSTITUTE OF TECHNOLOGY, GUWAHATI)

Description

This study investigates the decay modes of the $B_c$ meson, focussing on semileptonic decays into S and P wave charmonia. The primary objective is to extract the shape parameter of the $B_c$ meson distribution amplitude through a data-driven approach, utilizing $B_c\to {\eta }_c,J/\psi$ form factors in modified perturbative QCD framework. Further, by employing heavy quark spin symmetry, shape of $B_c\to {\eta }_c$ form factor is derived from existing lattice results of $B_c\to J/\psi$ form factors, giving a model-independent prediction of LFUV observable $R({\eta }_c)=0.304(36)$, which we have found to be in good agreement with previous results. Additionally, we have extracted the decay constants of $P$ wave charmonium states, ${\chi }_{c0}$, ${\chi }_{c1}$ and $h_c$ through their radiative decay modes, providing a data-driven alternative to existing model dependent values, enabling us to use them as inputs to predict the $B_c\to P$ wave form factors at $q^2=0$ within the modified perturbative QCD framework. Subsequently, utilizing the shapes of the $B_c\to {\eta }_c$ and $J/\psi$ form factors, we have obtained $q^2$ distribution of the $B_c\to {\chi }_{c0},{\chi }_{c1}$ and $h_c$ form factors through pole expansion parametrization, using which we obtain predictions of LFUV observables $R({\chi }_{c0})=0.195(4)$, $R({\chi }_{c1})=0.129(7)$ and $R(h_c)=0.109(4)$.