Eur. Phys. J. Spec. Top. (2024) 233: 2087-2100
https://doi.org/10.1140/epjs/s11734-024-01239-7

Regular Article

Assessing lepton flavor universality violations in semileptonic decays

¹ School of Physical Sciences, National Institute of Science Education and Research, An OCC of Homi Bhabha National Institute, 752050, Jatni, Odisha, India
² Department of Physics and Astronomy, Center for Nuclear Theory, Stony Brook University, 11794-3800, Stony Brook, New York, USA

^c rajeevofficial24@gmail.com

Received: 14 August 2023
Accepted: 28 June 2024
Published online: 12 July 2024

Abstract

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, $b\to cl{\nu }_l$ and $b\to s{l}^{+}{l}^{-}$. We provide predictions for lepton flavor violating observables, ${\mathcal{R}}_{J/\psi }$ and ${\mathcal{R}}_{{\eta }_c}$, 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 ${\mathcal{R}}_{D(D^{\ast })}$ and ${\mathcal{R}}_{K(K^{\ast })}$ 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.