to A transition form factors and semileptonic decays in self-consistent covariant light-front approach

Avijit Hazra; S. Thejus Mary; Neelesh Sharma; Rohit Dhir

doi:10.1140/epjc/s10052-024-13249-9

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2024) 84: 944
https://doi.org/10.1140/epjc/s10052-024-13249-9

Regular Article - Theoretical Physics

$B_{c}$ $\varvec{B_c}$ to A transition form factors and semileptonic decays in self-consistent covariant light-front approach

Avijit Hazra¹, S. Thejus Mary¹, Neelesh Sharma² and Rohit Dhir¹^d

¹ Department of Physics and Nanotechnology, SRM Institute of Science and Technology, 603203, Kattankulathur, India
² Paradigm of Science Cultivation and Ingenious, 176032, Kangra, India

^d dhir.rohit@gmail.com

Received: 12 May 2024
Accepted: 16 August 2024
Published online: 18 September 2024

Abstract

We present a comprehensive analysis of the semileptonic weak decays of $B_{c}$ $$B_c$$ meson decaying to axial-vector (A) mesons for bottom-conserving and bottom-changing decay modes. We employ self-consistent covariant light-front quark model (CLF QM) that uses type-II correspondence to eliminate inconsistencies in the traditional type-I CLF QM. As a fresh attempt, we test the self-consistency in CLF QM through type-II correspondence for $B_{c} \to A$ $B_c \rightarrow A$ meson transition form factors. We establish that in type-II correspondence the form factors for longitudinal and transverse polarization states are numerically equal and are free from zero-mode contributions, which confirms the self-consistency of type-II correspondence for $B_{c} \to A$ $B_c \rightarrow A$ transition form factors. Furthermore, we ascertain that the problems of inconsistency and violation of covariance of CLF QM within the type-I correspondence are resolved in type-II correspondence for $B_{c} \to A$ $B_c \rightarrow A$ transitions. We thoroughly investigate the effects of self-consistency between type-I and type-II schemes using a comparative analysis. In this investigation, we employ a direct calculation approach to determine the form factors within the space-like region. Subsequently, we employ a vector meson dominance (VMD)-inspired three-parameter form to extrapolate these form factors into the physically accessible region. This enables us to study the $q^{2}$ $$q^2$$ dependence of the form factors in weak hadronic currents for the whole accessible kinematic range for both bottom-conserving as well as bottom-changing transitions. In addition, we extend our analysis to predict the branching ratios of the semileptonic weak decays of $B_{c}$ $$B_c$$ meson involving axial-vector meson in the final state to quantify the effects of self-consistency in these decays that were not studied before. We evaluate the lepton mass effect on these branching ratios and various other important physical observables, such as forward-backward asymmetries, lepton-side convexity parameter, asymmetry parameter, and longitudinal polarization asymmetries and fractions. Finally, we obtain the lepton flavor universality ratios for various decays.

© The Author(s) 2024

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