Exclusive $B \rar \rho \ell^+ \ell^-$ Decay in the Standard Model with Fourth--Generation

TL;DR

This paper studies how a hypothetical fourth generation of quarks could affect the decay process of B mesons into rho mesons and leptons, revealing potential signals of new physics beyond the Standard Model.

Contribution

It provides a detailed analysis of the impact of a fourth quark generation on B meson decay observables, including branching ratios and asymmetries, within the Standard Model framework.

Findings

Branching ratios increase with the fourth generation parameters.

CP-asymmetry and polarization asymmetries decrease due to the fourth generation.

Results suggest new physics effects could be detected via loop diagram signatures.

Abstract

We investigate the influence of the fourth generation of quarks on the branching ratio, the CP-asymmetry and the polarization asymmetries in $B \rar \rho \ell^+ \ell^-$ decay. Taking $|V_{t'd}V_{t'b}|\sim 0.001$ with phase about $10^\circ$, which is consistent with the $sin2\phi_1$ of the CKM and the $B_d$ mixing parameter $\Delta m_{B_d}$, we obtain that for both ($\mu, \tau$) channels the branching ratio is increased and the magnitude of CP-asymmetry and polarization asymmetries decreased by the mass and mixing parameters of the 4th generation of quarks . These results can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation of quarks($t', b')$ via its indirect manifestations in loop diagrams.