K_1(1270)-K_1(1400) mixing and the fourth generation SM effects in B-->K_1l^+l^- decays

TL;DR

This paper investigates how the presence of a hypothetical fourth generation of quarks could influence B meson decays into K_1 mesons and leptons, affecting measurable observables like branching ratios and asymmetries, which can be tested at LHC.

Contribution

It introduces the effects of a fourth quark generation on B-->K_1 l^+ l^- decays, analyzing various observables with specific mixing angles and form factors, providing predictions for experimental tests.

Findings

Branching ratio suppressed for K_1(1400) compared to K_1(1270).

Observables are highly sensitive to fourth generation effects.

Potential to detect fourth generation quarks through LHC measurements.

Abstract

The implications of the fourth generation quarks in the B-->K_{1}(1270,1400)l^{+}l^{-} with l=mu, tau decays are studied, where the mass eigenstates K_{1}(1270) and K_{1}(1400) are the mixture of ^{1}{P}_{1} and ^{3}{P}_{1} states with the mixing angle \theta_{K}. In this context, we have studied various observables like branching ratio (BR), forward backward asymmetry (A_{FB}) and longitudinal and transverse helicity fractions (f_{L,T}) of K_{1} meson in B-->K_{1}l^{+}l^{-} decays. To study these observables, we have used the Light Cone QCD sum rules form factors and set the mixing angle \theta_{K}=-34^{o}. It is noticed that the BR is suppressed for K_{1}(1400) as a final state meson compared to that of K_{1}(1270). Same is the case when the final state leptons are tauons rather than muons. In both the situations all the above mentioned observables are quite sensitive to the fourth generation effects. Hence the measurements of these observables at LHC, for the above mentioned processes can serve as a good tool to investigate the indirect searches for the existence of fourth generation quarks.