K1(1270)-K1(1400) Mixing Angle and New-Physics Effects in B to K1 l+ l- Decays

TL;DR

This paper analyzes B meson decays to K1(1270) and K1(1400) to determine their mixing angle and explores how new physics could alter decay asymmetries and observables, providing insights into potential physics beyond the Standard Model.

Contribution

It introduces a method using decay ratios to determine the K1 mixing angle and studies the impact of new physics on decay asymmetries and zero-crossing points.

Findings

The ratio R_l is effective for determining the K1 mixing angle.

Forward-backward asymmetry zero position is sensitive to new physics.

Decay observables can reveal new-physics effects in b to s l+ l- transitions.

Abstract

We study semileptonic B meson decays B to K_1(1270) l^+ l^- and K_1(1400) l^+ l^- (l=e, mu, tau), where the strange P-wave mesons, K_1(1270) and K_1(1400), are the mixtures of the K_{1A} and K_{1B}, which are the 1^3P_1 and 1^1P_1 states, respectively. We show that the ratio R_l = Br(B to K_1(1400) l^+ l^-)/Br(B to K_1(1270) l^+ l^-), insensitive to new-physics parameters, is suitable for determining the K_1(1270)-K_1(1400) mixing angle, theta_{K_1}. The forward-backward asymmetry shows a weak theta_{K_1}-dependence for B to K_1(1270) mu^+ mu^-, but relatively strong for B to K_1(1400) mu^+ mu^-. We investigate model-independent new-physics corrections to operators relevant to the b to s l^+ l^- electroweak-penguin and weak-box diagrams. Furthermore, for the B to K_1(1270) mu^+ mu^- decay the position of the forward-backward asymmetry zero, which is almost independent of the value of theta_{K_1}, can be dramatically changed under variation of new-physics parameters.