Lepton polarization in $B \to K_1 \ell^+ \ell^-$ Decays

TL;DR

This paper analyzes lepton polarization asymmetries in B meson decays to K1(1270) and leptons, revealing their potential to probe meson mixing angles and new physics effects.

Contribution

It provides a detailed study of lepton polarization asymmetries in B to K1(1270) l+ l- decays, highlighting their sensitivity to meson mixing and new physics.

Findings

Lepton polarization asymmetries depend strongly on dileptonic invariant mass.

Asymmetries can help determine the K1(1270)-K1(1400) mixing angle.

These asymmetries are more sensitive in B to K1(1270) l+ l- decays than in B to K* l+ l- decays.

Abstract

We study the single and double lepton polarization asymmetries in the semileptonic $B$ meson decays $B \to K_1 (1270) \ell^+ \ell^-$ $\ell \equiv e$, $\mu$, $\tau$), where the strange $P$-wave meson, $K_1(1270)$, is the mixtures of the $K_{1A}$ and $K_{1B}$, which are the $1^3P_1$ and $1^1P_1$ states, respectively. The lepton polarization asymmetries show relatively strong dependency in the various region of dileptonic invariant mass. The lepton polarization asymmetries can also be used for determining the $K_1(1270)$--$K_1(1400)$ mixing angle, $\theta_{K_1}$ and new physics effects. Furthermore, it is shown that these asymmetries in $B\to K_1(1270)\ell^+\ell^-$ decay compared with those of $B\to K^*\ell^+\ell^-$ decay are more sensitive to the dileptonic invariant mass.