Implications of new physics in $B\to K_1{\mu }^{+}{\mu }^{-}$ decay processes

Abstract

In recent times, several discrepancies at the level of $(2-3)\sigma$ have been observed in the decay processes mediated by flavour changing neutral current (FCNC) transitions $b\to s{\ell }^{+}{\ell }^{-}$, which may be considered as the smoking-gun signal of New Physics (NP). These intriguing hints of NP have attracted a lot of attention and many attempts are made to look for the possible NP signature in other related processes, which are mediated through the same quark-level transitions. In this work, we perform a comprehensive analysis of the FCNC decays of $B$ meson to axial vector mesons $K_1(1270)$ and $K_1(1400)$, which are admixture of the $1^3{P}_1$ and $1^1{P}_1$ states $K_{1A}$ and $K_{1B}$, in a model independent framework. Using the $B\to K_1$ form factors evaluated in the light cone sum rule approach, we investigate the rare exclusive semileptonic decays $B\to K_1(1270){\mu }^{+}{\mu }^{-}$ and $B\to K_1(1400){\mu }^{+}{\mu }^{-}$. Considering all the possible relevant operators for $b\to s{\ell }^{+}{\ell }^{-}$ transitions, we study their effects on various observables such as branching fractions, lepton flavor universality violating ratio ($R_{K_1})$, forward-backward asymmetries, and lepton polarization asymmetries of these processes. These results will not only enhance the theoretical understanding of the mixing angle but also serve as a good tool for probing New Physics.

29 pages, 7 figures