Probing extended Higgs sector through rare b --> s mu+ mu- transitions

TL;DR

This paper investigates how rare B meson decays can reveal signs of an extended Higgs sector, focusing on muon asymmetries and their potential to distinguish new physics contributions.

Contribution

It provides new constraints on scalar and pseudoscalar operators affecting B decays and highlights the potential of muon polarization measurements to identify extended Higgs sectors.

Findings

Maximum <A_{FB}> is about 1%, making it hard to measure.

A_{LP} can reach 100% without conflicting with current bounds.

Muon polarization measurements can differentiate scalar and pseudoscalar new physics.

Abstract

We study the constraints on the contribution of new physics in the form of scalar/pseudoscalar operators to the average forward backward asymmetry <A_{FB}> of muons in B --> K mu+ mu- and the longitudinal polarization asymmetry A_{LP} of muons in B_s --> mu+ mu-. We find that the maximum possible value of <A_{FB}> allowed by the present upper bound on B(B_s --> mu+ mu-) is about 1% at 95% C.L. and hence will be very difficult to measure. On the other hand, the present bound on B(B_s --> mu+ mu-) fails to put any constraints on A_{LP}, which can be as high as 100% even if B(B_s --> mu+ mu-) is close to its standard model prediction. The measurement of A_{LP} will be a direct evidence for an extended Higgs sector, and combined with the branching ratio B(B_s --> mu+ mu-) it can even separate the new physics scalar and pseudoscalar contributions.