New Physics in b -> s mu+ mu-: CP-Conserving Observables

TL;DR

This paper investigates how different types of new physics operators affect various decay observables in b -> s mu+ mu- transitions, identifying which Lorentz structures can cause significant deviations from Standard Model predictions.

Contribution

It provides a comprehensive analysis of the impact of vector-axial vector, scalar-pseudoscalar, and tensor operators on decay observables, highlighting their potential to alter asymmetries and branching ratios.

Findings

VA operators can significantly enhance asymmetries beyond SM predictions.

SP and T operators mainly affect A_FB in B->K mu+ mu- decays.

Certain operators can cause observable deviations in decay distributions.

Abstract

We perform a comprehensive study of the impact of new-physics operators with different Lorentz structures on decays involving the b -> s mu+ mu- transition. We examine the effects of new vector-axial vector (VA), scalar-pseudoscalar (SP) and tensor (T) interactions on the differential branching ratios and forward-backward asymmetries (A_{FB}'s) of Bsbar -> mu+ mu-, Bdbar -> Xs mu+ mu-, Bsbar -> mu+ mu- gamma, Bdbar -> Kbar mu+ mu-, and Bdbar -> K* mu+ mu-, taking the new-physics couplings to be real. In Bdbar -> K* mu+ mu-, we further explore the polarization fraction f_L, the angular asymmetry A_T^{(2)}, and the longitudinal-transverse asymmetry A_{LT}. We identify the Lorentz structures that would significantly impact these observables, providing analytical arguments in terms of the contributions from the individual operators and their interference terms. In particular, we show that while the new VA operators can significantly enhance most of the asymmetries beyond the Standard Model predictions, the SP and T operators can do this only for A_{FB} in Bdbar -> Kbar mu+ mu-.