Symmetries in the angular distribution of exclusive semileptonic B decays

TL;DR

This paper explores symmetries in the angular distribution of exclusive B meson decays to develop observables that are less affected by QCD uncertainties, aiding the search for new physics.

Contribution

It introduces a method to construct QCD-uncertainty protected observables based on angular symmetries in B decay distributions, including the analysis of transverse asymmetries.

Findings

Transverse asymmetries AT^{(2)} and AT^{(5)} have distinct new physics sensitivities.

AT^{(2)} is shown to be an improved version of the forward-backward asymmetry.

The method provides a way to interpret angular distributions with reduced theoretical uncertainties.

Abstract

We discuss a method to construct observables protected against QCD uncertainties based on the angular distribution of the exclusive Bd -> K(*0}(-> Kpi) l+ l- decay. We focus on the identification and the interpretation of all the symmetries of the distribution. They constitute a key ingredient to construct a set of so-called transverse observables. We work in the framework of QCD factorization at NLO supplemented by an estimate of power-suppressed Lambda/mb corrections. A discussion of the new physics properties of two of the transverse asymmetries, AT^{(2)} and AT^{(5)}, is presented. A comparison between the transverse asymmetry AT^{(2)} and the forward-backward asymmetry shows that AT^{(2)} emerges as an improved version of it.