Complete Anatomy of B -> K*ll and its angular distribution

TL;DR

This paper develops a comprehensive set of optimal observables for the B -> K* l+l- decay, enabling maximal extraction of angular distribution information and sensitivity to new physics in a systematic and model-independent way.

Contribution

It introduces a complete basis of observables for the decay, expressing all measurable quantities in terms of this set, including symmetries and extensions to large-q^2 regions.

Findings

Provides explicit expressions for angular distributions.

Shows sensitivity to right-handed currents and scalars.

Identifies symmetries of the full distribution.

Abstract

We present a complete and optimal set of observables for the exclusive 4-body B meson decay B -> K*(->K pi) l+l- in the low dilepton mass region, that contains a maximal number of clean observables. This basis of observables is built in a systematic way. We show that all the previously defined observables and any observable that one can construct, can be expressed as a function of this basis. This set of observables contains all the information that can be extracted from the angular distribution in the cleanest possible way. We provide explicit expressions for the full and the uniangular distributions in terms of this basis. The conclusions presented here can be easily extended to the large-q^2 region. We study the sensitivity of the observables to right-handed currents and scalars. Finally, we present for the first time all the symmetries of the full distribution including massive terms and scalar contributions.