Optimizing the basis of B->K*ll observables in the full kinematic range

TL;DR

This paper identifies an optimal set of observables for B->K*ll decays that minimizes theoretical uncertainties and enhances sensitivity to New Physics, providing Standard Model predictions and systematic error bounds.

Contribution

It introduces a basis of observables optimized for reduced form-factor dependence and improved New Physics sensitivity in B->K*ll decay analyses.

Findings

Proposed an optimal observable basis for B->K*ll decays.

Provided Standard Model predictions for these observables.

Established bounds on S-wave pollution from B->K_0*ll decay.

Abstract

We discuss the observables for the B->K*(->K pi)ll decay, focusing on both CP-averaged and CP-violating observables at large and low hadronic recoil with special emphasis on their low sensitivity to form-factor uncertainties. We identify an optimal basis of observables that balances theoretical and experimental advantages, which will guide the New Physics searches in the short term. We discuss some advantages of the observables in the basis, and in particular their improved sensitivity to New Physics compared to other observables. We present predictions within the Standard Model for the observables of interest, integrated over the appropriate bins including lepton mass corrections. Finally, we present bounds on the S-wave contribution to the distribution coming from the B->K_0*ll decay, which will help to establish the systematic error associated to this pollution.