Angular analysis of the $B^{+}\rightarrow K^{\ast+}\mu^{+}\mu^{-}$ decay

TL;DR

This paper presents a comprehensive angular analysis of the $B^{+} ightarrow K^{ ext{*+}} ightarrow K_{S}^{0}\pi^{+}\mu^{+}\mu^{-}$ decay, measuring all CP-averaged observables across different invariant mass intervals, revealing deviations from Standard Model predictions.

Contribution

First measurement of the full set of CP-averaged angular observables in this decay mode across multiple mass intervals.

Findings

Observed local deviations from Standard Model predictions.

Detected global tension depending on effective couplings and nuisance parameters.

Results are consistent with previous anomalies in similar decay channels.

Abstract

We present an angular analysis of the $B^{+}\rightarrow K^{\ast+}(\rightarrow K_{S}^{0}\pi^{+})\mu^{+}\mu^{-}$ decay using 9$\,\mbox{fb}^{-1}$ of $pp$ collision data collected with the LHCb experiment. For the first time, the full set of CP-averaged angular observables is measured in intervals of the dimuon invariant mass squared. Local deviations from Standard Model predictions are observed, similar to those in previous LHCb analyses of the isospin-partner $B^{0}\rightarrow K^{\ast0}\mu^{+}\mu^{-}$ decay. The global tension is dependent on which effective couplings are considered and on the choice of theory nuisance parameters.