Angular analysis of the $B^{0}\rightarrow K^{*0}\mu^{+}\mu^{-}$ decay using $3\,\mbox{fb}^{-1}$ of integrated luminosity

TL;DR

This paper presents a detailed angular analysis of the $B^{0} ightarrow K^{*0} ightarrow K^{+}\pi^{-}\mu^{+}\mu^{-}$ decay using 3 fb$^{-1}$ of LHCb data, revealing potential deviations from Standard Model predictions.

Contribution

It introduces a comprehensive angular analysis method accounting for S-wave contamination and reports the first measurement of several angular observables and their zero-crossing points in this decay.

Findings

Observed deviations from Standard Model at 3.4 sigma level.

Measured angular observables and their correlations in multiple $q^2$ bins.

Identified potential signs of physics beyond the Standard Model or large hadronic effects.

Abstract

An angular analysis of the $B^{0}\rightarrow K^{*0}(\rightarrow K^{+}\pi^{-})\mu^{+}\mu^{-}$ decay is presented. The dataset corresponds to an integrated luminosity of $3.0\,{\mbox{fb}^{-1}}$ of $pp$ collision data collected at the LHCb experiment. The complete angular information from the decay is used to determine $C\!P$-averaged observables and $C\!P$ asymmetries, taking account of possible contamination from decays with the $K^{+}\pi^{-}$ system in an S-wave configuration. The angular observables and their correlations are reported in bins of $q^2$, the invariant mass squared of the dimuon system. The observables are determined both from an unbinned maximum likelihood fit and by using the principal moments of the angular distribution. In addition, by fitting for $q^2$-dependent decay amplitudes in the region $1.1<q^{2}<6.0\mathrm{\,Ge\kern -0.1em V}^{2}/c^{4}$, the zero-crossing points of several angular observables are computed. A global fit is performed to the complete set of $C\!P$-averaged observables obtained from the maximum likelihood fit. This fit indicates differences with predictions based on the Standard Model at the level of 3.4 standard deviations. These differences could be explained by contributions from physics beyond the Standard Model, or by an unexpectedly large hadronic effect that is not accounted for in the Standard Model predictions.