Analysis of $\it{\Lambda}^\mathrm{0}_b \rightarrow pK^-\mu^+\mu^-$ decays

TL;DR

This paper measures the differential branching fraction and angular coefficients of the decay $ ext{ extLambda}_b^0 ightarrow pK^-\mu^+\mu^-$ using LHCb data, revealing interference patterns indicative of flavor-changing neutral currents.

Contribution

First measurement of angular coefficients and differential branching fractions for this decay mode using a large LHCb dataset.

Findings

Data consistent with multiple $ ext{ extLambda}$ resonances with different quantum numbers.

Angular coefficients exhibit vector-axial vector interference patterns.

Results support the presence of flavor-changing neutral-current processes.

Abstract

The differential branching fraction and angular coefficients of $\it{\Lambda}^\mathrm{0}_b \rightarrow pK^-\mu^+\mu^-$ decays are measured in bins of the dimuon mass squared and dihadron mass. The analysis is performed using a data set corresponding to 9$\text{fb}^{-1}$ of integrated luminosity collected with the $\mbox{LHCb}$ detector between 2011 and 2018. The data are consistent with receiving contributions from a mixture of $\it{\Lambda}$ resonances with different spin-parity quantum numbers. The angular coefficients show a pattern of vector-axial vector interference that is a characteristic of the type of flavour-changing neutral-current transition relevant for these decays.