Differential branching fraction and angular analysis of the decay $\boldsymbol{B^{0} \rightarrow K^{*0} \mu^+ \mu^-}$

TL;DR

This paper presents a precise measurement of angular distributions and partial branching fractions in the decay B0 to K*0 mu+ mu-, testing Standard Model predictions with data from the LHCb detector.

Contribution

It provides the most precise measurements to date of angular observables and branching fractions for B0 to K*0 mu+ mu- decay, consistent with the Standard Model.

Findings

Measurements agree with Standard Model predictions.

Results are the most precise to date.

Specific values: A_FB=-0.06, F_L=0.55, dB/dq^2=0.42e-7 in the specified q^2 range.

Abstract

The angular distributions and the partial branching fraction of the decay $B^{0} \rightarrow K^{*0} \mu^+ \mu^-$ are studied using an integrated luminosity of $0.37\,fb^{-1}$ of data collected with the LHCb detector. The forward-backward asymmetry of the muons, $A_{\mathrm{FB}}$, the fraction of longitudinal polarisation, $F_{\mathrm{L}}$, and the partial branching fraction, $\mathrm{d}{\mathcal B}/\mathrm{d}q^{2}$, are determined as a function of the dimuon invariant mass. The measurements are in good agreement with the Standard Model predictions and are the most precise to date. In the dimuon invariant mass squared range $1.00-6.00{\mathrm{\,Ge\kern -0.1em V}}^2/c^4$, the results are $A_{\mathrm{FB}}=-0.06\,^{+0.13}_{-0.14} \pm 0.04$, $F_{\mathrm{L}}=0.55\pm 0.10\pm 0.03$ and $\mathrm{d}{\mathcal B}/\mathrm{d}q^{2}=(0.42 \pm 0.06\pm 0.03) \times 10^{-7}c^4/{\mathrm{\,Ge\kern -0.1em V}}^2$. In each case, the first error is statistical and the second systematic.