### Abstract

A test of lepton universality, performed by measuring the ratio of the branching fractions of the B^{0} → K^{*0}μ^{+}μ^{−} and B^{0} → K^{*0}e^{+}e^{−} decays, RK*0, is presented. The K^{*0} meson is reconstructed in the final state K^{+}π^{−}, which is required to have an invariant mass within 100 MeV/c^{2} of the known K^{*}(892)^{0} mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb^{−1}, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q^{2}, to be (Formula presented.) The corresponding 95.4% confidence level intervals are [0.52, 0.89] and [0.53, 0.94]. The results, which represent the most precise measurements of RK*0 to date, are compatible with the Standard Model expectations at the level of 2.1–2.3 and 2.4–2.5 standard deviations in the two q^{2} regions, respectively.[Figure not available: see fulltext.].

Original language | English (US) |
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Article number | 55 |

Journal | Journal of High Energy Physics |

Volume | 2017 |

Issue number | 8 |

DOIs | |

State | Published - Aug 1 2017 |

### Keywords

- B physics
- Branching fraction
- Hadron-Hadron scattering (experiments)
- Rare decay

### ASJC Scopus subject areas

- Nuclear and High Energy Physics

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## Cite this

^{0}→ K

^{*0}ℓ

^{+}ℓ

^{−}decays.

*Journal of High Energy Physics*,

*2017*(8), [55]. https://doi.org/10.1007/JHEP08(2017)055