A search for the rare decays B_s^0→μ^+μ^- and B^0→μ^+μ^- is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb^-1. An excess of B_s^0→μ^+μ^- decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B_s^0→μ^+μ^-)=(3.0±0.6_-0.2^+0.3)×10^-9, where the first uncertainty is statistical and the second systematic. The first measurement of the B_s^0→μ^+μ^- effective lifetime, τ(B_s^0→μ^+μ^-)=2.04±0.44±0.05 ps, is reported. No significant excess of B^0→μ^+μ^- decays is found, and a 95% confidence level upper limit, B(B^0→μ^+μ^-)<3.4×10^-10, is determined. All results are in agreement with the standard model expectations.
Measurement of the B_s^0→μ^+μ^- Branching Fraction and Effective Lifetime and Search for B^0→μ^+μ^- Decays
Veltri, M;
2017
Abstract
A search for the rare decays B_s^0→μ^+μ^- and B^0→μ^+μ^- is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb^-1. An excess of B_s^0→μ^+μ^- decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B_s^0→μ^+μ^-)=(3.0±0.6_-0.2^+0.3)×10^-9, where the first uncertainty is statistical and the second systematic. The first measurement of the B_s^0→μ^+μ^- effective lifetime, τ(B_s^0→μ^+μ^-)=2.04±0.44±0.05 ps, is reported. No significant excess of B^0→μ^+μ^- decays is found, and a 95% confidence level upper limit, B(B^0→μ^+μ^-)<3.4×10^-10, is determined. All results are in agreement with the standard model expectations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
