As part of the SFB 876, data from the LHCb experiment at CERN is analyzed by the project C5. A major challenge is to observe the variety of events and detect the most interesting ones while their occurrence is very rare. The LHCb-group has now succeeded in cooperation with a further experiment at CERN, the CMS experiment, to observe the yet rare decay of a B-meson. The decay B_s⁰ → μ⁺ μ^- was detected while the 50 observed decays yield a branching ratio of about 3 ∙ 10⁻⁹ from more than 10¹⁴ proton-proton collisions. The importance of this measure, which was published in the journal Nature, is very high, since it represents an extremely sensitive test of the standard model of particle physics. The measured value is in excellent agreement with the expectations of the standard model, so that new physics models are severely limited. Through the collaboration within the SFB 876 both the quality of the data analysis and thus the sensitivity of the measurements should be increased even further.

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14474.html