First evidence for the decay B(s)(0)→μ+ μ-.

Journal article

A search for the rare decays B(s)(0)→μ+ μ- and B(0)→μ+ μ- is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1  fb(-1) of proton-proton collisions at sqrt[s]=8  TeV and 1.0  fb(-1) at sqrt[s]=7  TeV. We observe an excess of B(s)(0)→μ+ μ- candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3×10(-4) corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of B(B(s)(0)→μ+ μ-)=(3.2(-1.2)(+1.5))×10(-9), where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the standard model expectation. The observed number of B(0)→μ+ μ- candidates is consistent with the background expectation, giving an upper limit of B(B(0)→μ+ μ-)<9.4×10(-10) at 95% confidence level.

Authors: Aaij, R; Abellan Beteta, C; Adametz, A; Adeva, B; Adinolfi, M

• Publication status: Published
• Journal: Physical Review Letters
• Volume: 110
• Issue: 2
• Pages: 021801
• Publication date: 2013-01-07
• DOI: 10.1103/physrevlett.110.021801
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English
• Keywords: LHCb Collaboration