# Measurement of the ratio of branching fractions B(B¯¯¯0→D∗+τ−ν¯τ))/B(B¯¯¯0→D∗+μ−ν¯μ)

Abstract : The branching fraction ratio R(D∗)≡B(B¯¯¯0→D∗+τ−ν¯τ)/B(B¯¯¯0→D∗+μ−ν¯μ) is measured using a sample of proton-proton collision data corresponding to 3.0\invfb of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ−→μ−ν¯μντ. The semitauonic decay is sensitive to contributions from non-Standard-Model particles that preferentially couple to the third generation of fermions, in particular Higgs-like charged scalars. A multidimensional fit to kinematic distributions of the candidate B¯¯¯0 decays gives R(D∗)=0.336±0.027(stat)±0.030(syst). This result, which is the first measurement of this quantity at a hadron collider, is 2.1 standard deviations larger than the value expected from lepton universality in the Standard Model.
Type de document :
Article dans une revue
Physical Review Letters, American Physical Society, 2015, 115, pp.111803. 〈10.1103/PhysRevLett.115.111803〉

http://hal.in2p3.fr/in2p3-01169706
Contributeur : Sabine Starita <>
Soumis le : mardi 30 juin 2015 - 09:51:34
Dernière modification le : jeudi 18 janvier 2018 - 01:51:25

### Citation

R. Aaij, Y. Amhis, S. Barsuk, M. Borsato, O. Kochebina, et al.. Measurement of the ratio of branching fractions B(B¯¯¯0→D∗+τ−ν¯τ))/B(B¯¯¯0→D∗+μ−ν¯μ). Physical Review Letters, American Physical Society, 2015, 115, pp.111803. 〈10.1103/PhysRevLett.115.111803〉. 〈in2p3-01169706〉

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