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 3.0fb-1 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.

Measurement of the ratio of branching fractions B((B)over-bar(0) -> D-*(+)tau(-)(nu)over-bar(tau))/B((B)over-bar(0) -> D-*(+)mu(-)(nu)over-bar(mu))

COGONI, VIOLETTA;Dettori, F.;Lai, A.;MANCA, GIULIA;OLDEMAN, RUDOLF GERHARD CHRISTIAAN;SAITTA, BIAGIO;VACCA, CLAUDIA;
2015

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 3.0fb-1 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.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/192516
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