Measurement of the Ratio of Branching Fractions B (B¯ 0→ D*+ τたう-νにゅー¯ τたう)/B (B¯ 0→ D*+ μみゅー-νにゅー¯ μみゅー)

R Aaij, B Adeva, M Adinolfi, A Affolder, Z Ajaltouni… - Physical review …, 2015 - APS
R Aaij, B Adeva, M Adinolfi, A Affolder, Z Ajaltouni, S Akar, J Albrecht, F Alessio
Physical review letters, 2015APS
The branching fraction ratio R (D*)≡ B (B¯ 0→ D*+ τたう-νにゅー¯ τたう)/B (B¯ 0→ D*+ μみゅー-νにゅー¯ μみゅー) is
measured using a sample of proton-proton collision data corresponding to 3.0 fb-1 of
integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau
lepton is identified in the decay mode τたう-→ μみゅー-νにゅー¯ μみゅー νにゅー τたう. 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 …
The branching fraction ratio R(D*)≡B(B¯0→D*+τたう-νにゅー¯τたう)/B(B¯0→D*+μみゅー-νにゅー¯μみゅー) is measured using a sample of proton-proton collision data corresponding to of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode . 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 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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