Measurement of the Ratio of Branching Fractions B ( B ¯ 0 → D + τ − ν ¯ τ ) / B ( B ¯ 0 → D + μ − ν ¯ μ )

The branching fraction ratio R(D^{*})≡B(B[over ¯]^{0}→D^{*+}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]^{0}→D^{*+}μ^{-}ν[over ¯]_{μ}) 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 le...

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Published in:Physical review letters Vol. 115; no. 11; p. 111803
Main Authors: Aaij, R., Adeva, B., Adinolfi, M., Affolder, A., Ajaltouni, Z., Akar, S., Albrecht, J., Alessio, F., Alexander, M., Ali, S., Alkhazov, G., Alvarez Cartelle, P., Alves, A. A., Amato, S., Amerio, S., Amhis, Y., An, L., Anderlini, L., Anderson, J., Andreassi, G., Andreotti, M., Andrews, J. E., Appleby, R. B., Aquines Gutierrez, O., Archilli, F., d’Argent, P., Artamonov, A., Artuso, M., Aslanides, E., Auriemma, G., Baalouch, M., Bachmann, S., Back, J. J., Badalov, A., Baesso, C., Baldini, W., Barlow, R. J., Barschel, C., Barsuk, S., Barter, W., Batozskaya, V., Battista, V., Bay, A., Beaucourt, L., Beddow, J., Bedeschi, F., Bediaga, I., Bel, L. J., Bellee, V., Belyaev, I., Ben-Haim, E., Bencivenni, G., Benson, S., Benton, J., Berezhnoy, A., Bernet, R., Bertolin, A., Bettler, M.-O., van Beuzekom, M., Bien, A., Bifani, S., Bird, T., Birnkraut, A., Bizzeti, A., Blake, T., Blanc, F., Blouw, J., Blusk, S., Bocci, V., Bondar, A., Bondar, N., Bonivento, W., Borghi, S., Borsato, M., Bowcock, T. J. V., Bowen, E., Bozzi, C., Braun, S., Brett, D., Britsch, M., Britton, T., Brodzicka, J., Brook, N. H., Bursche, A., Buytaert, J., Cadeddu, S., Calabrese, R., Calvi, M., Calvo Gomez, M., Campana, P., Campora Perez, D., Capriotti, L., Carbone, A., Carboni, G., Cardinale, R., Cardini, A., Carniti, P., Carson, L., Carvalho Akiba, K., Casse, G.
Format: Journal Article
Language:English
Published: United States American Physical Society 11.09.2015
Subjects:
Experiments
Física de partícules
Particle physics
ISSN:0031-9007, 1079-7114
Online Access:Get full text
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Summary:The branching fraction ratio R(D^{*})≡B(B[over ¯]^{0}→D^{*+}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]^{0}→D^{*+}μ^{-}ν[over ¯]_{μ}) 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^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ}. 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[over ¯]^{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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ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.115.111803