Measurement of the Ratio of Branching Fractions B ( B ¯ 0 → D * + τ − ν ¯ τ ) / B ( B ¯ 0 → D * + μ − ν ¯ μ )
- R. Aaij
- B. Adeva
- M. Adinolfi
- A. A. Affolder
- Z. Ajaltouni
- S. Akar
- J. Albrecht
- F. Alessio
- Michael Thomas Alexander
- S. Ali
- G. Alkhazov
- P. Álvarez Cartelle
- Antonio Augusto Alves Junior
- S. Amato
- S. Amerio
- Y. Amhis
- L. An
- L. Anderlini
- J. Anderson
- G. Andreassi
- M. Andreotti
- J. E. Andrews
- R. B. Appleby
- O. Aquines Gutierrez
- F. Archilli
- P. d’Argent
- A. Artamonov
- M. Artuso
- E. Aslanides
- G. Auriemma
- M. Baalouch
- S. Bachmann
- John J Back
- A. Badalov
- C. Baesso
- W. Baldini
- Roger John Barlow
- C. Barschel
- S. Barsuk
- W. Barter
- V. Batozskaya
- V. Battista
- A. Bay
- L. Beaucourt
- J. Beddow
- F. Bedeschi
- I. Bediaga
- L. J. Bel
- V. Bellée
- I. Belyaev
- E. Ben-Haim
- G. Bencivenni
- S. Benson
- J. Benton
- Alexander Berezhnoy
- R. Bernet
- A. Bertolin
- M.-O. Bettler
- M. van Beuzekom
- A. Bień
- S. Bifani
- T. Bird
- A. Birnkraut
- A. Bizzeti
- T. Blake
- F. Blanc
- J. Blouw
- S. Blusk
- V. Bocci
- A. Bondar
- N. Bondar
- Walter Marcello Bonivento
- S. Borghi
- M. Borsato
- T. J. V. Bowcock
- E. Bowen
- C. Bozzi
- S. Braun
- D. Brett
- M. Britsch
- T. Britton
- J. Brodzicka
- N. H. Brook
- A. Bursche
- J. Buytaert
- S. Cadeddu
- R. Calabrese
- M. Calvi
- M. Calvo Gomez
- P. Campana
- D. H. Cámpora Pérez
- L. Capriotti
- A. Carbone
- G. Carboni
- R. Cardinale
- A. Cardini
- P. Carniti
- L. Carson
- K. Carvalho Akiba
- G. Casse
- MWM. Williams
Physical Review Letters · 2015 · American Physical Society
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Abstract
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.