Test of lepton flavor universality using <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mn>0</mml:mn></mml:msup><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mrow><mml:mi>D</mml:mi></mml:mrow><mml:mrow><mml:mo>*</mml:mo><mml:mo>−</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi>τ</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mml:mrow><mml:mi>τ</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math> decays with hadronic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>τ</mml:mi></mml:math> channels
R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, H. Afsharnia, C. Agapopoulou, C. Aidala, Z. Ajaltouni, S. Akar, K. Carvalho Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Zakariya Aliouche, P. Álvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis, L. An, L. Anderlini, M. Andersson, A. Andreianov, M. Andreotti, D. Andreou, D. Ao, F. Archilli, A. Artamonov, M. Artuso, E. Aslanides, M. Atzeni, B. Audurier, I. Bachiller, S. Bachmann, Marie Bachmayer, J. J. Back, A. Bailly-reyre, P. Baladrón Rodríguez, V. Balagura, W. Baldini, J. Baptista de Souza Leite, M. Barbetti, R. J. Barlow, S. Barsuk, W. Barter, M. Bartolini, F. Baryshnikov, J. M. Basels, G. Bassi, B. Batsukh, A. Battig, A. Bay, A. Beck, M. Becker, F. Bedeschi, I. Bediaga, A. Beiter, S. Belin, V. Bellée, K. Belous, I. Belov, I. Belyaev, G. Benane, G. Bencivenni, E. Ben-Haim, A. Berezhnoy, R. Bernet, S. Bernet Andres, D. Berninghoff, H. C. Bernstein, C. Bertella, A. Bertolin, C. Betancourt, F. Betti, Ia. Bezshyiko, J. Bhom, L. Bian, M. S. Bieker, N. V. Biesuz, P. Billoir, A. Biolchini, M. Birch, F. C. R. Bishop, A. Bitadze, A. Bizzeti, Michele Piero Blago, T. Blake, F. Blanc, J. E. Blank, S. Blusk, D. Bobulska, Vladimir Bocharnikov, J. A. Boelhauve, O. Boente García
Abstract
The branching fraction $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\tau}}^{+}{\ensuremath{\nu}}_{\ensuremath{\tau}})$ is measured relative to that of the normalization mode ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ using hadronic ${\ensuremath{\tau}}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}({\ensuremath{\pi}}^{0}){\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ decays in proton-proton collision data at a center-of-mass energy of 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of $2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. The measured ratio is $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\tau}}^{+}{\ensuremath{\nu}}_{\ensuremath{\tau}})/\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+})=1.70\ifmmode\pm\else\textpm\fi{}0.1{0}_{\ensuremath{-}0.10}^{+0.11}$, where the first uncertainty is statistical and the second is related to systematic effects. Using established branching fractions for the ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ and ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\nu}}_{\ensuremath{\mu}}$ modes, the lepton universality test $\mathcal{R}({D}^{*\ensuremath{-}})\ensuremath{\equiv}\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\tau}}^{+}{\ensuremath{\nu}}_{\ensuremath{\tau}})/\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\nu}}_{\ensuremath{\mu}})$ is calculated, $\mathcal{R}({D}^{*\ensuremath{-}})=0.247\ifmmode\pm\else\textpm\fi{}0.015\ifmmode\pm\else\textpm\fi{}0.015\ifmmode\pm\else\textpm\fi{}0.012$, where the third uncertainty is due to the uncertainties on the external branching fractions. This result is consistent with the Standard Model prediction and with previous measurements.