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arXiv · 2402.05523

Observation of the $B_c^+ \to J/\psi \pi^+ \pi^0$ decay

LHCb collaboration·R. Aaij·A. S. W. Abdelmotteleb·C. Abellan Beteta·F. Abudinén·T. Ackernley·J. A. Adams·A. A. Adefisoye·B. Adeva·M. Adinolfi·P. Adlarson·C. Agapopoulou·C. A. Aidala·Z. Ajaltouni·S. Akar·K. Akiba·P. Albicocco·J. Albrecht·F. Alessio·M. Alexander·Z. Aliouche·P. Alvarez Cartelle·R. Amalric·S. Amato·J. L. Amey·Y. Amhis·L. An·L. Anderlini·M. Andersson·A. Andreianov·P. Andreola·M. Andreotti·D. Andreou·A. Anelli·D. Ao·F. Archilli·M. Argenton·S. Arguedas Cuendis·A. Artamonov·M. Artuso·E. Aslanides·M. Atzeni·B. Audurier·D. Bacher·I. Bachiller Perea·S. Bachmann·M. Bachmayer·J. J. Back·P. Baladron Rodriguez·V. Balagura·W. Baldini·J. Baptista de Souza Leite·M. Barbetti·I. R. Barbosa·R. J. Barlow·S. Barsuk·W. Barter·M. Bartolini·J. Bartz·F. Baryshnikov·J. M. Basels·G. Bassi·B. Batsukh·A. Battig·A. Bay·A. Beck·M. Becker·F. Bedeschi·I. B. Bediaga·A. Beiter·S. Belin·V. Bellee·K. Belous·I. Belov·I. Belyaev·G. Benane·G. Bencivenni·E. Ben-Haim·A. Berezhnoy·R. Bernet·S. Bernet Andres·C. Bertella·A. Bertolin·C. Betancourt·F. Betti·J. Bex·Ia. Bezshyiko·J. Bhom·M. S. Bieker·N. V. Biesuz·P. Billoir·A. Biolchini·M. Birch·F. C. R. Bishop·A. Bitadze·A. Bizzeti·T. Blake·F. Blanc·J. E. Blank·S. Blusk
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Abstract

The first observation of the $B_c^+ \to J/\psi \pi^+ \pi^0$ decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV. The ratio of its branching fraction relative to the $B_c^+ \to J/\psi \pi^+$ channel is measured to be $$ \frac{ {\cal{B}}( B_c^+ \to J/\psi \pi^+\pi^0 ) } { {\cal{B}}( B_c^+ \to J/\psi \pi^+ ) } = 2.80 \pm 0.15 \pm 0.11 \pm 0.16 \,, $$ where the first uncertainty is statistical, the second systematic and the third related to imprecise knowledge of the branching fractions for $B^+ \to J/\psi K^{*+}$ and $B^+ \to J/\psi K^+$ decays, which are used to determine the $\pi^0$ detection efficiency. The $\pi^+\pi^0$ mass spectrum is found to be consistent with the dominance of an intermediate $\rho^+$ contribution in accordance with a model based on QCD factorisation.

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LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, J. A. Adams, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis, L. An, L. Anderlini, M. Andersson, A. Andreianov, P. Andreola, M. Andreotti, D. Andreou, A. Anelli, D. Ao, F. Archilli, M. Argenton, S. Arguedas Cuendis, A. Artamonov, M. Artuso, E. Aslanides, M. Atzeni, B. Audurier, D. Bacher, I. Bachiller Perea, S. Bachmann, M. Bachmayer, J. J. Back, P. Baladron Rodriguez, V. Balagura, W. Baldini, J. Baptista de Souza Leite, M. Barbetti, I. R. Barbosa, R. J. Barlow, S. Barsuk, W. Barter, M. Bartolini, J. Bartz, F. Baryshnikov, J. M. Basels, G. Bassi, B. Batsukh, A. Battig, A. Bay, A. Beck, M. Becker, F. Bedeschi, I. B. Bediaga, A. Beiter, S. Belin, V. Bellee, K. Belous, I. Belov, I. Belyaev, G. Benane, G. Bencivenni, E. Ben-Haim, A. Berezhnoy, R. Bernet, S. Bernet Andres, C. Bertella, A. Bertolin, C. Betancourt, F. Betti, J. Bex, Ia. Bezshyiko, J. Bhom, M. S. Bieker, N. V. Biesuz, P. Billoir, A. Biolchini, M. Birch, F. C. R. Bishop, A. Bitadze, A. Bizzeti, T. Blake, F. Blanc, J. E. Blank, S. Blusk. 2024-02-08. Observation of the $B_c^+ \to J/\psi \pi^+ \pi^0$ decay. https://doi.org/10.1007/jhep04(2024)151

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