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arXiv · 2412.11645

Test of lepton flavour universality with $B^+ \to K^+\pi^+\pi^-\ell^+\ell^-$ decays

LHCb collaboration·R. Aaij·A. S. W. Abdelmotteleb·C. Abellan Beteta·F. Abudinén·T. Ackernley·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·R. Ataíde Da Silva·M. Atzeni·B. Audurier·D. Bacher·I. Bachiller Perea·S. Bachmann·M. Bachmayer·J. J. Back·P. Baladron Rodriguez·V. Balagura·A. Balboni·W. Baldini·L. Balzani·H. Bao·J. Baptista de Souza Leite·C. Barbero Pretel·M. Barbetti·I. R. Barbosa·R. J. Barlow·M. Barnyakov·S. Barsuk·W. Barter·J. Bartz·J. M. Basels·S. Bashir·G. Bassi·B. Batsukh·P. B. Battista·A. Bay·A. Beck·M. Becker·F. Bedeschi·I. B. Bediaga·N. A. Behling·S. Belin·K. Belous·I. Belov·I. Belyaev·G. Benane·G. Bencivenni·E. Ben-Haim·A. Berezhnoy·R. Bernet·S. Bernet Andres·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
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Abstract

The first test of lepton flavor universality between muons and electrons using $B^+ \to K^+\pi^+\pi^-\ell^+\ell^-$ ($\ell=e,\mu$) decays is presented. The measurement is performed with data from proton-proton collisions collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of $9\mathrm{fb}^{-1}$. The ratio of branching fractions between $B^+ \to K^+\pi^+\pi^-e^+e^-$ and $B^+ \to K^+\pi^+\pi^-\mu^+\mu^-$decays is measured in the dilepton invariant-mass-squared range $1.1 < q^2 < 7.0~\mathrm{GeV}^2/c^4$ and is found to be $R_{K\pi\pi}^{-1} = 1.31^{+0.18}_{-0.17} \;(\mathrm{stat})\;^{+0.12}_{-0.09} \;(\mathrm{syst})$, in agreement with the standard model prediction. The first observation of the $B^+ \to K^+\pi^+\pi^-e^+e^-$ decay is also reported.

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LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, 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, R. Ataíde Da Silva, M. Atzeni, B. Audurier, D. Bacher, I. Bachiller Perea, S. Bachmann, M. Bachmayer, J. J. Back, P. Baladron Rodriguez, V. Balagura, A. Balboni, W. Baldini, L. Balzani, H. Bao, J. Baptista de Souza Leite, C. Barbero Pretel, M. Barbetti, I. R. Barbosa, R. J. Barlow, M. Barnyakov, S. Barsuk, W. Barter, J. Bartz, J. M. Basels, S. Bashir, G. Bassi, B. Batsukh, P. B. Battista, A. Bay, A. Beck, M. Becker, F. Bedeschi, I. B. Bediaga, N. A. Behling, S. Belin, K. Belous, I. Belov, I. Belyaev, G. Benane, G. Bencivenni, E. Ben-Haim, A. Berezhnoy, R. Bernet, S. Bernet Andres, 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. 2024-12-16. Test of lepton flavour universality with $B^+ \to K^+\pi^+\pi^-\ell^+\ell^-$ decays. https://doi.org/10.1103/physrevlett.134.181803

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