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arXiv · 2501.12779

Observation of the $Λ_b^0 \to J/ψΞ^- K^+$ and $Ξ_b^0 \to J/ψΞ^- π^+$ 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 observation of the $Ξ_b^0 \to J/ψΞ^- π^+$ decay and the most precise measurement of the branching fraction of the $Λ_b^0 \to J/ψΞ^- K^+$ decay are reported, using proton-proton collision data from the LHCb experiment collected in 2016--2018 at a centre-of-mass energy of 13~TeV, corresponding to an integrated luminosity of 5.4~fb$^{-1}$. Using the $Λ_b^0 \to J/ψΛ$ and $Ξ_b^0 \to J/ψΞ^-$ decays as normalisation channels, the ratios of branching fractions are measured to be: \[ \frac{\mathcal{B}(Λ_b^0 \to J/ψΞ^- K^+)}{\mathcal{B}(Λ_b^0 \to J/ψΛ)} = (1.17 \pm 0.14 \pm 0.08)\times 10^{-2} \, , \] \[ \frac{\mathcal{B}(Ξ_b^0 \to J/ψΞ^- π^+)}{\mathcal{B}(Ξ_b^0 \to J/ψΞ^-)} = (11.9 \pm 1.4 \pm 0.6)\times 10^{-2}\, , \] where the first uncertainty is statistical and the second systematic.

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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. 2025-09-08. Observation of the $Λ_b^0 \to J/ψΞ^- K^+$ and $Ξ_b^0 \to J/ψΞ^- π^+$ decays. https://doi.org/10.1140/epjc%2Fs10052-025-14129-6

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