Eur. Phys. J. C (2024) 84: 237
https://doi.org/10.1140/epjc/s10052-024-12443-z

Regular Article - Experimental Physics

Observation of ${\Xi }_b^0\to {\Xi }_c^{+}{D}_s^{-}$ and ${\Xi }_b^{-}\to {\Xi }_c^0{D}_s^{-}$ decays

¹ Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, Brazil
² Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
³ Center for High Energy Physics, Tsinghua University, Beijing, China
⁴ Institute Of High Energy Physics (IHEP), Beijing, China
⁵ School of Physics State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
⁶ University of Chinese Academy of Sciences, Beijing, China
⁷ Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China
⁸ Consejo Nacional de Rectores (CONARE), San Jose, Costa Rica
⁹ Université Savoie Mont Blanc, CNRS, IN2P3-LAPP, Annecy, France
¹⁰ Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
¹¹ Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
¹² Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
¹³ Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France
¹⁴ LPNHE, Sorbonne Université, Paris Diderot Sorbonne Paris Cité, CNRS/IN2P3, Paris, France
¹⁵ I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany
¹⁶ Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
¹⁷ Max-Planck-Institut für Kernphysik (MPIK), Heidelberg, Germany
¹⁸ Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
¹⁹ School of Physics, University College Dublin, Dublin, Ireland
²⁰ INFN Sezione di Bari, Bari, Italy
²¹ INFN Sezione di Bologna, Bologna, Italy
²² INFN Sezione di Ferrara, Ferrara, Italy
²³ INFN Sezione di Firenze, Firenze, Italy
²⁴ INFN Laboratori Nazionali di Frascati, Frascati, Italy
²⁵ INFN Sezione di Genova, Genova, Italy
²⁶ INFN Sezione di Milano, Milano, Italy
²⁷ INFN Sezione di Milano-Bicocca, Milano, Italy
²⁸ INFN Sezione di Cagliari, Monserrato, Italy
²⁹ Università degli Studi di Padova, Università e INFN, Padova, Padova, Italy
³⁰ INFN Sezione di Pisa, Pisa, Italy
³¹ INFN Sezione di Roma La Sapienza, Roma, Italy
³² INFN Sezione di Roma Tor Vergata, Roma, Italy
³³ Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands
³⁴ Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, The Netherlands
³⁵ AGH - University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland
³⁶ Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland
³⁷ National Center for Nuclear Research (NCBJ), Warsaw, Poland
³⁸ Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania
³⁹ Affiliated with an institute covered by a cooperation agreement with CERN, Geneva, Switzerland
⁴⁰ DS4DS, La Salle, Universitat Ramon Llull, Barcelona, Spain
⁴¹ ICCUB, Universitat de Barcelona, Barcelona, Spain
⁴² Instituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
⁴³ Instituto de Fisica Corpuscular, Centro Mixto Universidad de Valencia - CSIC, Valencia, Spain
⁴⁴ European Organization for Nuclear Research (CERN), Geneva, Switzerland
⁴⁵ Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
⁴⁶ Physik-Institut, Universität Zürich, Zürich, Switzerland
⁴⁷ NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine
⁴⁸ Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine
⁴⁹ University of Birmingham, Birmingham, UK
⁵⁰ H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK
⁵¹ Cavendish Laboratory, University of Cambridge, Cambridge, UK
⁵² Department of Physics, University of Warwick, Coventry, UK
⁵³ STFC Rutherford Appleton Laboratory, Didcot, UK
⁵⁴ School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
⁵⁵ School of Physics and Astronomy, University of Glasgow, Glasgow, UK
⁵⁶ Oliver Lodge Laboratory, University of Liverpool, Liverpool, UK
⁵⁷ Imperial College London, London, UK
⁵⁸ Department of Physics and Astronomy, University of Manchester, Manchester, UK
⁵⁹ Department of Physics, University of Oxford, Oxford, UK
⁶⁰ Massachusetts Institute of Technology, Cambridge, MA, USA
⁶¹ University of Cincinnati, Cincinnati, OH, USA
⁶² University of Maryland, College Park, MD, USA
⁶³ Los Alamos National Laboratory (LANL), Los Alamos, NM, USA
⁶⁴ Syracuse University, Syracuse, NY, USA
⁶⁵ School of Physics and Astronomy, Monash University, Melbourne, Australia
⁶⁶ Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil
⁶⁷ School of Physics and Electronics, Hunan University, Changsha City, China
⁶⁸ Guangdong Provincial Key Laboratory of Nuclear Science, Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Institute of Quantum Matter, South China Normal University, Guangzhou, China
⁶⁹ Lanzhou University, Lanzhou, China
⁷⁰ School of Physics and Technology, Wuhan University, Wuhan, China
⁷¹ Departamento de Fisica, Universidad Nacional de Colombia, Bogota, Colombia
⁷² Universität Bonn - Helmholtz-Institut für Strahlen und Kernphysik, Bonn, Germany
⁷³ Eotvos Lorand University, Budapest, Hungary
⁷⁴ INFN Sezione di Perugia, Perugia, Italy
⁷⁵ Van Swinderen Institute, University of Groningen, Groningen, The Netherlands
⁷⁶ Universiteit Maastricht, Maastricht, The Netherlands
⁷⁷ Tadeusz Kosciuszko Cracow University of Technology, Cracow, Poland
⁷⁸ Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
⁷⁹ University of Michigan, Ann Arbor, Ann Arbor, MI, USA
⁸⁰ Departement de Physique Nucleaire (SPhN), Gif-Sur-Yvette, France
⁸¹ Universidade de Brasília, Brasília, Brazil
⁸² Centro Federal de Educacão Tecnológica Celso Suckow da Fonseca, Rio De Janeiro, Brazil
⁸³ Universidade Federal do Triângulo Mineiro (UFTM), Uberaba-MG, Brazil
⁸⁴ Central South U, Changsha, China
⁸⁵ Hangzhou Institute for Advanced Study, UCAS, Hangzhou, China
⁸⁶ LIP6, Sorbonne Universite, Paris, France
⁸⁷ Excellence Cluster ORIGINS, Munich, Germany
⁸⁸ Universidad Nacional Autónoma de Honduras, Tegucigalpa, Honduras
⁸⁹ Università di Bari, Bari, Italy
⁹⁰ Università di Bologna, Bologna, Italy
⁹¹ Università di Cagliari, Cagliari, Italy
⁹² Università di Ferrara, Ferrara, Italy
⁹³ Università di Firenze, Firenze, Italy
⁹⁴ Università di Genova, Genova, Italy
⁹⁵ Università degli Studi di Milano, Milano, Italy
⁹⁶ Università di Milano Bicocca, Milano, Italy
⁹⁷ Università di Padova, Padova, Italy
⁹⁸ Università di Perugia, Perugia, Italy
⁹⁹ Scuola Normale Superiore, Pisa, Italy
¹⁰⁰ Università di Pisa, Pisa, Italy
¹⁰¹ Università della Basilicata, Potenza, Italy
¹⁰² Università di Roma Tor Vergata, Roma, Italy
¹⁰³ Università di Siena, Siena, Italy
¹⁰⁴ Università di Urbino, Urbino, Italy
¹⁰⁵ Universidad de Alcalá, Alcalá de Henares, Spain
¹⁰⁶ Universidade da Coruña, Coruña, Spain
¹⁰⁷ CERN, 1211, Geneva 23, Switzerland

^a yshang@cern.ch

Received: 23 October 2023
Accepted: 12 January 2024
Published online: 7 March 2024

Abstract

The ${\mathrm{\Xi }}_b^0\to {\mathrm{\Xi }}_c^{+}{D}_s^{-}$ and ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Xi }}_c^0{D}_s^{-}$ decays are observed for the first time using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of $\sqrt{s}=13\text{TeV}$, corresponding to an integrated luminosity of $5.1{\text{fb}}^{-1}$. The branching fractions times the production cross-sections of ${\mathrm{\Xi }}_b$ baryons relative to that of ${\mathrm{\Lambda }}_b^0$ baryon are measured to be $$\begin{array}{cc}\hfill \mathcal{R}\left(\frac{{\mathrm{\Xi }}_b^0}{{\mathrm{\Lambda }}_b^0}\right)& \equiv \frac{\sigma \left({\mathrm{\Xi }}_b^0\right)}{\sigma \left({\mathrm{\Lambda }}_b^0\right)}\times \frac{\mathcal{B}({\mathrm{\Xi }}_b^0\to {\mathrm{\Xi }}_c^{+}{D}_s^{-})}{\mathcal{B}({\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^0{D}_s^{-})}\hfill \\ \hfill & =(15.8\pm 1.1\pm 0.6\pm 7.7)\%,\hfill \\ \hfill \mathcal{R}\left(\frac{{\mathrm{\Xi }}_b^{-}}{{\mathrm{\Lambda }}_b^0}\right)& \equiv \frac{\sigma \left({\mathrm{\Xi }}_b^{-}\right)}{\sigma \left({\mathrm{\Lambda }}_b^0\right)}\times \frac{\mathcal{B}({\mathrm{\Xi }}_b^{-}\to {\mathrm{\Xi }}_c^0{D}_s^{-})}{\mathcal{B}({\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^0{D}_s^{-})}\hfill \\ \hfill & =(16.9\pm 1.3\pm 0.9\pm 4.3)\%,\hfill \end{array}$$where the first uncertainties are statistical, the second systematic, and the third due to the uncertainties on the decay branching fractions of relevant charmed baryons. The masses of ${\mathrm{\Xi }}_b^0$ and ${\mathrm{\Xi }}_b^{-}$ baryons are measured to be $m_{{\mathrm{\Xi }}_b^0}=5791.12\pm 0.60\pm 0.45\pm 0.24\text{MeV}/c^2$ and $m_{{\mathrm{\Xi }}_b^{-}}=5797.02\pm 0.63\pm 0.49\pm 0.29\text{MeV}/c^2$, where the uncertainties are statistical, systematic, and those due to charmed-hadron masses, respectively.