Observation of $\Lambda_{b}^{0} \to \Lambda_{c}^{+} \bar{D}^{()0} K^{-}$ and $\Lambda_{b}^{0} \to \Lambda_{c}^{+} D_{s}^{-}$ decays

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2024, Vol.84 (6)
• Main Authors: Aaij, Roel, Abdelmotteleb, Ahmed Sameh Wagih, Abellan Beteta, Carlos, Abudinén, Fernando Jesus, Ackernley, Thomas, Adeva, Bernardo, Adinolfi, Marco, Adlarson, Patrik Harri, Agapopoulou, Christina, Aidala, Christine Angela, Ajaltouni, Ziad, Akar, Simon, Akiba, Kazuyoshi, Albicocco, Pietro, Albrecht, Johannes, Alessio, Federico, Alexander, Michael, Alfonso Albero, Alejandro, Aliouche, Zakariya, Alvarez Cartelle, Paula, Amalric, Renaud, Amato, Sandra, Amey, Jake Lewis, Amhis, Yasmine, An, Liupan, Anderlini, Lucio, Andersson, Martin, Andreianov, Aleksei, Andreola, Pasquale, Andreotti, Mirco, Andreou, Dimitra, Anelli, Alessia, Ao, Dong, Archilli, Flavio, Argenton, Matteo, Arguedas Cuendis, Sergio, Artamonov, Alexander, Artuso, Marina, Aslanides, Elie, Atzeni, Michele, Audurier, Benjamin, Bacher, David, Bachiller Perea, Irene, Bachmann, Sebastian, Bachmayer, Marie, Back, John, Baladron Rodriguez, Pablo, Balagura, Vladislav, Baldini, Wander, Baptista de Souza Leite, Juan, Barbetti, Matteo, Barbosa, Ivanildo Rui, Barlow, Roger, Barsuk, Sergey, Barter, William, Bartolini, Matteo, Bartz, Justin, Baryshnikov, Fedor, Basels, Jan-Marc, Bassi, Giovanni, Batsukh, Baasansuren, Battig, Alexander, Bay, Aurelio, Beck, Anja, Becker, Maik, Bedeschi, Franco, Bediaga, Ignacio, Beiter, Andrew, Belin, Samuel, Bellee, Violaine, Belous, Konstantin, Belov, Ilia, Belyaev, Ivan, Benane, Gaya, Bencivenni, Giovanni, Ben-Haim, Eli, Berezhnoy, Alexander, Bernet, Roland, Bernet Andres, Sergi, Bernstein, Harris Conan, Bertella, Claudia, Bertolin, Alessandro, Betancourt, Christopher, Betti, Federico, Bex, Josh, Bezshyiko, Iaroslava, Bhom, Jihyun, Bieker, Martin Stefan, Biesuz, Nicolo Vladi, Billoir, Pierre, Biolchini, Alice, Birch, Matthew, Bishop, Fionn Caitlin Ros, Bitadze, Alexander, Bizzeti, Andrea, Blago, Michele Piero, Blake, Thomas, Blanc, Frederic, Blank, Jonah Evan, Blusk, Steven
• Format: Article
• Language: English
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-024-12752-3

The decays $\Lambda_b^0 \to \Lambda_c^+\bar{D}^{(*)0}K^-$ and $\Lambda_b^0 \to \Lambda_c^+ D_s^{*-}$ are observed for the first time, in proton-proton collision data at $\sqrt{s}=13$TeV corresponding to an integrated luminosity of 5.4 fb^{-1}$ collected with the LHCb detector. Their ratios of branching fractions with respect to the $\Lambda_b^0\!\to\Lambda_c^+\mathrm{D}_s^-$ mode are measured to be \begin{align*} \begin{split} \frac{\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+\bar{D}^0 K^-)}{\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+ D_s^-)} & = 0.1908 {}_{-0.0034}^{+0.0036} {}_{-0.0018}^{+0.0016} \pm 0.0038 \\ \frac{\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+\bar{D}^{*0} K^-)}{\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+ D_s^-)} & = 0.589 {}_{-0.017}^{+0.018} {}_{-0.018}^{+0.017} \pm 0.012 \\ \frac{\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+ D_s^{*-})}{\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+ D_s^-)} & = 1.668 \pm 0.022 {}_{-0.055}^{+0.061}\ , \end{split} \end{align*} where the first uncertainties are statistical, the second systematic, and the third, for the $\Lambda_b^0 \to \Lambda_c^+ \bar{D}^{(*)0} K^-$ decays, are due to the uncertainties on the branching fractions of the $D_s^- \to K^- K^+ \pi^-$ and $\bar{D}^0 \to K^+\pi^-$ decay modes. The measured branching fractions probe factorization assumptions in effective theories and provide the normalization for future pentaquark searches in $\Lambda_b^0 \to \Lambda_c^+ \bar{D}^{(*)0}K^-$ decay channels.