Observation of the Doubly Charmed Baryon Ξcc + +

R. Aaij, B. Adeva, Z. Ajaltouni, S. Akar, F. Alessio, M. Alexander, A. Alfonso Albero, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, S. Amerio, Y. Amhis, L. An, L. Anderlini, G. Andreassi, M. Andreotti, J. E. Andrews, R. B. ApplebyF. Archilli, P. D'Argent, J. Arnau Romeu, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, M. Baalouch, I. Babuschkin, S. Bachmann, J. J. Back, A. Badalov, C. Baesso, S. Baker, V. Balagura, K. Carvalho Akiba, M. Ferro-Luzzi, T. Ketel, J. Van Leerdam, M. Merk, C. J.G. Onderwater, G. Raven, M. Schiller, N. Serra, B. Storaci, V. Syropoulos, J. Van Tilburg, S. Tolk, P. Tsopelas, N. Tuning, (LHCb Collaboration)

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A highly significant structure is observed in the Λc+K-π+π+ mass spectrum, where the Λc+ baryon is reconstructed in the decay mode pK-π+. The structure is consistent with originating from a weakly decaying particle, identified as the doubly charmed baryon Ξcc++. The difference between the masses of the Ξcc++ and Λc+ states is measured to be 1334.94±0.72(stat.)±0.27(syst.) MeV/c2, and the Ξcc++ mass is then determined to be 3621.40±0.72(stat.)±0.27(syst.)±0.14(Λc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Λc+ mass. The state is observed in a sample of proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb-1, and confirmed in an additional sample of data collected at 8 TeV.

Original languageEnglish
Article number112001
JournalPhysical Review Letters
Issue number11
Publication statusPublished - 11 Sept 2017


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