Observation of J / ψ p Resonances Consistent with Pentaquark States in Λ b 0 → J / ψ K − p Decays
- R. Aaij
- B. Adeva
- M. Adinolfi
- A. A. Affolder
- Z. Ajaltouni
- S. Akar
- J. Albrecht
- F. Alessio
- Michael Thomas Alexander
- S. Ali
- G. Alkhazov
- P. Álvarez Cartelle
- Antonio Augusto Alves Junior
- S. Amato
- S. Amerio
- Y. Amhis
- L. An
- L. Anderlini
- J. Anderson
- G. Andreassi
- M. Andreotti
- J. E. Andrews
- R. B. Appleby
- O. Aquines Gutierrez
- F. Archilli
- P. d’Argent
- A. Artamonov
- M. Artuso
- E. Aslanides
- G. Auriemma
- M. Baalouch
- S. Bachmann
- J. J. Back
- A. Badalov
- C. Baesso
- W. Baldini
- Roger John Barlow
- C. Barschel
- S. Barsuk
- W. Barter
- V. Batozskaya
- V. Battista
- A. Bay
- L. Beaucourt
- J. Beddow
- F. Bedeschi
- I. Bediaga
- L. J. Bel
- V. Bellée
- N. Belloli
- I. Belyaev
- E. Ben-Haim
- G. Bencivenni
- S. Benson
- J. Benton
- Alexander Berezhnoy
- R. Bernet
- A. Bertolin
- M.-O. Bettler
- M. van Beuzekom
- A. Bień
- S. Bifani
- P. Billoir
- T. Bird
- A. Birnkraut
- A. Bizzeti
- T. Blake
- F. Blanc
- J. Blouw
- S. Blusk
- V. Bocci
- A. Bondar
- N. Bondar
- Walter Marcello Bonivento
- S. Borghi
- M. Borsato
- T. J. V. Bowcock
- E. Bowen
- C. Bozzi
- S. Braun
- M. Britsch
- T. Britton
- J. Brodzicka
- N. H. Brook
- A. Bursche
- J. Buytaert
- S. Cadeddu
- R. Calabrese
- M. Calvi
- M. Calvo Gomez
- P. Campana
- D. H. Cámpora Pérez
- L. Capriotti
- A. Carbone
- G. Carboni
- R. Cardinale
- A. Cardini
- P. Carniti
- L. Carson
- K. Carvalho Akiba
- MWM. Williams
Physical Review Letters · 2015 · American Physical Society
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Abstract
Observations of exotic structures in the J/ψp channel, which we refer to as charmonium-pentaquark states, in Λ_{b}^{0}→J/ψK^{-}p decays are presented. The data sample corresponds to an integrated luminosity of 3 fb^{-1} acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis of the three-body final state reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J/ψp mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380±8±29 MeV and a width of 205±18±86 MeV, while the second is narrower, with a mass of 4449.8±1.7±2.5 MeV and a width of 39±5±19 MeV. The preferred J^{P} assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.