Abstract
Observations of exotic structures in the channel, which we refer to as charmonium-pentaquark states, in decays are presented. The data sample corresponds to an integrated luminosity of acquired with the LHCb detector from 7 and 8 TeV 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 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 and a width of , while the second is narrower, with a mass of and a width of . The preferred assignments are of opposite parity, with one state having spin and the other .
2 More- Received 13 July 2015
DOI:https://doi.org/10.1103/PhysRevLett.115.072001
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© 2015 CERN, for the LHCb Collaboration
Viewpoint
Elusive Pentaquark Comes into View
Published 12 August 2015
A new type of particle containing five quarks has been observed by the LHCb experiment.
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