Observation and spin-parity determination of the X(1835) in J/? ? ?K0SK0S?
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We report an observation of the process J/? ? ?X(1835) ? ?K0SK0S? at low K0SK0S mass with a statistical significance larger than 12.9? using a data sample of 1.31 × 109 J/? events collected with the BESIII detector. In this region of phase space the K0SK0S system is dominantly produced through the f0(980). By performing a partial wave analysis, we determine the spin parity of the X(1835) to be JPC = 0?+. The mass and width of the observed X(1835) are 1844 ± 9(stat)+16?25 (syst) MeV/c2 and 192+20?17 (stat)+62?43 (syst) MeV, respectively, which are consistent with the results obtained by BESIII in the channel J/? ? ??+???'. © 2015 American Physical Society.