Observation of X(2370) and search for X(2120) in J/psi ->gamma KKeta' : BESIII Collaboration

• Using a sample of 1.31x109J/psi events collected with the BESIII detector, we perform a study of J/psi -> gamma KKeta '. X(2370) is observed in the KKeta ' invariant-mass distribution with a statistical significance of 8.3 sigma. Its resonance parameters are measured to be M=2341.6 +/- 6.5(stat.)+/- 5.7(syst.)MeV/c2 and Gamma =117 +/- 10(stat.)+/- 8(syst.)MeV. The product branching fractions for J/psi -> gamma X(2370),X(2370)-> K+K-eta ' and J/psi -> gamma X(2370),X(2370)-> KS0KS0 eta ' are determined to be (1.79 +/- 0.23(stat.)+/- 0.65(syst.))x10-5 and (1.18 +/- 0.32(stat.)+/- 0.39(syst.))x10-5, respectively. No evident signal for X(2120) is observed in the KKeta ' invariant-mass distribution. The upper limits for the product branching fractions of B(J/psi -> gamma X(2120)-> gamma K+K-eta ') and B(J/psi -> gamma X(2120)-> gamma KS0KS0 eta ') are determined to be 1.49x10-5 and 6.38x10-6 at the 90% confidence level, respectively.

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NATURVETENSKAP  -- Matematik -- Matematisk analys (hsv//swe)

NATURAL SCIENCES  -- Mathematics -- Mathematical Analysis (hsv//eng)

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