Evidence of gamma(1S) -˃ J/Psi +chi(c1) and search for double-charmonium production in gamma(1S) and gamma(2S) decays

Abstract

Using data samples of 102 x 10(6) gamma(1S) and 158 x 10(6) gamma(2S) events collected with the Belle detector, a first experimental search has been made for double-charmonium production in the exclusive decays gamma(1S, 2S) --˃ J/psi(psi'# + X, where X = eta#c##chi#cJ# #J = 0, 1, 2#, eta#c##2S#, X#3940#, and X#4160#. No significant signal is observed in the spectra of the mass recoiling against the reconstructed J/psi or psi' except for the evidence of chi#c1# production with a significance of 4.6 sigma for gamma#1S# -˃ J/psi + chi#c1#. The measured branching fraction B#gamma#1S# -˃ J/psi + chi#c1## is [3.90 +/- 1.21 #stat# +/- 0.23#syst# x 10#-6#. The 90% C.L. upper limits on the branching fractions of the other modes having a significance of less than 3 sigma are determined. These results are consistent with theoretical calculations using the nonrelativistic QCD factorization approach.