Exclusive heavy quarkonium +γ production from e+e- annihilation into a virtual photon

We compute the cross section for exclusive production of a photon associated with a heavy quarkonium H of charge-conjugation parity C=+1 from e+e- annihilation into a virtual photon at the center-of-momentum energy s=10.58GeV. The nonrelativistic QCD factorization formulas for the differential and total cross sections are obtained at leading order in the strong coupling and in the relative velocity of the heavy quark in the quarkonium rest frame. The predicted cross sections for the S-wave spin-singlet cases are about 80 fb and 50 fb for H=ηc and ηc(2S), respectively. Among P-wave spin-triplet charmonia, χc1 has a particularly large cross section of about 14 fb. The cross sections for bottomonium states ηb and χbJ are about 3 fb. A rough estimate of the background reveals that the signal significances for charmonium processes are sufficiently large enough to be detected with ease with the integrated luminosities available at the present B factories.