Search for $C=+$ charmonium and bottomonium states in $e^+e^-\to \gamma+ X$ at B factories

Abstract

We study the production of $C=+$ charmonium states $X$ in $e^+e^-\to \gamma + X$ at B factories with $X=\eta_c(nS)$ (n=1,2,3), $\chi_{cJ}(mP)$ (m=1,2), and $^1D_2(1D)$. In the S and P wave case, contributions of tree-QED with one-loop QCD corrections are calculated within the framework of nonrelativistic QCD(NRQCD) and in the D-wave case only the tree-QED contribution are considered. We find that in most cases the QCD corrections are negative and moderate, in contrast to the case of double charmonium production $e^+e^-\to J/\psi + X$, where QCD corrections are positive and large in most cases. We also find that the production cross sections of some of these states in $e^+e^-\to \gamma + X$ are larger than that in $e^+e^-\to J/\psi + X$ by an order of magnitude even after the negative QCD corrections are included. So we argue that search for the X(3872), X(3940), Y(3940), and X(4160) in $e^+e^-\to \gamma + X$ at B factories may be helpful to clarify the nature of these states. For completeness, the production of bottomonium states in $e^+e^-$ annihilation is also discussed.