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

TL;DR

This paper calculates the cross sections for exclusive production of heavy quarkonium plus a photon in e+ e- annihilation at 10.58 GeV, providing predictions for experimental detection at B factories.

Contribution

It presents leading-order NRQCD calculations for heavy quarkonium plus photon production, including both S-wave and P-wave states, at a specific energy.

Findings

Predicted cross sections: 80 fb for eta_c, 50 fb for eta_c(2S)

Chi_{c1} has a large cross section of about 14 fb

Bottomonium states eta_b and chi_{bJ} have cross sections around 3 fb

Abstract

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 root-s=10.58 GeV. The NRQCD 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 = eta_c and eta_c(2S), respectively. Among P-wave spin-triplet charmonia, chi_{c1} has a particularly large cross section of about 14 fb. The cross sections for bottomonium states eta_b and chi_{bJ} 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.