Relativistic corrections to exclusive $chi_cJ _s16 gamma$ production from $e^_s16 e^-$ annihilation

Abstract

We calculate in the nonrelativistic QCD (NRQCD) factorization framework all leading relativistic corrections to the exclusive production of χcJ_s16Î_s11 in e_s16e- annihilation. In particular, we compute for the first time contributions induced by octet operators with a chromoelectric field. The matching coefficients multiplying production long distance matrix elements (LDMEs) are determined through perturbative matching between QCD and NRQCD at the amplitude level. Technical challenges encountered in the nonrelativistic expansion of the QCD amplitudes are discussed in detail. The main source of uncertainty comes from the not so well known LDMEs. Accounting for it, we provide the following estimates for the production cross sections at s=10.6â_s08‰â_s08‰GeV: σ(e_s16e-→χc0_s16Î_s11)=(1.4±0.3)â_s08‰â_s08‰fb, σ(e_s16e-→χc1_s16Î_s11)=(15.0±3.3)â_s08‰â_s08‰fb, and σ(e_s16e-→χc2_s16Î_s11)=(4.5±1.4)â_s08‰â_s08‰fb.