The color-singlet contribution to e^+ e^- ->J/psi + X at the endpoint

TL;DR

This paper sums large logarithmic corrections in the color-singlet contribution to J/psi production in e+e- collisions at the endpoint, revealing a suppression compared to fixed-order predictions, thus improving theoretical accuracy.

Contribution

It provides the first consistent summation of leading and next-to-leading logarithms for the color-singlet contribution at the endpoint in J/psi production.

Findings

Color-singlet cross section is suppressed near endpoint.

Summation of logarithms improves theoretical predictions.

Addresses discrepancies with experimental observations.

Abstract

Recent observations of the J/psi spectrum produced in e^+e^- collisions at the Upsilon(4S) resonance are in conflict with fixed-order calculations using Non-Relativsitic QCD effective theory (NRQCD). One problem is an enhancement in the cross section when the J/psi has maximal energy, due to large perturbative corrections (Sudakov logarithms). In a recent paper, the Sudakov logarithms in the color-octet contribution were summed by combining NRQCD with the Soft-Collinear Effective Theory. However to be consistent, the color-singlet contributions must also be summed in the endpoint region which was not done in that paper. In this paper, we sum the leading and next-to-leading logarithms in the color-singlet contribution to the J/psi production cross section. We find that the color-singlet cross section is suppressed near endpoint compared to the fixed order NRQCD prediction.