$O(\alpha_s)$ corrections to $J/\psi+\chi_{cJ}$ production at $B$ factories

TL;DR

This paper calculates the next-to-leading order QCD corrections to the production of $J/ heta$ and $ heta_{cJ}$ states in electron-positron collisions at B factories, providing detailed analysis and confirming theoretical predictions about helicity suppression.

Contribution

It presents the first detailed NLO helicity amplitude calculations for $e^+e^- o J/ heta + heta_{cJ}$ within NRQCD, including asymptotic expressions and polarization analysis.

Findings

NLO corrections significantly affect cross section predictions.

Double logarithms are linked to helicity-suppressed channels.

Predictions align with experimental measurements at B factories.

Abstract

We investigate the ${\cal O}(\alpha_s)$ corrections to $e^+e^-\to J/\psi(\psi')+\chi_{cJ}$ ($J=0,1,2$) in the NRQCD factorization approach. These next-to-leading order (NLO) corrections are calculated at the level of helicity amplitude. We have made a detailed analysis for both polarized and unpolarized cross sections, and compared our predictions with the measurements at the $B$ factories. We also derive the asymptotic expressions for each of the NLO helicity amplitudes, and confirm the earlier speculation that at NLO in $\alpha_s$, the double logarithm of type $\ln^2 (s/m_c^2)$ appearing in the NRQCD short-distance coefficient is always associated with the helicity-suppressed channels.