Analytical Forms for Cross Sections of Di-lepton Production from $e^+e^-$ Collisions around the $J/\psi$ Resonance

TL;DR

This paper derives precise analytical formulas for the cross sections of electron-positron collisions producing lepton pairs near the $J/\psi$ resonance, including resonance, interference, and higher-order effects, applicable also to the $\psi(3686)$ resonance.

Contribution

The paper provides new, highly accurate analytical expressions for cross sections near the $J/\psi$ resonance, incorporating higher-order corrections and interference effects.

Findings

Analytic formulas with 0.1% precision for $J/\psi$ resonance cross sections.

Inclusion of higher-order vacuum polarization and initial-state radiation corrections.

Formulas applicable to the $\psi(3686)$ resonance.

Abstract

A detailed theoretical derivation of the cross sections of $e^+e^- \to e^+e^-$ and $e^+e^- \to \mu^+\mu^-$ around the $J/\psi$ resonance is reported. The resonance and interference parts of the cross sections, related to $J/\psi$ resonance parameters, are calculated. Higher-order corrections for vacuum polarization and initial-state radiation are considered. An arbitrary upper limit of radiative correction integration is involved. Full and simplified versions of analytic formulae are given with precision at the level of 0.1% and 0.2%, respectively. Moreover, the results obtained in the paper can be applied to the case of the $\psi(3686)$ resonance.