Next-to-next-to-leading-order QCD corrections to $e^+e^-\to J/\psi+\eta_c$ at $B$ factories

TL;DR

This paper calculates the second-order QCD corrections to the process $e^+e^- o J/+_c$ at B factories, confirming NRQCD factorization at NNLO and improving theoretical predictions to match experimental data.

Contribution

First computation of NNLO QCD corrections for $e^+e^- o J/+_c$ within NRQCD, demonstrating factorization validity and enhanced prediction accuracy.

Findings

NNLO corrections reduce scale dependence

Perturbative convergence is reasonable

Prediction aligns with BaBar measurements

Abstract

Within the nonrelativistic QCD (NRQCD) factorization framework, we compute the long-awaited ${\mathcal O}(\alpha_s^2)$ correction for the exclusive double charmonium production process at $B$ factories, {\it i.e.}, $e^+e^-\to J/\psi+\eta_c$ at $\sqrt{s}=10.58$ GeV. For the first time, we confirm that NRQCD factorization does hold at next-to-next-to-leading-order (NNLO) for exclusive double charmonium production. It is found that including the NNLO QCD correction considerably reduces the renormalization scale dependence, and also implies the reasonable perturbative convergence behavior for this process. Our state-of-the-art prediction is consistent with the BaBar measurement within errors.