Next-to-leading-order time-like rho electromagnetic form factors in ${k_{\rm T}}$ factorization

TL;DR

This paper computes the time-like rho electromagnetic form factor using $k_T$ factorization including NLO corrections, revealing twist-3 dominance and consistency with experimental data.

Contribution

It introduces a next-to-leading-order calculation of the rho meson EM form factor in the $k_T$ factorization framework, highlighting twist-3 dominance due to end-point effects.

Findings

NLO correction to LO form factor magnitude is below 30% at high $Q^2$.

Twist-3 contributions dominate over twist-2 in the rho meson EM form factor.

Predictions agree with BABAR measurements at $ oot s=10.58$ GeV.

Abstract

We calculate the time-like $\rho$ electromagnetic (EM) form factor in the $k_T$ factorization formalism by including the next-to-leading-order (NLO) corrections of the leading-twist and sub-leading twist contributions. It's observed that the NLO correction to the magnitude of the LO leading-twist form factor is lower than $30\%$ at large invariant mass squared $Q^2 > 30 \text{GeV}^2$. It is found that the $\rho$ meson EM form factor is dominated by twist-3 contribution instead of by twist-2 one because of the end-point enhancement. The theoretical predictions of the moduli of three helicity amplitudes and total cross section are analyzed at $\sqrt{s}=10.58$ GeV, which are consistent with measurements from BABAR Collaboration.