Rosenbluth separation of $ \boldsymbol {d\sigma_{L}/dt}$ and $\boldsymbol {d\sigma_{T}/dt}$ in $\boldsymbol \pi^{\bf 0}$ deeply virtual electroproduction from the proton

TL;DR

This study performs a Rosenbluth separation of cross sections in deeply virtual $b5^0$ electroproduction from the proton, confirming the dominance of the longitudinal component and supporting factorization at moderate $Q^2$.

Contribution

It provides the first Rosenbluth separation of $b5^0$ DVEP cross sections over a wide $-t$ range, validating the handbag factorization theorem at $Q^2 \\approx 2$ (GeV/c)$^2$.

Findings

Longitudinal contribution dominates the cross section.

$c4_L(t)$ follows a $1/(-t)$ dependence for $-t > 0.5$ (GeV/c)$^2$.

Results agree with previous Hall A data over a wider $-t$ range.

Abstract

We report on a Rosenbluth separation using previously published data by the CLAS collaboration in Hall B, Jefferson Lab for exclusive $\pi^{0}$ deeply virtual electroproduction (DVEP) from the proton at a mean $Q^{2}$ of $\approx$ 2 (GeV/c)$^{2}$. The central question we address is the applicability of factorization in $\pi^0$ DVEP at these kinematics. The results of our Rosenbluth separation clearly demonstrate the dominance of the longitudinal contribution to the cross section. The extracted longitudinal and transverse contributions are in agreement with previous data from Hall A at Jefferson Lab, but over a much wider $-t$ range (0.12 - 1.8 (GeV/c)$^{2}$). The measured dominance of the longitudinal contribution at $Q^{2} \approx$ 2 (GeV/c)$^{2}$ is consistent with the expectation of the handbag factorization theorem. We find that $\sigma_L(t) \sim 1/(-t)$ for $-t >$ 0.5 (GeV/c)$^2$. Determination of both longitudinal and transverse contributions to the deeply virtual $\pi^{0}$ electroproduction cross section allows extraction of additional GPDs.