Electroproduction of p \pi^{+} \pi^{-} off protons at 0.2<Q^{2}<0.6 GeV^{2} and 1.3<W<1.57 GeV with CLAS

TL;DR

This study provides comprehensive measurements of the $e p o e' p \pi^{+} \pi^{-}$ process in a new kinematic region, revealing the dominant reaction mechanisms and sensitivity to specific nucleon resonances.

Contribution

First detailed differential cross sections for this process in the specified kinematic range, enabling analysis of reaction mechanisms and resonance contributions.

Findings

Non-resonant mechanisms dominate the cross sections.

Sensitivity to $N(1440)P_{11}$ and $N(1520)D_{13}$ resonances.

First-time measurement of nine independent differential cross sections.

Abstract

This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process $e p \to e' p \pi^{+} \pi^{-} $. The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the so-far unexplored kinematic region of photon virtuality 0.2 $<$ $Q^{2}$ $<$ 0.6 GeV$^{2}$ and invariant mass of the final hadron system $W$ from 1.3 to 1.57 GeV. For the first time, nine independent 1-fold differential cross sections were determined in each bin of $W$ and $Q^{2}$ covered by the measurements. A phenomenological analysis of the data allowed us to establish the most significant mechanisms contributing to the reaction. The non-resonant mechanisms account for a major part of cross-sections. However, we find sensitivity to s-channel excitations of low-mass nucleon resonances, especially to the $N(1440)P_{11}$ and $N(1520)D_{13}$ states in kinematical dependencies of the 1-fold differential cross-sections.