Electroproduction ofpπ+π−off protons at0.2<Q2<0.6GeV2and1.3<W<1.57GeV with the CLAS detector

This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process $ep\ensuremath{\rightarrow}{e}^{'}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the as yet unexplored kinematic region of photon virtuality $0.2l{Q}^{2}l0.6$ ${\mathrm{GeV}}^{2}$ and invariant mass of the final hadron system $W$ from 1.3 to 1.57 GeV. For the first time, nine independent one-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 nonresonant 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 kinematic dependencies of the one-fold differential cross sections.