Photoproduction of two charged pions off protons in the resonance region
Abstract
Photoproduction of charged pions pairs off protons is studied within the invariant masses of the final state hadrons from 1.6 to 2.4 GeV at the Thomas Jefferson National Accelerator Facility with the CLAS detector. The total and differential cross sections and spin-density matrix elements are presented for the isobars $p{\ensuremath{\rho}}^{0}(770), \mathrm{\ensuremath{\Delta}}{(1232)}^{++}{\ensuremath{\pi}}^{\ensuremath{-}}$, and $\mathrm{\ensuremath{\Delta}}{(1232)}^{0}{\ensuremath{\pi}}^{+}$. The data are included in the Bonn-Gatchina coupled-channel analysis and provide the information necessary to determine the branching fractions of $N\ensuremath{\rho}(770)$ decays for most known ${N}^{*}$ and ${\mathrm{\ensuremath{\Delta}}}^{*}$ resonances. For the first time, the $N\ensuremath{\rho}$ branching ratios are obtained here from an event-based likelihood to $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}p$.