Exclusive Measurements of Virtual Bremsstrahlung in Proton-Proton Scattering at 190 MeV

Abstract

Exclusive differential cross sections of virtual bremsstrahlung in proton-proton scattering below the pion-production threshold have been measured for the first time. The total cross section integrated over photon invariant masses of 15 to $80\mathrm{MeV}/{c}^{2}$ and integrated over the acceptance of the detector is $3.2\ifmmode\pm\else\textpm\fi{}0.1\ifmmode\pm\else\textpm\fi{}0.5\mathrm{pb}$. The data are compared to a low-energy calculation and a fully relativistic microscopic model, which predict a virtual bremsstrahlung cross section of 3.4 and 5.9 pb, respectively. Over the entire experimentally covered phase space, the low-energy calculation gives a better description of the data than the microscopic model.