High-Precision Proton-Proton Bremsstrahlung Measurements below the Pion-Production Threshold

Abstract

An exclusive proton-proton bremsstrahlung measurement has been performed with polarized protons of 190 MeV. Absolute cross sections and analyzing powers have been measured with unprecedented accuracy in a large part of the phase space. The data are compared with state-of-the-art theoretical calculations including higher-order off-shell effects, like the $\ensuremath{\Delta}$ isobar and meson-exchange currents. Surprisingly, the calculations are unable to describe the data in detail.