Proton-proton bremsstrahlung and the off-shell behavior of the NN interaction

The ppγ reaction is studied in an effort to better understand the properties of this reaction for probing the off-shell behavior of the NN interaction. Particular emphasis is placed on expressing the NN interaction in terms of its spin-isospin components and investigating the sensitivity of this reaction to these components. It is shown that, overall, this reaction is mostly sensitive to the tensor component of the NN interaction. More specifically, different observables become sensitive to different components of the interaction depending on the proton-scattering angles. Also, the off-shell behavior of different spin-isospin components of different interactions are explicitly exhibited and directly compared with each other. It is shown that the spin observables in ppγ reactions are sensitive enough to distinguish between different interactions provided their off-shell differences in the spin-triplet components are significant. In particular, using the presently available analyzing-power data of the TRIUMF group, the Bonn OBEPT-based interaction can be clearly distinguished from the Paris and Bonn OBEPQ-based interactions in the tensor and central spin-triplet components, where the OBEPT differs from the other potentials by similar 20% in its off-shell behavior. However, the ppγ reaction is not sensitive enough to distinguish the off-shell differences observed in the central spin-singlet component of these interactions. ((orig.))