Cross sections and electromagnetic response functions for radiative protoncapture in pd -> He-3+e(+)e(-)

Exclusive differential cross sections of virtual-photon radiative proton ca pture in pd --> He-3 + e(+)e(-) at a proton energy of 190 MeV have been mea sured for the first time. The leptonic-angle dependence of the measured cro ss section is exploited in order to determine the electromagnetic response functions in the time-like region. The data are compared to a relativistic gauge-invariant impulse approximation and a Faddeev calculation. Difference s between theoretical predictions and data are discussed in terms of enhanc ed magnetic radiation possibly originating from virtual Delta excitations. (C) 2000 Elsevier Science B.V. All rights reserved.