CONSISTENT MESON-FIELD-THEORETICAL DESCRIPTION OF PP BREMSSTRAHLUNG

A parameter-free and relativistic extension of the RuhrPot meson-baryo n model is used to define the dominant isoscalar meson-exchange curren ts. We compute pp-bremsstrahlung observables below the pi-production t hreshold using a relativistic hadronic current density that includes i mpulse, wave function reorthonormalization, meson-recoil, (N) over bar N creation and annihilation, rho pi gamma + omega pi gamma + rho eta gamma + omega eta gamma vector-meson decay, and N Delta gamma(pi,rho) exchange currents. We obtain a good description of the available data. The N Delta gamma(pi) current is shown to dominate the large two-body contributions and closed-form expressions for various nonrelativistic approximations are analyzed. An experimental sensitivity to the admix ture of pseudoscalar and pseudovector admixture of the NN pi interacti on is demonstrated. We examine the Lorentz invariance of the NN revers ible arrow NN t matrices and show a dominantly pseudovector NN pi coup ling renders impulse approximation calculations without boost operator s to be essentially exact. Conversely, a similar analysis of the Delta N reversible arrow NN transitions shows that boost operators and the two-body N Delta gamma wave function reorthonormalization meson-recoil currents are required in NN, Delta N, and Delta Delta coupled channel t-matrix applications. The need for additional data is stressed.