The Δ-isobar and proton-proton bremsstrahlung

Abstract

We investigate the effects of the A-isobar on proton-proton bremsstrahlung at a beam energy of 280 MeV. We find significant effects on both cross-section and analyzing power.

Sensitivity of pp-bremsstrahlung to meson-exchange currents

“…In addition, we note that the impulse approximation rescatter amplitudes represent a correction of less than 15% to the dominant nucleon-pole contributions, and that this provides a crude measure of the accuracy of the perturbative exchange current amplitudes we include here. In view of the differences between the present approach and that reported in ref [28] the numerical results of the two calculations are fairly similar, at least at the kinematics where comparison is possible.…”

“…First, like [27], we include the ρπγ, ωπγ, ρηγ and ωηγ exchange currents that have been neglected in [28]. Although the ∆ contributions are certainly the largest of the exchange currents, the vector-meson decay contributions are non-negligible when interferences are correctly included.…”

Gauge-invariant formulation ofNN→NNγ

“…For the TRIUMF experiment at 280 MeV, in particular, the dominant ∆ contribution was found to be arising from the γN ∆ transition current, J µ ∆ , in lowest order [18] (a similar result was found in the single-channel approach of Ref. [16]). We point out, however, that the approach reported in Ref.…”

“…[10][11][12]. There are also a number of other microscopic model calculations throughout the 1990s [13][14][15][16][17][18][19][20][21], which are dynamically similar to Refs. [10][11][12], addressing a variety of issues in the N N bremsstrahlung process.…”

“…We mention that in the present work, we follow the convention of Ref. [1,2] for assigning the nucleon angles θ 1 and θ 2 which is just opposite to the one adopted in other studies [12,16,18]. Also, no arbitrary normalization factor of 2/3 to the data points [26] is applied here.…”