Novel soft-photon analysis of ppγ below pion-production threshold

Abstract

A novel soft-photon amplitude is proposed to replace the conventional Low soft-photon amplitude for nucleon-nucleon bremsstrahlung. Its derivation is guided by the standard meson-exchange model of the nucleon-nucleon interaction. This new amplitude provides a superior description of ppγ data. The predictions of this new amplitude are in close agreement with potential-model calculations, which implies that, contrary to conclusions drawn by others, offshell effects are essentially insignificant below pion-production threshold.13.75.Cs, 13.40.-fTypeset using REVT E X 1

Model for bremsstrahlung emission accompanying interactions between protons and nuclei from low energies up to intermediate energies: Role of magnetic emission

“…Here, there have been two directions of intensive investigations: Refs. [61,62] and [63][64][65][66][67][68][69][70][71][72][73][74]. However, the main emphasis in these papers was on construction of a correct relativistic description of the interaction between two nucleons in this task, where formalism was developed in momentum representation mainly.…”

New approach to determine proton-nucleus interactions from experimental bremsstrahlung data

“…The cross sections of the emitted photons have been measured for a long time (see Refs. [1][2][3][4][5][6][7][8][9][10][11]), and different theoretical models and approaches were developed to estimate the emitted photons (for example, see [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]). In particular, the spectra of the emitted photons are dependent on dynamics of the scattering of the proton off the nucleus, which is determined by interactions between the proton and nucleus.…”

Virtual-pion and two-photon production inppscattering

“…The differences between the different versions lie in the particular choice of the on-shell kinematics at which the T-matrix is evaluated. Of particular interest for the discussion in this section is the SPM where the t and u Mandelstam variables are selected to define the on-shell kinematics for the T-matrix [21,22,25], which will be referred to as the tu-SPM hereafter.…”

“…This novel SPM, based on a power-series expansion of the T-matrix, combines ideas of the two SPM's which are frequently used for singlephoton bremsstrahlung in pp scattering: the original SPM [19,20], which is directly inspired by the derivation of the low-energy theorem for bremsstrahlung by Low [18], and a later one proposed in ref. [21], which has been very successful in reproducing the observed cross sections [22,23]. The important distinction of the new SPM from the existing two is that no explicit contact terms, or the so-called internal contributions, need to be introduced.…”