Anomalous magnetic moment contributions to NN bremsstrahlung in the soft-photon approximation

• Main Authors: Gibson, B F, Penninga, T D, Timmermans, R G E, Liou, M K
• Format: Conference Proceeding
• Language: English
• Subjects: AMPLITUDES; BREMSSTRAHLUNG; COMPARATIVE EVALUATIONS; CROSS SECTIONS; NEUTRONS; NUCLEAR MAGNETIC MOMENTS; NUCLEAR PHYSICS AND RADIATION PHYSICS; PHOTON EMISSION; PHOTON-NUCLEON INTERACTIONS; PHOTONS; PROTON-NEUTRON INTERACTIONS; PROTON-PROTON INTERACTIONS; PROTONS; RELATIVISTIC RANGE
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.1932888

The soft photon approximation (SPA), which is relativistic and based upon a fundamental theorem for photon emission, is applied to explore two separate nucleon-nucleon bremsstrahlung (NN) processes: pp and np. They are examined together in an effort to understand the mechanism which governs photon emission from these basic two-nucleon systems. In this investigation we focus upon the effect of the anomalous magnetic moments of the proton (p) and the neutron (n). In our SPA calculation we use the standard Low amplitude MmuLow{expression} as derived by Nyman plus the more recently developed amplitude MmuTuTts{expression}, referred to as the two-u-two-t special (TuTts) amplitude. The amplitude MmuTuTts{expression} is identical to the amplitude MmuLow{expression} through order K0 in the soft-photon expansion. However, MmuTuTts{expression} includes an additional term Mmu(3){expression}(K1; ) (plus higher order terms). The term Mmu(3){expression}(K1; ) is of order K1 in the soft-photon expansion and it is a function of p and n. Using the amplitudes MmuTuTts{expression} and MmuLow{expression}, we have calculated pp and np cross sections as a function of photon angle with and without contributions from p and n. Comparison with available pp data has been made; in particular, the contribution from Mmu(3){expression}(K1; ) has been investigated. Results will be presented and discussed which relate to the following: (i) The anomalous magnetic moment effect is significant in pp; however, it is small in np. That is, the two amplitudes MmuTuTts{expression} and MmuLow{expression} yield very similar np cross sections, but they predict very different pp cross sections. (ii) MmuTuTts{expression} appears to provide a better SPA than MmuLow{expression} in the case of pp. Because p terms dominate the pp cross section, the contribution from Mmu(3){expression}(K1; ) is important. Clearly, Mmu(3){expression}(K1; ) makes a significant difference. (iii) The reason why MmuTuTts{expression} and MmuLow{expression} predict similar np cross sections will be analyzed and discussed.