Microscopic cluster model of α + α bremsstrahlung following a Siegert approach

We have recently developed a microscopic cluster model of nucleus-nucleus bremsstrahlung, which takes implicitly account of a part of the meson-exchange current effects, by applying an extension of the Siegert theorem valid for arbitrary photon energy. This model is applied to the α + α bremsstrahlung. The differences between the bremsstrahlung cross sections obtained in the non-Siegert and Siegert approaches are displayed and discussed. The theoretical bremsstrahlung cross sections are compared with experimental measurements. Whereas the agreement with quite old experimental data is fair, a rather important discrepancy between the theoretical results and the more recent experimental data is noticed. Some paths to investigate this disagreement are proposed