Narrow Results

Within the framework of a semiclassical approximation the general theory of calculation of effective currents and sources generating bremsstrahlung of an arbitrary number of soft quarks and soft gluons at collision of a high-energy color-charged particle with thermal partons in a hot quark–gluon plasma is developed. For the case of one- and two-scattering thermal partons with radiation of one or two soft excitations, the effective currents and sources are calculated in an explicit form. In the model case of "frozen" medium, approximate expressions for energy losses induced by the most simple processes of bremsstrahlung of soft quark and soft gluon are derived. On the basis of a conception of the mutual cancellation of singularities in the sum of so-called "diagonal" and "off-diagonal" contributions to the energy losses, an effective method of determining color factors in scattering probabilities containing the initial values of Grassmann color charges is suggested. The dynamical equations for Grassmann color charges of hard particle used by us earlier on are proved to be insufficient for investigation of the higher radiative processes. It is shown that for correct description of these processes the given equations should be supplemented successively with the higher-order terms in powers of the soft fermionic field.

Galactic Cosmic Rays (GCR) entering the Heliosphere are affected by the solar modulation, a combination of diffusion, convection, magnetic drift and adiabatic energy loss usually seen as a decrease in the flux at low energy (less than ~ 10 GeV). We have improved a quasi time-dependent 2D Stochastic Simulation code describing this effects. We focused our attention on the electron modulation, adding energy losses in the Heliosphere that can be neglected for protons and ions: inverse Compton, ionization, synchrotron and bremsstrahlung. These effects have been evaluated in the region affected by the solar magnetic field, up to 100 AU, where the environment conditions are not constant, especially the magnetic field intensity and the photon density. In our calculation the inverse compton energy losses are dominant, but they contribute only a few percent in comparison with the adiabatic losses. We also compared the Local Interstellar Spectrum (LIS) of primary electrons with experimental data collected in the past years at energies ≥ 20 GeV. We found that, inside one standard deviation, LIS fits the data and can be used in a Monte carlo code reproducing CR propagation in the Heliosphere.