Spin-Isospin Modes in Heavy-Ion Collisions I: Nuclear Matter at Finite   Temperatures
  With a view towards implementation in microscopic transport simulations of heavy-ion collisions, the properties of spin-isospin modes are studied in nuclear matter consisting of nucleons and Delta isobars that interact by the exchange of pi and rho mesons. For a standard p-wave interaction and an effective g' short-range interaction, the dispersion relations for the spin- isospin modes, and the associated amplitudes, are calculated at various nuclear densities and temperatures, within the random-phase approximation. Quantities of physical interest are then extracted, including the total and partial Delta decay widths and the Delta cross sections in the nuclear medium. The self-consistent inclusion of the Delta width has a strong effect on the Delta cross sections at twice normal nuclear density, as compared with the result of ignoring the width. Generally, the obtained quantities exhibit a strong density dependence, but are fairly insensitive to the temperature, at least up to T=25 MeV. Finally, it is described how these in-medium effects may be consistently included into microscopic transport simulations of nuclear collisions, and the improvements over previous approaches are discussed. 
J. Helgesson and J. Randrup (Lawrence Berkeley Lab, Berkeley, USA)