Speaker
Prof.
Pawel Danielewicz
(NSCL/Cyclotron Laboratory, Michigan State University)
Description
Striving to develop a practical approach for nuclear collisions, based on nonequilibrium Green's functions, we start out by considering collisions of slabs in one dimension, within the mean-field approximation of the Green’s-function method. In the latter case, the dynamics is self-consistently described in terms of a single-particle density-matrix for the colliding system. We concentrate on two issues of importance for the practical reaction simulations: on limiting the amount of information followed when simulating a reaction and on preparing the initial state for a reaction within the same methodology as for simulations. Regarding the second issue, we demonstrate that the mean-field ground-state may be arrived at by adiabatically switching on the mean-field interactions. We hope to be able to do the same for correlated states. Regarding the first issue above, we show that far off-diagonal elements of the density matrix, in the spatial representation, may be suppressed without affecting the evolution close to diagonal of the matrix. Those far-away elements represent entangled wavefunctions of nucleons emerging from a reaction. The growth in redundancy of information, with the progress of a reaction, appears to be closely tied to the expansion of the system. The only aspect of the system, for which the far-away elements appear to be crucial, is the time-reversal symmetry. Within the Wigner representation, the discarding of far-away elements of the matrix is equivalent to momentum smoothing of the Wigner function for the reaction. The findings bode well for the possibility of carrying out full three-dimensional calculations of collisions within the Green's function approach.
Primary authors
Dr
Arnau Rios
(Department of Physics, University of Surrey)
Prof.
Pawel Danielewicz
(NSCL/Cyclotron Laboratory, Michigan State University)
Co-author
Mr
Brent Barker
(NSCL/Cyclotron Laboratory, Michigan State University)
