Seminarium Fizyki Jądra Atomowego

Simple observables such as the number of particles might be difficult to describe when a quantum composite system encounters a violent perturbation, such as collisions of atomic nuclei. Our goal is rather simple: counting the number of transfered particles in such a collision. To keep the amount of work for the physicist and his computer to a reasonable level, approximations are considered rather than solving the full Schrödinger equation. The Balian-Veneroni variational principle provides a useful theoretical framework to build dynamical microscopic models. To solve this variational principle, one has to choose one particular type of observable of interest. For expectation values of one-body operators, like the average number of transferred particles, this leads to the time-dependent Hartree-Fock (TDHF) theory. For their fluctuations, however, we need to include come correlations by solving an equation equivalent to the time-dependent RPA. In nuclear physics, the range of applications of these approaches is quite large, from sub-barrier heavy-ion reactions to more violent deep-inelastic collisions.