Time-Dependent Scattering Theory and the Few-Particle Problem.

V.V. Komarov, Anna M. Popova

ANTON Z. CAPRI

The Breakdown of Classical Mechanics Review of Classical Mechanics Elementary Systems One-Dimensional Problems More One-Dimensional Problems Mathematical Foundations Physical Interpretation Distributions and Fourier Transforms Algebraic Methods Central Force Problems Transformation Theory Non-Degenerate Perturbation Theory Degenerate Perturbation Theory Further Approximation Methods Time-Dependent Perturbation Theory Particle in a Uniform Magnetic Field Applications Scattering Theory-Time Dependent Scattering Theory-Time Independent Systems of Identical Particles Quantum Statistical Mechanics.

James G. Glimm, Arthur M. Jaffe

Giampiero V. M. Esposito, Giuseppe Marmo, Gennaro Miele +1 more

Aims and problems of quantum scattering theory Scattering theory is the branch of physics concerned with interacting systems on a scale of time and/or distance that is large compared with the scale of the interaction itself, and it provides the most powerful tool for studying the microscopic nature of the world. In quantum mechanics, a typical scattering process involves a beam of particles prepared with a given energy and with a more or less defined linear momentum. One then studies either the collision with a similar wave packet, or the collision of the given wave packet against a fixed target. In particular, for a two-body elastic scattering problem with conservative forces, we work in the centre of mass frame, hence reducing the original problem to the analysis of a particle in an external field of forces. Indeed, in Section 7.2 we already used such a technique in the investigation of the hydrogen atom. The crucial difference with respect to Section 7.2 is that, in scattering problems, the continuous spectrum and its perturbations are studied, whereas the Balmer formula has to do with bound states. In the following section we outline the basic aspects of what is called time-dependent scattering. Time-dependent scattering The physical situation we would like to study is as follows: a beam of particles is prepared in a state that is approximately free and allowed to evolve towards the scatterer. After the collision we detect the scattered beam far away from the interaction region.

James G. Glimm, Arthur M. Jaffe

N. Hasegawa, K. Hagino, Yusuke Tanimura

It has been known that the time-dependent Hartree-Fock (TDHF) method, or the time-dependent density functional theory (TDDFT), fails to describe many-body quantum tunneling. We overcome this problem by superposing a few time-dependent Slater determinants with the time-dependent generator coordinate method (TDGCM). We apply this method to scattering of two α particles in one dimension, and demonstrate that the TDGCM method yields a finite tunneling probability even at energies below the Coulomb barrier, at which the tunneling probability is exactly zero in the TDHF. This is the first case in which a many-particle tunneling is simulated with a microscopic real-time approach.