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Towards asymptotic completeness in massless quantum field theory

Wojciech De Roeck
Fredag, 9 december, 2011, at 14:15-15:15, in Aud. G2 (1532-122)
 It is widely believed that an atom interacting with the electromagnetic field (with total initial energy well-below the ionization threshold) relaxes to its ground state while its excess energy is emitted as radiation. Hence, for large times, the  state of the atom+field system should consist of  the atom in its ground state, and a few free photons that travel off to spatial infinity.   Mathematically, this picture is captured by the notion of 'asymptotic completeness'. Despite some recent progress on the spectral theory of such systems, a proof of relaxation to the ground state and asymptotic completeness  was/is still missing, except in some special cases (massive photons, small perturbations of harmonic potentials). In a simplified setup, where the atom is modelled by a finite-level system, we very recently (arXiv:1109.5582 <http://arxiv.org/abs/1109.5582>) proved approach to the ground state, and we are currently trying to get the asymptotic completeness as well.

Kontaktperson: Jacob Schach Møller