Berlin 2008 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 27: Quantum chaos II

DY 27.7: Vortrag

Donnerstag, 28. Februar 2008, 16:00–16:15, MA 004

Level Density of a Fermi Gas: Average Growth and Fluctuations — •Roccia Jerome¹ and Leboeuf Patricio² — ¹Institut für Theoretische Physik, Universität Regensburg D-93040 Regensburg, Germany — ²Laboratoire de Physique Théorique et Modèles Statistiques bâtiment 100 Université Paris-Sud centre scientifique d’Orsay 15 rue Georges Clémenceau 91405 Orsay cedex, France

We investigate the many-body level density ρ_MB for fermions. We establish its behavior as a function of the temperature and the number of particules. We propose a semiclassical expression of ρ_MB for two types of particules with an angular momentum. It is decomposed into a smooth part coming from the saddle point method plus corrective terms due to the expansion of the number of partitions for two types of particles and an oscillating part coming from the fluctuations of the single-particle level density. Our model is validated by a numerical study. For the case of the atomic nucleus, the oscillating part of ρ_MB is controled by a temperature factor which depends on the chaotic or integrable nature of the system and depends on the fluctuation of the ground state energy. This leads to consider in more detail this last quantity. For an isolated system, we give the general expression of the mean value for fixed potentials. We treat the self-bound system case through the example of the three dimensional harmonic oscillator (3DHO).