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HK: Physik der Hadronen und Kerne

HK 38: Theory VI

HK 38.5: Vortrag

Donnerstag, 14. März 2002, 15:00–15:15, C

Chiral Dynamics and Nuclear Matter — •Stefan Fritsch¹, Norbert Kaiser¹, and Wolfram Weise^2,1 — ¹Physik Department der Technischen Universität München, Garching, Germany — ²ECT*, Villazzano (Trento), Italy

We calculate the equation of state of isospin-symmetric nuclear matter in the three-loop approximation of chiral perturbation theory. The contributions to the energy per particle Ē(k_f) from one- and two-pion exchange diagrams are ordered in powers of the Fermi-momentum k_f (modulo functions of k_f /m_π). Already at order O(k_f⁴) two-pion exchange produces realistic nuclear binding. Without inclusion of any further short-range terms the empirical saturation point and nuclear compressibility K≃ 250 MeV are well reproduced at order O(k_f⁵) with a momentum cut-off of Λ≃ 0.65 GeV. In the same framework we calculate the density-dependent asymmetry energy, reproducing its empirical value of A₀≃ 34 MeV. We also evaluate the momentum and density dependent single particle potential of nucleons in isospin-symmetric nuclear matter. The contributions from one- and two-pion exchange diagrams give rise to a potential depth for a nucleon at rest of U(0,k_f0) = −53.2 MeV at saturation density. The momentum dependence of the single particle potential can be translated into a mean effective nucleon mass of M^* ≃ 0.8 M. Finally, we extend our scheme to small non-zero temperatures and observe the liquid–gas phase transition of nuclear matter at T_c≃ 26 MeV and ρ_c≃ 0.5ρ₀.

Work supported in part by BMBF, GSI and DFG.