Erlangen 2001 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 21: Theorie III
HK 21.3: Talk
Tuesday, March 20, 2001, 17:00–17:15, B
Pion and Kaon Self-energies in Asymmetric Nuclear Matter — •Norbert Kaiser und Wolfram Weise — Physik-Department, Technische Universität München
We use chiral perturbation theory at finite baryon density to calculate systematically the self-energies of pions and kaons in asymmetric nuclear matter. At the two-loop level we find three types of corrections which go beyond the well-known linear density approximation. These are: 1) relativistic corrections from the pseudovector Born terms, 2) double scattering as given by the chiral meson-baryon interaction vertex and 3) effects induced by the chiral 4-meson vertex with the two virtual mesons being absorbed on the nucleons in the Fermi-sea. The resulting mass-shift for a π− in the center of a heavy nucleus as Pb is Δ mπ−≃ 14 MeV, i.e. somewhat smaller than what is needed to support deeply bound pionic atom-states. The π+ mass-shift in 3H (assuming an effective density of 0.05 fm−3) is Δ mπ+≃ −3 MeV. This is consistent with an analysis of π+-electroproduction from 3He measured at MAMI. Finally, we find a 9% increase of the K+ mass at normal nuclear matter density. This is consistent with the interpretation of the K+/K− yields in heavy ion collisions measured at GSI. Supported in part by GSI