Self-consistent antikaon dynamics in isospin-asymmetric nuclear medium

We investigate properties of antikaons and hyperon resonances in isospin-asymmetric nuclear medium, using a self-consistent, covariant scheme based on vacuum antikaon-nucleon scattering amplitude.Comment: 9 pages, 5 figures, uses budapest.sty (included);to be published in the Proceedings of the Budapest'2002 Workshop on Quark and Hadron Dynamics, Budapest, Hungary, 3-7 March 200

Kaon and antikaon properties in cold nuclear medium

We present results of a self-consistent calculation for the kaon and antikaon spectral functions in cold nuclear matter, using as input the kaon-nucleon and antikaon-nucleon scattering amplitudes of the vacuum. We investigate the effect of in-medium pion dressing on the antikaon-nucleon scattering amplitudes and antikaon spectral function. We find the influence of pion dressing to be minor on the antikaon spectral function and limited on the hyperon resonances causing only a small additional broadening. An exception is the \Sigma(1690). At nuclear saturation density an attractive mass shift of about 20 MeV and width of about 130 MeV is obtained. The kaon shows a repulsive mass increase of 36 MeV and a small width of the quasiparticle peak at saturation density.Comment: 8 pages, 4 figures, submitted to Heavy Ion Physic

Pions in isospin asymmetric matter and nuclear Drell-Yan scattering

Using a self-consistent delta-hole model the pion propagation in isospin asymmetric nuclear matter is studied. In neutron-rich matter, corresponding to heavy nuclei, a significant difference in positive and negative pion light-cone distributions is obtained leading to a nuclear enhancement of up antiquark distribution compared to the down antiquark one. This means that the sea-quark asymmetry in the free nucleon cannot be extracted model independently from an experiment on a neutron-rich nucleus.Comment: 10 pages, 3 figures (included), Latex 2.09, uses elsart.sty, epsf.st

Open-charm systems in cold nuclear matter

We study the spectral distributions of charmed meson with $J^P=0^-$ quantum numbers in cold nuclear matter applying a self-consistent and covariant many-body approach established previously for the nuclear dynamics of kaons. At leading orders the computation requires as input the free-space two-body scattering amplitudes only. Our results are based on the s-wave meson-nucleon amplitudes obtained recently in terms of a coupled-channel approach. The amplitudes are characterized by the presence of many resonances in part so far not observed. This gives rise to an intriguing dynamics of charmed mesons in nuclear matter. At nuclear saturation density we predict a pronounced two-mode structure of the $D^+$ mesons with a main branch pushed up by about 32 MeV. The lower branch reflects the coupling to two resonance-hole states that are almost degenerate. For the $D^-$ we obtain a single mode pushed up by about 18 MeV relative to the vacuum mode. Most spectacular are the results for the $D^+_s$ meson. The presence of an exotic resonance-hole state gives rise to a rather broad and strongly momentum dependent spectral distribution.Comment: 11 pages, 3 figure

Chiral symmetry, strangeness and resonances

We review the important role played by the chiral SU(3) symmetry in predicting the properties of antikaons and hyperon resonances in cold nuclear matter. Objects of crucial importance are the meson-baryon scattering amplitudes obtained within the chiral coupled-channel effective field theory. The formation of baryon resonances as implied by chiral coupled-channel dynamics is discussed. Results for antikaon and hyperon-resonance spectral functions are presented for isospin symmetric and asymmetric matter.Comment: invited talk presented by M.F.M.L. at the 18th Nishinomiya Yukawa Memorial Symposium, 21 pages, 12 figure