We evaluate the antikaon spectral density in isospin symmetric nuclear matter. The in-medium antikaon-nucleon scattering process and the antikaon propagation is treated in a self consistent and relativistic manner where a maximally schemeindependent formulation is derived by performing a partial density resummation in terms of the free-space antikaon-nucleon scattering amplitudes. The latter amplitudes are taken from a covariant and chiral coupled-channel SU(3) approach which includes s-, p-and d-waves systematically. Particular care is taken on the proper evaluation of the in-medium mixing of the partial waves. Our analysis establishes a rich structure of the antikaon spectral function with considerable strength at small energies. At nuclear saturation density we predict attractive mass shifts for the Λ(1405), Σ(1385) and Λ(1520) of about 60 MeV, 60 MeV and 100 MeV respectively. The hyperon states are found to exhibit at the same time an increased decay width of about 120 MeV for the s-wave Λ(1405), 70 MeV for the p-wave Σ(1385) and 90 MeV for the d-wave Λ(1520) resonance.
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
In this talk we review recent progress on the systematic evaluation of the kaon and antikaon spectral functions in dense nuclear matter based on a chiral SU(3) description of the low-energy pion-, kaon-and antikaon-nucleon scattering data.
We evaluate the antikaon and hyperon spectral functions in a self-consistent
and covariant many-body approach. The computation is based on coupled-channel
dynamics derived from the chiral SU(3) Lagrangian. A novel subtraction scheme
is developed that avoids kinematical singularities and medium-induced power
divergencies all together. Scalar and vector mean fields are used to model
nuclear binding and saturation. The effect of the latter is striking for the
antikaon spectral function that becomes significantly more narrow at small
momenta. Attractive mass shifts of about 30 and 40 MeV are predicted for the
Lambda(1405) and Sigma(1385) resonances. Once scalar and vector mean fields for
the nucleon are switched on the Lambda(1520) resonances dissolves almost
completely in nuclear matter. All together only moderate attraction is
predicted for the nuclear antikaon systems at saturation density. However, at
larger densities we predict a sizable population of soft antikaon modes that
arise from the coupling of the antikaon to a highly collective Lambda(1115)
nucleon-hole state. This may lead to the formation of exotic nuclear systems
with strangeness and antikaon condensation in compact stars at moderate
densities.Comment: 49 pages, 13 figures, The revised manuscript contains additional
material at twice nuclear saturation density. An unexpected and novel
mechanism is unravelled that may have dramatic implications on the formation
of exotic nuclear systems with strangeness and antikaon condensation in
compact star
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