Antikaons and hyperons in nuclear matter with saturation

TL;DR

This paper uses a covariant many-body approach based on chiral SU(3) dynamics to study antikaons and hyperons in nuclear matter, revealing significant medium effects, mass shifts, and potential for exotic states and antikaon condensation.

Contribution

It introduces a novel subtraction scheme to avoid singularities and medium divergences, providing new insights into hyperon and antikaon spectral functions in nuclear matter.

Findings

Antikaon spectral functions become narrower at small momenta.

Mass shifts of about 30-40 MeV for Lambda(1405) and Sigma(1385).

Possible formation of exotic strangeness-rich systems and antikaon condensation at moderate densities.

Abstract

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.