CHIRAL LAGRANGIAN FOR STRANGE HADRONIC MATTER

A generalized Lagrangian for the description of hadronic matter based on the linear SU(3)(L)xSU(3)(R) sigma model is proposed. Besides the b aryon octet, the spin-0 and spin-1 nonets, a gluon condensate associat ed with broken scale invariance is incorporated. The observed values f or the vacuum masses of the baryons and mesons are reproduced. In mean -field approximation, vector and scalar interactions yield a saturatin g nuclear equation of state. We discuss the difficulties and possibili ties to construct a chiral invariant baryon-meson interaction that lea ds to a realistic equation of state. It is found that a coupling of th e strange condensate to nucleons is needed to describe the hyperon pot entials correctly. The effective baryon masses and the appearance of a n abnormal phase of nearly massless nucleons at high densities are exa mined. A nonlinear realization of chiral symmetry is considered, to re tain a Yukawa-type baryon-meson interaction and to establish a connect ion to the Walecka model. [S0556-2813(98)07005-8].