The chiral condensate in nuclear matter

We investigate the density dependence of the chiral order parameter or quark condensate 〈qq〉 in nuclear matter using relativistic Brueckner-Hartree-Fock theory. While the leading behavior linear in the density is known to be determined model independently by the pion-nucleon sigma term, we demonstrate that higher order corrections are extremely sensitive to the interpretation of the scalar “σ”-meson and its substructure.