Chiral condensates and size of the sigma term

摘要

The in-medium chiral condensate is studied with a new approach which has the advantage of no need for extra assumptions on the current mass derivatives of model parameters. It is shown that the pion-nucleon Sigma term is 9/2 times the average current mass of tight quarks, if quark confinement is linear. Considering both perturbative and non-perturbative interactions, the chiral condensate decreases monotonously with increasing densities, approaching to zero at about 4 fm(-3). (C) 2004 Elsevier B.V. All rights reserved.