Hadron masses at finite density from the Zimanyi-Moskowski model

The density dependence of hadron masses has been calculated from different versions of the Zimanyi-Moskowski (ZM) model and the results have been compared with the Walecka model. The ZM model has been extended to include pions. The meson masses have been calculated in the random phase approximation self-consistently. The sigma, omega, and pi masses are found to increase with density, as also in the Walecka model; interestingly, it has been found that the abnormal increase of pion mass with density, which is found in the Walecka model, can be avoided in the ZM models.