Responses of quark condensates to the chemical potential

The responses of quark condensates to the chemical potential, as a function of temperature T and chemical potential $\mu ,$ are calculated within the Nambu–Jona-Lasinio (NJL) model. We compare our results with those from the recent lattice QCD simulations [QCD-TARO Collaboration, S. Choe et al., Nucl. Phys. B (Proc. Suppl.) 106, 462 (2002)]. The NJL model and lattice calculations show qualitatively similar behavior, and they will be complimentary ways to study hadrons at finite density. The behavior above $T_c$ requires more elaborated analyses.