dm/dμ in the Nambu--Jona-Lasinio model

Using the Nambu--Jona-Lasinio (NJL) model we study responses of the pion and kaon masses to changes in the chemical potential, $dm/d\mu$, at zero and finite chemical potential. We find that the behavior of $dm/d\mu$ for the pion is quite different from that for the kaon. Our results can give a clue for future studies of $dm/d\mu$ on the lattice.