Chemical potential response of pseudoscalar meson masses in the Nambu-Jona-Lasinio model

Using the Nambu-Jona-Lasinio (NJL) model we study chemical potential response of the pion and kaon masses as a function of temperature and chemical potential, i.e., partial derivativem/partial derivativemu (T, mu). First, we obtain the responses assuming the vector-axial vector coupling is zero (gv=0). Then, we include a non-zero gv and study the effects of gv on the responses. We find that the behavior of a for the pion is quite different froth that for the kaon. It means that partial derivativem/partial derivativemu is much dependent on the mass difference between the two quarks, i.e., the a and s quarks (or even between the a and d quarks). Our results may give a clue to future studies of partial derivativem/partial derivativemu on the lattice.