Meson loop effect on high density chiral phase transition
  We test the stability of the mean-field solution in the Nambu--Jona-Lasinio model. For stable solutions with respect to both the \sigma and \pi directions, we investigate effects of the mesonic loop corrections of 1/N_c, which correspond to the next-to-leading order in the 1/N_c expansion, on the high density chiral phase transition. The corrections weaken the first order phase transition and shift the critical chemical potential to a lower value. At N_c=3, however, instability of the mean field effective potential prevents us from determining the minimum of the corrected one. 
Tomohiko Sakaguchi (Kyushu Univ.), Kouji Kashiwa (Kyushu Univ.),   Masayuki Matsuzaki (Kyushu Univ. and Fukuoka Univ. of Edu...