"Fluctuations of the Chiral Condensate and Quasi-quark Spectra near Chiral Transition"

We investigate the quasi-quark spectrum near chiral transition at finite temperature. The effects of the precursory soft modes of the phase transition on the quark spectrum are focused. It is found that there appear novel excitation spectra of quasi-quarks and quasi-antiquarks with a three-peak structure. We show that the new spectra originate from the mixing between a quark (anti-quark) and an anti-quark hole (quark hole) caused by a "resonant scattering" of the quasi-quarks with the thermally-excited soft modes which have a small but finite excitation energy at zero momentum. It is also shown that such a spectrum can be seen in a massless fermion spectrum coupled to a massive scalar boson via the Yukawa coupling at finite temperature. Finally effects of the fluctuations on the dilepton production are discussed.