Quasiparticle picture of quarks near chiral transition at finite temperature

We investigate, using a chiral effective model, the quark spectrum in the critical region of the chiral transition focusing on the effect of the possible mesonic excitations in the quark-gluon plasma phase. We find that there appears a novel three-peak structure in the quark spectra. We elucidate the mechanism of the appearance of the multi-peak structure with the help of a Yukawa model with an elementary boson.Comment: 4 pages, 5 eps figures, to appear in the proceedings of International Conference on Strong & Electroweak Matter 2006, Brookhaven National Laboratory, USA, May 10-13, 200

Spectral Properties of Quarks at Finite Temperature in Lattice QCD

We analyze the quark spectral function above and below the critical temperature for deconfinement and at finite momentum in quenched lattice QCD. It is found that the temporal quark correlation function in the deconfined phase near the critical temperature is well reproduced by a two-pole ansatz for the spectral function. The bare quark mass and momentum dependences of the spectral function are analyzed with this ansatz. In the chiral limit we find that even near the critical temperature the quark spectral function has two collective modes corresponding to the normal and plasmino excitations in the high temperature (T) limit. The pole mass of these modes at zero momentum, which should be identified to be the thermal mass of the quark, is approximately proportional to T in a rather wide range of T in the deconfined phase.Comment: 4 pages, 2 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

Mass Generation Mechanism in Supersymmetric Composite Model with Three Generations

We propose a supersymmetric composite model with three generations in which supersymmetry and electroweak symmetry are broken dynamically, and masses of quarks and leptons are generated without introducing any mass scales by hand. All the mass scales in the model are expected to be generated dynamically. The mechanism to have mass hierarchy is explicitly described, although the roughly estimated mass spectrum of quarks and leptons does not exactly coincide with the realistic one.Comment: 15 pages, 2 figure

Vertex Operators in IIB Matrix Model

The vertex operators for the supergravity multiplet can be constructed through the Wilson lines in IIB matrix model. We investigate the structure of the vertex operators and the symmetry of their correlation functions. For this purpose, we perturb the theory by the Wilson lines dual to the supergravity multiplet. The structure of the Wilson lines can be determined by requiring $\cal{N}$=2 SUSY under the low energy approximation. We argue that the generating functional of the correlators is invariant under local SUSY transformations of IIB supergravity.Comment: 21 pages; references adde