7,006 research outputs found
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
Electroweak symmetry breaking in TeV-scale string models
We propose a scenario of the electroweak symmetry breaking by one-loop
radiative corrections in a class of string models with D3-branes at
non-supersymmetric orbifold singularities with the string scale in TeV region.
As a test example, we consider a simple model based on a D3-brane at locally
C^3/Z_6 orbifold singularity, and the electroweak Higgs doublet fields are
identified with the massless bosonic modes of the open string on that D3-brane.
They have Yukawa couplings with three generations of left-handed quarks and
right-handed up-type quarks which are identified with the massless fermionic
modes of the open string on the D3-brane. We calculate the one-loop correction
to the Higgs mass due to the non-supersymmetric string spectrum and
interactions, and qualitatively suggest that the negative mass squared can be
generated. The problems which must be solved to proceed quantitative
calculations are pointed out.Comment: 9 pages, Talk given at 2nd Cairo International Conference on High
Energy Physics (CICHEP II), Cairo, Egypt, 14-17 Jan 200
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