5,431 research outputs found
Color Superconductivity and Radius of Quark Star in Extended NJL Model by Using the Dimensional Regularization
A radius of a dense star on the color superconducting phase is investigated
in an extended NJL type model with two flavors of quarks. Since the model is
non-renormalizable, the results depend on the regularization procedure. Here we
apply the dimensional regularization and evaluate the radius of a dense star.
Evaluating the TOV equation, we show the relationship between mass and radius
of the dense star in the dimensional regularization.Comment: 4 pages.To appear in the proceedings of 7th Workshop on Quantum Field
Theory Under the Influence of External Conditions (QFEXT 05), Barcelona,
Catalonia, Spain, 5-9 Sep 2005. References are ad
Influence of QED Corrections on the Orientation of Chiral Symmetry Breaking in the NJL model
We study QED corrections to chiral symmetry breaking in the
Nambu--Jona-Lasinio (NJL) model with two flavors of quarks. In this model, the
isospin symmetry is broken by the differences between the current quark masses
and the electromagnetic charges of the up and down quarks. To leading order in
the 1/N expansion, we calculate the effective potential of the model with
one-loop QED corrections at finite temperature.
Evaluating the effective potential, we study the influence of the isospin
symmetry breaking on the orientation of chiral symmetry breaking.
The current quark mass plays an essential role in maintaining the orientation
of the chiral symmetry breaking.
If the average of the up and down quark masses is small enough, we find a
phase in which the pion field has non-vanishing expectation value and dynamical
CP violation takes place.Comment: 22 pages, 13 figures; added discussion about pion mass differenc
Radiative Symmetry Breaking and Dynamical Origin of Cosmological Constant in Theory with Non-Linear Curvature Coupling
A scalar self-interacting theory non-linearly coupled with some power of the
curvature have a possibility to explain the current smallness of the
cosmological constant. Here one concentrate on a massless scalar field in the
four-dimensional Fridmann-Robertson-Walker (FRW) spacetime with flat spatial
part. One show the phase structure of radiative symmetry breaking and review a
dynamical resolution of the cosmological constant problem.Comment: 9 pages. To appear in the proceedings of 7th Workshop on Quantum
Field Theory Under the Influence of External Conditions (QFEXT 05),
Barcelona, Catalonia, Spain, 5-9 Sep 200
Nambu-Jona-Lasinio Model in Curved Space-Time
The phase structure of Nambu-Jona-Lasinio model with N-component fermions in
curved space-time is studied in the leading order of the 1/N expansion.
The effective potential for composite operator is calculated
by using the normal coordinate expansion in the Schwinger proper-time method.
The existence of the first-order phase transition caused by the change of the
space-time curvature is confirmed and the dynamical mass of the fermion is
calculated as a simultaneous function of the curvature and the four-fermion
coupling constant.
The phase diagram in the curvature and the coupling constant is obtained.Comment: 8 pages, 3 figures not included, uses LaTeX, HUPD-931
Regularization dependence on phase diagram in Nambu-Jona-Lasinio model
We study the regularization dependence on meson properties and the phase
diagram of quark matter by using the two flavor Nambu-Jona-Lasinio model. We
find that the meson properties and the phase structure do not show drastically
difference depending the regularization procedures. We also find that the
location or the existence of the critical end point highly depends on the
regularization methods and the model parameters. Then we think that
regularization and parameters are carefully considered when one investigates
the QCD critical end point in the effective model studies.Comment: 28 page
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