776 research outputs found
Critical and tricritical exponents of the Gross-Neveu model in the large- limit
The critical and the tricritical exponents of the Gross-Neveu model are
calculated in the large- limit.
Our results indicate that these exponents are given by the mean-field values.Comment: 8 pages, 8 figure
Instantons And Baryon Mass Splittings in the MIT Bag Model
The contribution of instanton-induced effective inter-quark interactions to
the baryon mass splittings was considered in the bag model. It is found that
results are different from those obtained in the constituent quark model where
the instanton effects are like those from one-gluon exchange. This is because
in the context of the bag model calculation the one-body instanton-induced
interaction has to be included.Comment: 23 pages, report ZTF-93/10 (to appear in Phys.Rev. D
Instantons in non-Cartesian coordinates
The explicit multi-instanton solutions by 'tHooft and Jackiw, Nohl & Rebbi
are generalized to curvilinear coordinates. The idea is that a gauge
transformation can notably simplify the expressions obtained after the change
of variables. The gauge transform generates a compensating addition to the
gauge potential of pseudoparticles. Singularities of the compensating field are
irrelevant for physics but may affect gauge dependent quantities.Comment: 10 pages, LaTeX, talk given at Quarks-2000 (Pushkin, Russia) and
E.S.Fradkin (Moscow, Russia) conference
The Cheshire Cat Bag Model: Color Anomaly and Properties
We show that color can leak from a QCD bag if we allow for pseudoscalar
isoscalar singlet () coupling at the surface. To enforce total
confinement of color an additional boundary term is suggested. New relations
between the mass and decay constant and the QCD gluon condensates are
derived and compared with the empirical parameters.Comment: 7 pages, LaTeX, Nordita - 92/68
Optimal eigenvalues estimate for the Dirac operator on domains with boundary
We give a lower bound for the eigenvalues of the Dirac operator on a compact
domain of a Riemannian spin manifold under the \MIT bag boundary condition.
The limiting case is characterized by the existence of an imaginary Killing
spinor.Comment: 10 page
Crystalline ground state in chiral Gross-Neveu and Cooper pair models at finite densities
We study the possibility of spatially non-uniform ground state in
(1+1)-dimensional models with quartic fermi interactions at finite fermion
densities by introducing chemical potential \mu. We examine the chiral
Gross-Neveu model and the Cooper pair model as toy models of the chiral
symmetry breaking and the difermion pair condensates which are presumed to
exist in QCD. We confirm in the chiral Gross-Neveu model that the ground state
has a crystalline structure in which the chiral condensate oscillates in space
with wave number 2\mu. Whereas in the Cooper pair model we find that the vacuum
structure is spatially uniform. Some discussions are given to explain this
difference.Comment: 18 pages, REVTeX, 3 eps figure
Calculation of the expansion rate of the three-volume measure in high-energy heavy-ion collisions
In ultrarelativistic heavy-ion collisions the local three-volume measure is
expanding in the longitudinal and transverse directions. This is similar to the
Hubble-expansion of the universe, except that the former is not locally
isotropic. As an example the expansion rate is calculated assuming that the
energy-momentum tensor in the central region is that of an ideal fluid,
undergoing Bjorken flow in longitudinal direction, and with initial conditions
as expected for BNL-RHIC energy. While the longitudinal expansion of
three-volume is independent of the energy density of the fluid, in case of 3+1
dimensional expansion the form of the hydrodynamical solution (rarefaction wave
or deflagration shock) affects the three-volume expansion rate on the
hadronization hypersurface. As a consequence the average expansion rate on that
surface depends on the transverse size of the system. This may reflect in an
impact-parameter dependence of the formation probability of light nuclei and of
the freeze-out temperature of the strong interactions in the system.Comment: 10 Pages REVTEX, 4 Figures; Title slightly modified, 2 new figure
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