Critical and tricritical exponents of the Gross-Neveu model in the large-NfN_f limit

The critical and the tricritical exponents of the Gross-Neveu model are calculated in the large-$N_f$ limit. Our results indicate that these exponents are given by the mean-field values.Comment: 8 pages, 8 figure

Fractal extra dimension in Kaluza-Klein theory

Kaluza-Klein theory in which the geometry of an additional dimension is fractal has been considered. In such a theory the mass of an elementary electric charge appears to be many orders of magnitude smaller than the Planck mass, and the "tower" of masses which correspond to higher integer charges becomes aperiodic.Comment: 3 pages, accepted for publication in Phys.Rev.D (submitted on 3.28.2001

Study of the crossover transition of a gas of extended hadrons

We formulate a simple model for a gas of extended hadrons at zero chemical potential by taking inspiration from the compressible bag model. We show that a crossover transition qualitatively similar to lattice QCD can be reproduced by such a system by including some appropriate additional dynamics. Under certain conditions, at high temperature, the system consists of a finite number of infinitely extended bags, which occupy the entire space. In this situation the system behaves as an ideal gas of quarks and gluons.Comment: 2 pages, 1 figure - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

A Two-Dimensional Model with Chiral Condensates and Cooper Pairs Having QCD-like Phase Structure

We describe how a generalization of the original Gross-Neveu model from U(N) to O(N) flavor symmetry leads to the appearance of a pairing condensate at high density, in agreement with the conjectured phenomenon of color superconductivity in $(3+1)$-dimensional QCD. Moreover, the model displays a rich phase structure which closely resembles the one expected in two-flavor QCD.Comment: 11 pages, 1 fugure, Presented at TMU-Yale Symposium on Dynamics of Gauge Fields: An External Activity of APCTP, Tokyo, Japan, 13-15 Dec 199

Evaluating matrix elements relevant to some Lorenz violating operators

Carlson, Carone and Lebed have derived the Feynman rules for a consistent formulation of noncommutative QCD. The results they obtained were used to constrain the noncommutativity parameter in Lorentz violating noncommutative field theories. However, their constraint depended upon an estimate of the matrix element of the quark level operator (gamma.p - m) in a nucleon. In this paper we calculate the matrix element of (gamma.p - m), using a variety of confinement potential models. Our results are within an order of magnitude agreement with the estimate made by Carlson et al. The constraints placed on the noncommutativity parameter were very strong, and are still quite severe even if weakened by an order of magnitude.Comment: 4 pages, 3 figures, RevTex, minor change

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

Titanoclinohumite: A possible mineralogical site for water in the upper mantle

Titanium-rich clinohumite and layered structure minerals are observed in kimberlite and as inclusions in pyropic garnets from the Moses Rock dike, a kimberlite-bearing breccia dike in San Juan County, Utah. Associated clinopyroxenes observed as inclusions within similar pyropes and also in kimberlite are estimated to have equilibrated at depths ranging from about 50 to 150 km at modest temperatures, generally less than 1000°C. The presence of titanoclinohumite, a high-density hydrous phase, is of considerable interest as a possible site for volatiles in the earth's upper mantle. The dehydration of hydrous phases such as titanoclinohumite within the upper mantle (1) may provide water as a free phase, (2) could be important in the genesis of kimberlite and alkali-basalt magma, and (3) may be one means of producing a low-velocity zone in the upper mantle

Induced Magnetic moments in three-dimensional gauge theories with external magnetic fields

We study the appearance of induced parity-violating magnetic moment, in the presence of external magnetic fields, for even-number of fermion species coupled to dynamical fields in three dimensions. Specifically, we use a SU(2)xU(1) gauge model for dynamical gauge symmetry breaking, which is also proposed recently as a field theoretical model for high-temperature superconductors. By decomposing the fermionic degrees of freedom in terms of Landau levels, we show that, in the effective theory with the lowest Landau levels, a parity-violating magnetic moment interaction is induced by the higher Landau levels when the fermions are massive. The possible relevance of this result for a recently observed phenomenon in high-temperature superconductors is also discussed.Comment: 15 pages revtex, one figure incorporated, References added no other change

Bosonic Fields in the String-like Defect Model

We study localization of bosonic bulk fields on a string-like defect with codimension 2 in a general space-time dimension in detail. We show that in cases of spin 0 scalar and spin 1 vector fields there are an infinite number of massless Kaluza-Klein (KK) states which are degenerate with respect to the radial quantum number, but only the massless zero mode state among them is coupled to fermion on the string-like defect. It is also commented on interesting extensions of the model at hand to various directions such as 'little' superstring theory, conformal field theory and a supersymmetric construction.Comment: 17 pages, LaTex 2e, revised version (to appear in Phys. Rev. D