Self-interaction effects on screening in three-dimensional QED

We have shown that self interaction effects in massive quantum electrodynamics can lead to the formation of bound states of quark antiquark pairs. A current-current fermion coupling term is introduced, which induces a well in the potential energy profile. Explicit expressions of the effective potential and renormalized parameters are provided

On the nature of fermion-monopole supersymmetry

It is shown that the generator of the nonstandard fermion-monopole supersymmetry uncovered by De Jonghe, Macfarlane, Peeters and van Holten, and the generator of its standard N=1/2 supersymmetry have to be supplemented by their product operator to be treated as independent supercharge. As a result, the fermion-monopole system possesses the nonlinear N=3/2 supersymmetry having the nature of the 3D spin-1/2 free particle's supersymmetry generated by the supercharges represented in a scalar form. Analyzing the supercharges' structure, we trace how under reduction of the fermion-monopole system to the spherical geometry the nonlinear N=3/2 superalgebra comprising the Hamiltonian and the total angular momentum as even generators is transformed into the standard linear N=1 superalgebra with the Hamiltonian to be the unique even generator.Comment: 8 pages, minor extension of concluding comment

The superstring Hagedorn temperature in a pp-wave background

The thermodynamics of type IIB superstring theory in the maximally supersymmetric plane wave background is studied. We compute the thermodynamic partition function for non-interacting strings exactly and the result differs slightly from previous computations. We clarify some of the issues related to the Hagedorn temperature in the limits of small and large constant RR 5-form. We study the thermodynamic behavior of strings in the case of $AdS_3 \times S^3 \times T^4$ geometries in the presence of NS-NS and RR 3-form backgrounds. We also comment on the relationship of string thermodynamics and the thermodynamic behavior of the sector of Yang-Mills theory which is the holographic dual of the string theory.Comment: 22 pages, JHEP style, minor misprints corrected, some comments adde

Space/Time Noncommutativity in String Theories without Background Electric Field

The appearance of space/time non-commutativity in theories of open strings with a constant non-diagonal background metric is considered. We show that, even if the space-time coordinates commute, when there is a metric with a time-space component, no electric field and the boundary condition along the spatial direction is Dirichlet, a Moyal phase still arises in products of vertex operators. The theory is in fact dual to the non-commutatitive open string (NCOS) theory. The correct definition of the vertex operators for this theory is provided. We study the system also in the presence of a $B$ field. We consider the case in which the Dirichlet spatial direction is compactified and analyze the effect of these background on the closed string spectrum. We then heat up the system. We find that the Hagedorn temperature depends in a non-extensive way on the parameters of the background and it is the same for the closed and the open string sectors.Comment: 18 pages, JHEP styl

Supergravity and IOSp(3,1|4) gauge theory

A new formulation of simple D=4 supergravity in terms of the geometry of superspace is presented. The formulation is derived from the gauge theory of the inhomogeneous orthosymplectic group IOSp(3,1|4) on a (4,4)-dimensional base supermanifold by imposing constraints and taking a limit. Both the constraints and the limiting procedure have a clear {\it a priori} physical motivation, arising from the relationship between IOSp(3,1|4) and the super Poincar\'{e} group. The construction has similarities with the space-time formulation of Newtonian gravity.Comment: 17 pages. Expanded version. To appear in Class. Quantum Gra

Entropy of the self-dual string soliton

We compute the entropy and the corresponding central charge of the self-dual string soliton in the supergravity regime using the blackfold description of the fully localized M2-M5 intersection.Comment: 15 pages, 1 figure, harvma

Theta Sectors and Thermodynamics of a Classical Adjoint Gas

The effect of topology on the thermodynamics of a gas of adjoint representation charges interacting via 1+1 dimensional SU(N) gauge fields is investigated. We demonstrate explicitly the existence of multiple vacua parameterized by the discrete superselection variable k=1,...,N. In the low pressure limit, the k dependence of the adjoint gas equation of state is calculated and shown to be non-trivial. Conversely, in the limit of high system pressure, screening by the adjoint charges results in an equation of state independent of k. Additionally, the relation of this model to adjoint QCD at finite temperature in two dimensions and the limit of large N are discussed.Comment: 17 pages LaTeX, 3 eps figures, uses eps

DLCQ String Spectrum from N=2{\cal N}=2 SYM Theory

We study non planar corrections to the spectrum of operators in the ${\mathcal N}=2$ supersymmetric Yang Mills theory which are dual to string states in the maximally supersymmetric pp-wave background with a {\em compact} light-cone direction. The existence of a positive definite discrete light-cone momentum greatly simplifies the operator mixing problem. We give some examples where the contribution of all orders in non-planar diagrams can be found analytically. On the string theory side this corresponds to finding the spectrum of a string state to all orders in string loop corrections.Comment: 35 pages, no figure

Matrix Models of Noncommutative (2d+1) Lattice Gauge Theories

We investigate the problem of mapping, through the Morita equivalence, odd dimensional noncommutative lattice gauge theories onto suitable matrix models. We specialize our analysis to noncommutative three dimensional QED (NCQED) and scalar QED (NCSQED), for which we explicitly build the corresponding Matrix Model.Comment: 13 pages, LaTeX, no Figure

Mean Field Theory of Josephson Junction Arrays with Charge Frustration

Using the path integral approach, we provide an explicit derivation of the equation for the phase boundary for quantum Josephson junction arrays with offset charges and non-diagonal capacitance matrix. For the model with nearest neighbor capacitance matrix and uniform offset charge $q/2e=1/2$, we determine, in the low critical temperature expansion, the most relevant contributions to the equation for the phase boundary. We explicitly construct the charge distributions on the lattice corresponding to the lowest energies. We find a reentrant behavior even with a short ranged interaction. A merit of the path integral approach is that it allows to provide an elegant derivation of the Ginzburg-Landau free energy for a general model with charge frustration and non-diagonal capacitance matrix. The partition function factorizes as a product of a topological term, depending only on a set of integers, and a non-topological one, which is explicitly evaluated.Comment: LaTex, 24 pages, 8 figure