1,304 research outputs found
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 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 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 SYM Theory
We study non planar corrections to the spectrum of operators in the
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 , 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
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