17629826
Superstring BRST cohomology
We first derive all world-sheet action functionals for NSR superstring models with (1,1) supersymmetry and any number of abelian gauge fields, for gauge transformations of the standard form. Then we prove for these models that the BRST cohomology groups Hg(s), g < 4 (with the antifields taken into account) are isomorphic to those of the corresponding bosonic string models, whose cohomology is fully known. This implies that the nontrivial global symmetries, Noether currents, background charges, consistent deformations and candidate gauge anomalies of an NSR (1,1) superstring model are in one-to-one correspondence with their bosonic counterparts.
118395460
Nonpolynomial gauge invariant interactions of 1-form and 2-form gauge potentials
A four dimensional gauge theory with nonpolynomial but local interactions of 1-form and 2-form gauge potentials is constructed. The model is a nontrivial deformation of a free gauge theory with nonpolynomial dependence on the deformation parameter (= gauge coupling constant).
116908765
Gauge Covariant Algebras and Local BRST Cohomology
The formulation of the local BRST cohomology on infinite jet bundles and its relation and reduction to gauge covariant algebras are reviewed. As an illustration, we compute the local BRST cohomology for geodesic motion in (pseudo-) Riemannian manifolds and discuss briefly the result (symmetries, constants of the motion, consistent deformations).
117843456
All Solutions of the Wess-Zumino Consistency Conditions
For the case of a compact gauge group we list all solutions to the Wess-Zumino consistency equations which have to be satisfied by anomalies. We describe the main algebraic tools and theorems required for this complete classification. Our results answer the question whether in nonrenormalizable gauge theories there exist additional up-to-now unknown anomalies in the negative.
13951212
Anomaly candidates and invariants of D = 4, N = 1 supergravity theories
Anomaly candidates and the form of the most general invariant local action are given for old and new minimal supergravity, including the cases that Yang--Mills and chiral matter multiplets are present. Non-minimal supergravity is also discussed. The results are obtained using BRS techniques by solving the descent equations which contain the consistency equation satisfied by integrands of anomalies and invariant actions. Among the anomaly candidates found there are locally supersymmetric extensions of the well known chiral anomalies as well as previously unknown anomaly candidates.
13550118
New supersymmetric gauge theories: the double tensor multiplet and its interactions
Abstract The double tensor multiplet of D=4 , N=2 supersymmetry, relevant to type IIB superstring vacua, is derived and its gauge invariant and N=2 supersymmetric interactions are analysed, both self-interactions and interactions with vector multiplets and hypermultiplets. Using deformation theory, it is shown that the lowest dimensional nontrivial interaction vertices of this type have dimension 5 and all dimension 5 vertices are determined. They give rise to new N=2 supersymmetric gauge theories of the `exotic' type which are local but nonpolynomial in some of the fields and coupling constants. Explicit examples of such models are constructed.
119404380
On the free energy of noncommutative quantum electrodynamics at high temperature
Abstract We compute higher order contributions to the free energy of noncommutative quantum electrodynamics at a nonzero temperature T . Our calculation includes up to three-loop contributions (fourth order in the coupling constant e ). In the high temperature limit we sum all the ring diagrams and obtain a result which has a peculiar dependence on the coupling constant. For large values of e θ T 2 ( θ is the magnitude of the noncommutative parameters) this nonperturbative contribution exhibits a nonanalytic behavior proportional to e 3 . We show that above a certain critical temperature, there occurs a thermodynamic instability which may indicate a phase transition.
16421434
The energy of the high-temperature quark-gluon plasma
Abstract For the quark-gluon plasma, we study the energy-momentum tensor corresponding to the high-temperature Braaten-Pisarski effective action. The tensor is defined by considering the interaction of the plasma with a weak gravitational field. It is first calculated to second order in g (the QCD coupling constant). Then, by exploiing local invariance, we write down the complete effective action in curved space. From this we infer the energy tensor to all orders in g . For definiteness, we write this in retarded form. Finally, we discuss positivity of T 00 to second order in g .
119048914
The Static effective action for noncommutative QED at high temperature
In this paper, we systematically study the effective action for non-commutative QED in the static limit at high temperature. When $\theta p^{2}\ll 1$, where $\theta$ represents the magnitude of the parameter for non-commutativity and $p$ denotes a typical external three momentum, we show that this leads naturally to a derivative expansion in this model. The study of the self-energy, in this limit, leads to nontrivial $\theta$ dependent corrections to the electric and magnetic masses, which exist only above a certain critical temperature. The three point and the four point amplitudes are also studied as well as their relations to the Ward identities in this limit. We determine the closed form expression for the current involving only the spatial components of the gauge field and present the corresponding static effective action, which is gauge invariant.
119728198
Open and Closed Superstring Five-Point Amplitudes at Tree-Level
In this contribution the tree-level effective actions for gluons and gravitons, as derived from Open and Closed Superstring theories, are reviewed respectively. As known for a long time, at zero order in α′ (the string fundamental constant) the first action is pure Yang-Mills while the second one is pure Einstein-Hilbert. The first Superstring Theory corrections turn up to appear at order in the first case while they appear at in the second one, as known from the three and four-point scattering amplitudes for gluons and gravitons, respectively. Recent work involving the order contributions to the Yang-Mills action is reviewed with some detail, including the authors' present line of research. Also, the uncharted territory of five graviton scattering is commented, looking forward to derive the Superstring Theory corrections to the Einstein-Hilbert action.
16723250
Generalized forward scattering amplitudes in QCD at high temperature
We extend to a general class of covariant gauges an approach which relates the thermal Green functions to forward scattering amplitudes of thermal particles. A brief discussion of the nontransversality of the thermal gluon polarization tensor is given in this context. This method is then applied to the calculation of the ln(T) contributions associated with general configurations of two- and three-point gluon functions. The results are Lorentz covariant and have the same structure as the ultraviolet divergent contributions which occur at zero temperature. {copyright} {ital 1997} {ital The American Physical Society}