119081024
Thermal one- and two-graviton Green's functions in the temporal gauge
momentum, we obtain the leading T 4 as well as the subleading T 2 and log(T) contributions to the graviton self-energy. The gauge fixing independence of the leading T 4 terms as well as the Ward identity relating the self-energy with the one-point function are explicitly verified. We also verify �
35897734
Nonlinear couplings and tree amplitudes in gauge theories.
Following a remark advanced by Feynman, we study the connection between the form of the nonlinear vertices involving gauge particles and the Abelian gauge invariance of physical tree amplitudes. We show that this requirement, together with some natural assumptions, fixes uniquely the structure of the Yang-Mills theory. However, the constraints immposed by the above property are not sufficient to single out the gauge theory of gravitation. {copyright} {ital 1996 The American Physical Society.}
119875841
Cancellation of soft interactions with spectators in the Drell-Yan process
Abstract We verify by explicit calculation, to 2-loop order, the cancellation of soft interactions with spectators in the Drell-Yan process. We employ a model in which a “meson” consists of a parton and a spectator parton, each moving along parallel eikonal lines. The process occurs in the collision of two such “mesons” at velocities near the speed of light. The calculation is sensitive to gluons with wavelengths of the order of or greater than the meson size.
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.
43000553
Multiparticle tree amplitudes in scalar field theory.
Following an argument advanced by Feynman, we consider a method for obtaining the effective action which generates the sum of tree diagrams with external physical particles. This technique is applied, in the unbroken \ensuremath{\lambda}${\mathrm{\ensuremath{\varphi}}}^{4}$ theory, to the derivation of the threshold amplitude for the production of n scalar particles by n initial particles. The leading contributions to the tree amplitude, which become singular in the threshold limit, exhibit a factorial growth with n. \textcopyright{} 1996 The Physical Society.
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.
120544924
Completeness and Nontriviality of the Solutions of the Consistency Conditions
Abstract For the case of a compact gauge group we determine all solutions to the consistency conditions. In particular, our results imply that the known list of anomalies is complete also for nonrenormalizable models.
15245043
Seiberg-Witten maps and noncommutative Yang-Mills theories for arbitrary gauge groups
Seiberg-Witten maps and a recently proposed construction of noncommutative Yang-Mills theories (with matter fields) for arbitrary gauge groups are reformulated so that their existence to all orders is manifest. The ambiguities of the construction which originate from the freedom in the Seiberg-Witten map are discussed with regard to the question whether they can lead to inequivalent models, i.e., models not related by field redefinitions.
17958246
Seiberg-Witten Maps and Anomalies in Noncommutative Yang-Mills Theories
A BRST-cohomological analysis of Seiberg-Witten maps and results on gauge anomalies in noncommutative Yang-Mills theories with general gauge groups are reviewed.
119069136
Local BRST cohomology and Seiberg-Witten maps in noncommutative Yang-Mills theory
Abstract We analyze in detail the recursive construction of the Seiberg–Witten map and give an exhaustive description of its ambiguities. The local BRST cohomology for noncommutative Yang–Mills theory is investigated in the framework of the effective commutative Yang–Mills type theory. In particular, we show how some of the conformal symmetries get obstructed by the noncommutative deformation.
1329783
Seiberg-Witten maps in the context of the antifield formalism
The formulation of Seiberg-Witten maps from the point of view of consistent deformations of gauge theories in the context of the Batalin-Vilkovisky antifield formalism is reviewed. Some additional remarks on noncommutative Yang-Mills theory are made.