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.
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.
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.}
118914118
General structure of the photon self-energy in noncommutative QED
We study the behavior of the photon two point function, in noncommutative QED, in a general covariant gauge and in arbitrary space-time dimensions. We show, to all orders, that the photon self-energy is transverse. Using an appropriate extension of the dimensional regularization method, we evaluate the one-loop corrections, which show that the theory is renormalizable. We also prove, to all orders, that the poles of the photon propagator are gauge independent and briefly discuss some other related aspects.
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.
44515091
Thermal Operator Representation of Finite Temperature Graphs II
F. T. Brandt, Ashok Das, Olivier Espinosa, J. Frenkel and Silvana Perez a Instituto de F́ısica, Universidade de São Paulo, São Paulo, BRAZIL b Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627-0171, USA c Departamento de F́ısica, Universidad Técnica Federico Santa Maŕıa, Casilla 110-V, Valparáıso, CHILE and d Departamento de F́ısica, Universidade Federal do Pará, Belém, Pará 66075-110, BRAZIL
17741796
Ward identities for rigid symmetries of higher order
Higher order conservation laws, associated with conserved antisymmetric tensors $j^{\mu_1 ... \mu_k}$ fulfilling $\partial_{\mu_1} j^{\mu_1 ... \mu_k} \approx 0$, are shown to define rigid symmetries of the master equation. They thus lead to independent Ward identities which are explicitly derived.
119057407
Extended antifield formalism
Abstract The antifield formalism is extended so as to incorporate the rigid symmetries of a given theory. To that end, it is necessary to introduce global ghosts not only for the given rigid symmetries, but also for all the higher order conservation laws, associated with conserved antisymmetric tensors j μ 1 3 μ k fulfilling ϖ μ 1 j μ 1 3 μ k 2~ 0. Otherwise, one may encounter obstructions of the type discussed in by the authors. These higher order conservation laws are shown to define additional rigid symmetries of the master equation and to form — together with the standard symmetries — an interesting algebraic structure. They lead furthermore to independent Ward identities which are derived in the standard manner, because the resulting master (“Zinn-Justin”) equation capturing both the gauge symmetries and the rigid symmetries of all orders takes a known form. Issues such as anomalies or consistent deformations of the action preserving some set of rigid symmetries can be also systematically analysed in this framework.
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.
14946872
Antifield dependence of anomalies
Abstract It is shown that generally the consistency equation for anomalies of quantum field theories has solutions which depend nontrivially on the sources of the (generalized) BRS-transformations of the fields. Explicit previously unknown examples of such solutions are given for Yang-Mills and super Yang-Mills theories.
119714464
All consistent Yang-Mills anomalies
Abstract For the case of a compact gauge group we list all solutions to the 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 to the negative.