120504956
Weak boson plus jet production in 2nd-order QCD
AbstractWe calculate cross sections for the production ofW+ andZ bosons in association with 1 and 2 jets at
$$p\bar p$$
 collider energies. The expected rates for these processes in second-order QCD are presented as a function of the cuts on the transverse momenta of the jets and are compared with jet rates measured by UA1.
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
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.
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).
115177706
Supersymmetry algebra cohomology. II. Primitive elements in 2 and 3 dimensions
The primitive elements of the supersymmetry algebra cohomology as defined in a companion paper are computed exhaustively for standard supersymmetry algebras in dimensions D = 2 and D = 3, for all signatures (t, D − t) and all numbers N of sets of supersymmetries.
10977212
Exotic gauge theories from tensor calculus
We construct non-standard interactions between exterior form gauge fields by gauging a particular global symmetry of the Einstein-Maxwell action for such fields. Furthermore, we discuss generalizations of such interactions by adding couplings to gravitational Chern-Simons forms and to fields arising through dimensional reduction. The construction uses an appropriate tensor calculus.
16432367
Jet Coordinates for Local BRST Cohomology
The construction of appropriate jet space coordinates for calculating local BRST cohomology groups is discussed. The relation to tensor calculus is briefly reviewed too.
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.