123449527
Cancellation of spectator interactions in the Drell-Yan and deep inelastic processes
We present an explicit calculation of the one-gluon soft interactions involving one spectator quark in the Drell-Yan and in the deep inelastic processes. We verify that these interactions are suppressed in the high energy limit. The gluon has a wavelength ranging from infinity to a value that is much smaller than the wavelength of the high energy photon. This includes a subregion, ranging from the meson size to values much bigger than the meson size, that has not been explicitly considered in the previous calculations.
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.
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
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.
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.}
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.
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.
16321193
Structure of BRS-Invariant Local Functionals
For a large class of gauge theories a nilpotent BRS-operator $s$ is constructed and its cohomology in the space of local functionals of the off-shell fields is shown to be isomorphic to the cohomology of $\4s=s+d$ on functions $f(\4C,\PH)$ of tensor fields $\PH$ and of variables $\4C$ which are constructed of the ghosts and the connection forms. The result allows general statements about the structure of invariant classical actions and anomaly candidates whose BRS-variation vanishes off-shell. The assumptions under which the result holds are thoroughly discussed.
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).
118158206
Aspects of supersymmetric BRST cohomology
The application and extension of well-known BRST cohomological methods to supersymmetric field theories are discussed. The focus is on the emergence and particular features of supersymmetry algebra cohomology in this context. In particular it is discussed and demonstrated that supersymmetry algebra cohomology emerges within the cohomological analysis of standard supersymmetric field theories whether or not the commutator algebra of the symmetry transformations closes off-shell.
16423561
Covariant theory of asymptotic symmetries, conservation laws and central charges
Under suitable assumptions on the boundary conditions, it is shown that there is a bijective correspondence between equivalence classes of asymptotic reducibility parameters and asymptotically conserved (n−2)-forms in the context of Lagrangian gauge theories. The asymptotic reducibility parameters can be interpreted as asymptotic Killing vector fields of the background, with asymptotic behaviour determined by a new dynamical condition. A universal formula for asymptotically conserved (n−2)-forms in terms of the reducibility parameters is derived. Sufficient conditions for finiteness of the charges built out of the asymptotically conserved (n−2)-forms and for the existence of a Lie algebra g among equivalence classes of asymptotic reducibility parameters are given. The representation of g in terms of the charges may be centrally extended. An explicit and covariant formula for the central charges is constructed. They are shown to be 2-cocycles on the Lie algebra g. The general considerations and formulas are applied to electrodynamics, Yang–Mills theory and Einstein gravity.