227 research outputs found
Supergravity dressing of beta-functions in N=1 and N=2 supersymmetric models
We discuss the dressing of one-loop sigma-model beta-functions by induced
supergravity, for both N=1 and N=2 supersymmetric theories. We obtain exact
results by a superconformal gauge argument, and verify them in the
semi-classical limit by explicit perturbative calculations in the light-cone
gauge. We find that for N=2 theories there is no dressing of the one-loop
beta-functions.Comment: 10 pages, latex, macros included, 2 figures in figures.u
Quantum Aspects of the Noncommutative Sine-Gordon Model
In this paper, we first use semi-classical methods to study quantum field
theoretical aspects of the integrable noncommutative sine-Gordon model proposed
in [hep-th/0406065]. In particular, we examine the fluctuations at quadratic
order around the static kink solution using the background field method. We
derive equations of motion for the fluctuations and argue that at O(theta^2)
the spectrum of fluctuations remains essentially the same as that of the
corresponding commutative theory. We compute the one-loop two-point functions
of the sine-Gordon field and the additional scalar field present in the model
and exhibit logarithmic divergences, only some of which lead to UV/IR mixing.
We briefly discuss the one-loop renormalization in Euclidean signature and
comment on the obstacles in determining the noncommutativity corrections to the
quantum mass of the kink.Comment: 1+14 pages, 8 eps figures, Added references, Version to appear in
JHE
Quantizing N=2 matter-supergravity systems
We consider supergravity coupled to Yang--Mills matter and
discuss the nature of one--loop divergences. Using superfields and
superspace methods, we describe the quantization of the system in the abelian
case.Comment: 18 pages, late
Effective K\"ahler Potentials
We compute the -loop effective K\"ahler potential in the most general
renormalizable supersymmetric quantum field theory.Comment: 11 pages, Late
Exact S-Matrices for Nonsimply-Laced Affine Toda Theories
We derive exact, factorized, purely elastic scattering matrices for affine
Toda theories based on the nonsimply-laced Lie algebras and superalgebras.Comment: 38 page
Perturbative Computation of Glueball Superpotentials
Using N=1 superspace techniques in four dimensions we show how to
perturbatively compute the superpotential generated for the glueball superfield
upon integrating out massive charged fields. The technique applies to arbitrary
gauge groups and representations. Moreover we show that for U(N) gauge theories
admitting a large N expansion the computation dramatically simplifies and we
prove the validity of the recently proposed recipe for computation of this
quantity in terms of planar diagrams of matrix integrals.Comment: 15 Pages, 2 Figure
Exact s-Matrices for the Nonsimply-Laced Affine Toda Theories
We derive the exact, factorized, purely elastic scattering matrices for the
family of nonsimply-laced affine Toda theories. The derivation
takes into account the distortion of the classical mass spectrum by radiative
correction, as well as modifications of the usual bootstrap assumptions since
for these theories anomalous threshold singularities lead to a displacement of
some single particle poles.Comment: 11 page
The Quantum Geometry of N=(2,2) Non-Linear Sigma-Models
We consider a general N=(2,2) non-linear sigma-model in (2,2) superspace.
Depending on the details of the complex structures involved, an off-shell
description can be given in terms of chiral, twisted chiral and semi-chiral
superfields. Using superspace techniques, we derive the conditions the
potential has to satisfy in order to be ultra-violet finite at one loop. We pay
particular attention to the effects due to the presence of semi-chiral
superfields. A complete description of N=(2,2) strings follows from this.Comment: 9 pages, Late
Nonholomorphic Corrections to the One-Loop N=2 Super Yang-Mills Action
In addition to the familiar contribution from a holomorphic function \FF,
the K\"ahler potential of the scalars in the nonabelian vector multiplet
receives contributions from a real function \HH. We determine the latter at
the one-loop level, taking into account both supersymmetric matter and gauge
loops. The function \HH characterizes the four-point coupling of the
vector-multiplet vectors for constant values of their scalar superpartners. We
discuss the consequences of our results.Comment: 11 pages, Latex, one Postscript figure. Corrections to equation (24):
1 missing term added and one pair of indices interchange
Infrared behavior of graviton-graviton scattering
The quantum effective theory of general relativity, independent of the
eventual full theory at high energy, expresses graviton-graviton scattering at
one loop order O(E^4) with only one parameter, Newton's constant. Dunbar and
Norridge have calculated the one loop amplitude using string based techniques.
We complete the calculation by showing that the 1/(d-4) divergence which
remains in their result comes from the infrared sector and that the cross
section is finite and model independent when the usual bremsstrahlung diagrams
are included.Comment: 12 pages, uses axodra
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