226 research outputs found

    Supergravity dressing of beta-functions in N=1 and N=2 supersymmetric models

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    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

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    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

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    We consider N=2N=2 supergravity coupled to N=2N=2 Yang--Mills matter and discuss the nature of one--loop divergences. Using N=1N=1 superfields and superspace methods, we describe the quantization of the system in the abelian case.Comment: 18 pages, late

    Effective K\"ahler Potentials

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    We compute the 11-loop effective K\"ahler potential in the most general renormalizable N=1N=1 d=4d=4 supersymmetric quantum field theory.Comment: 11 pages, Late

    Exact S-Matrices for Nonsimply-Laced Affine Toda Theories

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    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

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    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 a2n‚ąí1(2)a_{2n-1}^{(2)}

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    We derive the exact, factorized, purely elastic scattering matrices for the a2n‚ąí1(2)a_{2n-1}^{(2)} 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

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    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

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    In addition to the familiar contribution from a holomorphic function \FF, the K\"ahler potential of the scalars in the nonabelian N=2N=2 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 N=2N=2 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

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    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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