Searcharxiv⌕ Search

arXiv subjects

Marcus T. Grisaru

Publications and source records attributed to Marcus T. Grisaru.

12 recordsLinked to original sources
arXiv2006

Non(anti)commutative SYM theory: Renormalization in superspace

We present a systematic investigation of one-loop renormalizability for nonanticommutative N=1/2, U(N) SYM theory in superspace. We first discuss classical gauge invariance of the pure gauge theory and show that in contradistinction to the ordinary anticommutative case, different representations of supercovariant derivatives and field strengths do not lead to equivalent descriptions of the theory. Subsequently we develop background field methods which allow us to compute a manifestly covariant gauge effective action. One-loop evaluation of divergent contributions reveals that the theory simply obtained from the ordinary one by trading products for star products is not renormalizable. In the case of SYM with no matter we present a N=1/2 improved action which we show to be one-loop renormalizable and which is perfectly compatible with the algebraic structure of the star product. For this action we compute the beta functions. A brief discussion on the inclusion of chiral matter is also presented.

hep-th↗
arXiv2004

Some properties of the integrable noncommutative sine-Gordon system

In this paper we continue the program, initiated in Ref. hep-th/0112246, to investigate an integrable noncommutative version of the sine-Gordon model. We discuss the origin of the extra constraint which the field function has to satisfy in order to guarantee classical integrability. We show that the system of constraint plus dynamical equation of motion can be obtained by a suitable reduction of a noncommutative version of 4d self-dual Yang-Mills theory. The field equations can be derived from an action which is the sum of two WZNW actions with cosine potentials corresponding to a complexified noncommutative U(1) gauge group. A brief discussion of the relation with the bosonized noncommutative Thirring model is given. In spite of integrability we show that the S-matrix is acasual and particle production takes place.

hep-th↗
arXiv2003

Two-loop Renormalization for Nonanticommutative N=1/2 Supersymmetric WZ Model

We study systematically, through two loops, the divergence structure of the supersymmetric WZ model defined on the N=1/2 nonanticommutative superspace. By introducing a spurion field to represent the supersymmetry breaking term F^3 we are able to perform our calculations using conventional supergraph techniques. Divergent terms proportional to F, F^2 and F^3 are produced (the first two are to be expected on general grounds) but no higher-point divergences are found. By adding ab initio F and F^2 terms to the original lagrangian we render the model renormalizable. We determine the renormalization constants and beta functions through two loops, thus making it possible to study the renormalization group flow of the nonanticommutation parameter.

hep-th↗
arXiv2002

An integrable noncommutative version of the sine--Gordon system

Using the bicomplex approach we discuss a noncommutative system in two--dimensional Euclidean space. It is described by an equation of motion which reduces to the ordinary sine--Gordon equation when the noncommutation parameter is removed, plus a constraint equation which is nontrivial only in the noncommutative case. We show that the system has an infinite number of conserved currents and we give the general recursive relation for constructing them. For the particular cases of lower spin nontrivial currents we work out the explicit expressions and perform a direct check of their conservation. These currents reduce to the usual sine-Gordon currents in the commutative limit. We find classical ``localized'' solutions to first order in the noncommutativity parameter and describe the Backlund transformations for our system. Finally, we comment on the relation of our noncommutative system to the commutative sine-Gordon system.

hep-th↗
arXiv2000

Norcor vs the Abominable Gauge Completion

We use normal coordinate methods to obtain the expansion with respect to fermionic coordinates of the 11-dimensional supermembrane action in a supergravity background. Likewise, expansions for various branes in other dimensions can be obtained. These methods allow a systematic and unambiguous expansion of the vielbein to any order in the fermionic coordinates and avoid the complications encountered in the gauge completion approach.

hep-th↗
arXiv2000

Noncommutative Supersymmetric Gauge Anomaly

We extend the general method of hep-th/0009192 to compute the consistent gauge anomaly for noncommutative 4d SSYM coupled to chiral matter. The choice of the minimal homotopy path allows us to obtain a simple and compact result. We perform the reduction to components in the WZ gauge proving that our result contains, as lowest component, the bosonic chiral anomaly for noncommutative YM theories recently obtained in literature.

hep-th↗
arXiv2000

SUSY and Goliath

We investigate the `giant gravitons' of McGreevy, Susskind and Toumbas [hep-th/0003075]. We demonstrate that these are BPS configurations which preserve precisely the same supersymmetries as a `point-like' graviton. We also show that there exist `dual' giant gravitons consisting of spherical branes expanding into the AdS component of the spacetime. Finally, we discuss the realization of the stringy exclusion principle within this expanded framework.

hep-th↗
arXiv1997

Component Actions from Curved Superspace: Normal Coordinates and Ectoplasm

We give efficient superspace methods for deriving component actions for supergravity coupled to matter. One method uses normal coordinates to covariantly expand the superfield action, and can be applied straightforwardly to any superspace. The other interprets the component lagrangian as a differential form on a bosonic hypersurface in superspace, and gives a simple derivation for pertinent cases such as chiral superspace.

hep-th↗
arXiv1994

Prepotentials for (2,2) Supergravity

We present a complete solution of the constraints for two-dimensional, N=2 supergravity in N=2 superspace. We obtain explicit expressions for the covariant derivatives in terms of the vector superfield $H^m$ and, for the two versions of minimal (2,2) supergravity, a chiral or twisted chiral scalar superfield $ϕ$.

hep-th↗