1,077 research outputs found
Renormalizability of N=1/2 Wess-Zumino model in superspace
In this letter we use the spurion field approach adopted in hep-th/0307099 in
order to show that by adding F and F^2 terms to the original lagrangian, the
N=1/2 Wess-Zumino model is renormalizable to all orders in perturbation theory.
We reformulate in superspace language the proof given in the recent work
hep-th/0307165 in terms of component fields.Comment: 8 pages, minor change
One-loop divergences in the two-dimensional non-anticommutative supersymmetric sigma-model
We discuss the structure of the non-anticommutative N=2 non-linear
sigma-model in two dimensions, constructing differential operators which
implement the deformed supersymmetry generators and using them to reproduce the
classical action. We then compute the one-loop quantum corrections and express
them in a more compact form using the differential operators.Comment: 20pp, 8 figures, uses LaTeX. Title expanded to clarify conten
N=1/2 gauge theory and its instanton moduli space from open strings in R-R background
We derive the four dimensional N=1/2 super Yang-Mills theory from tree-level
computations in RNS open string theory with insertions of closed string
Ramond-Ramond vertices. We also study instanton configurations in this gauge
theory and their ADHM moduli space, using systems of D3 and D(-1) branes in a
R-R background.Comment: 29 pages, 6 figures, JHEP class (included
On Instantons and Zero Modes of N=1/2 SYM Theory
We study zero modes of N=1/2 supersymmetric Yang-Mills action in the
background of instantons. In this background, because of a quartic antichiral
fermionic term in the action, the fermionic solutions of the equations of
motion are not in general zero modes of the action. Hence, when there are
fermionic solutions, the action is no longer minimized by instantons. By
deforming the instanton equation in the presence of fermions, we write down the
zero mode equations. The solutions satisfy the equations of motion, and
saturate the BPS bound. The deformed instanton equations imply that the finite
action solutions have U(1) connections which are not flat anymore.Comment: 9 pages, latex file, added references, minor change
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.Comment: Latex file, 59 pages, 10 figures, One reference adde
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.Comment: 36 pages, 25 figures, Latex fil
N=1/2 Super Yang-Mills Theory on Euclidean AdS2xS2
We study D-branes in the background of Euclidean AdS2xS2 with a graviphoton
field turned on. As the background is not Ricci flat, the graviphoton field
must have both self-dual and antiself-dual parts. This, in general, will break
all the supersymmetries on the brane. However, we show that there exists a
limit for which one can restore half of the supersymmetries. Further, we show
that in this limit, the N=1/2 SYM Lagrangian on flat space can be lifted on to
the Euclidean AdS2xS2 preserving the same amount of supersymmetries as in the
flat case. We observe that without the C-dependent terms present in the action
this lift is not possible.Comment: 12 pages, latex file; v2: minor corrections, references adde
From lightcone actions to maximally supersymmetric amplitudes
In this article actions for N=4 SYM and N=8 supergravity are formulated in
terms of a chiral superfield, which contains only the physical degrees of
freedom of either theory. In these new actions, which originate from the
lightcone superspace, the supergravity cubic vertex is the square of the gauge
theory one (omitting the color structures). Amplitude calculations using the
corresponding Feynman supergraph rules are tedious, but can be simplified by
choosing a preferred superframe. Recursive calculations of all MHV amplitudes
in N=4 SYM and the four-point N=8 supergravity amplitude are shown to agree
with the known results and connections to the BCFW recursion relations are
pointed out. Finally, the new path integrals are discussed in the context of
the double-copy property relating N=4 SYM theory to N=8 supergravity.Comment: 29 pages, 2 figures, v2: title modified, published versio
Gauge Theory on Noncommutative Supersphere from Supermatrix Model
We construct a supermatrix model which has a classical solution representing
the noncommutative (fuzzy) two-supersphere. Expanding supermatrices around the
classical background, we obtain a gauge theory on a noncommutative superspace
on sphere. This theory has supersymmetry and gauge
symmetry. We also discuss a commutative limit of the model keeping radius of
the supersphere fixed.Comment: 16 pages, Latex, typos corrected, references adde
- …