2,753 research outputs found
Low-energy effective action in two-dimensional SQED: A two-loop analysis
We study two-loop quantum corrections to the low-energy effective actions in
N=(2,2) and N=(4,4) SQED in the Coulomb branch. In the latter model, the
low-energy effective action is described by a generalized Kahler potential
which depends on both chiral and twisted chiral superfields. We demonstrate
that this generalized Kahler potential is one-loop exact and corresponds to the
N=(4,4) sigma-model with torsion presented by Rocek, Schoutens and Sevrin. In
the N=(2,2) SQED, the effective Kahler potential is not protected against
higher-loop quantum corrections. The two-loop quantum corrections to this
potential and the corresponding sigma-model metric are explicitly found.Comment: 40 pages; v2: references added, typos correcte
On Low-Energy Effective Action of Noncommutative Hypermultiplet Model
We consider the noncommutative hypermultiplet model within harmonic
superspace approach. The 1-loop four-point contributions to the effective
action of selfinteracting q-hypermultiplet are computed. This model has two
coupling constants instead of a single one in commutative case. It is shown
that both these coupling constants are generated by 1-loop quantum corrections
in the model of q-hypermultiplet interacting with vector multiplet. The
holomorphic effective action of q-hypermultiplet in external gauge superfield
is calculated. For the fundamental representation there is no UV/IR-mixing and
the holomorphic potential is a star-product generalization of a standard
commutative one. For the adjoint representation of U(N) gauge group the leading
contributions to the holomorphic effective action are given by the terms
respecting for the UV/IR-mixing which are related to U(1) phase of U(N) group.Comment: 13 pages, 4 figures. v2: minor changes, refs adde
Superfield theories on and their localization
We consider the superfield formulation of supersymmetric gauge and matter
field theories on a three-dimensional sphere with rigid
supersymmetry, as well as with . The construction is based on a
supercoset containing as the bosonic subspace. We derive
an explicit form of supervielbein and covariant derivatives, and
use them to construct classical superfield actions for gauge and matter
supermultiplets in this superbackground. We then apply superfield methods for
computing one-loop partition functions of these theories and demonstrate how
the localization technique works directly in the superspace.Comment: 1+64 pages; v2: Section 4.2 and a reference are adde
Two-loop low-energy effective action in Abelian supersymmetric Chern-Simons matter models
We compute two-loop low-energy effective actions in Abelian Chern-Simons
matter models with N=2 and N=3 supersymmetry up to four-derivative order.
Calculations are performed with a slowly-varying gauge superfield background.
Though the gauge superfield propagator depends on the gauge fixing parameter,
it is shown that the obtained results are independent of this parameter. In the
massless case the considered models are superconformal. We demonstrate that the
superconformal symmetry strongly restricts the form of two-loop quantum
corrections to the effective actions such that the obtained terms have simpler
structure than the analogous ones in the effective action of three-dimensional
supersymmetric electrodynamics (SQED) with vanishing topological mass.Comment: 1+30 pages; v2: references added, misprints corrected; v3: minor
changes, published versio
On Holomorphic Effective Actions of Hypermultiplets Coupled to External Gauge Superfields
We study the structure of holomorphic effective action for hypermultiplet
models interacting with background super Yang-Mills fields. A general form of
holomorphic effective action is found for hypermultiplet belonging to arbitrary
representation of any semisimple compact Lie group spontaneously broken to its
maximal abelian subgroup. The applications of obtained results to
hypermultiplets in fundamental and adjoint representations of the SU(n), SO(n),
Sp(n) groups are considered.Comment: 8 pages, no figure
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