13,147 research outputs found
Lagrangians with electric and magnetic charges of N=2 supersymmetric gauge theories
General Lagrangians are constructed for N=2 supersymmetric gauge theories in
four space-time dimensions involving gauge groups with (non-abelian) electric
and magnetic charges. The charges induce a scalar potential, which, when the
charges are regarded as spurionic quantities, is invariant under
electric/magnetic duality. The resulting theories are especially relevant for
supergravity, but details of the extension to local supersymmetry will be
discussed elsewhere. The results include the coupling to hypermultiplets.
Without the latter, it is demonstrated how an off-shell representation can be
constructed based on vector and tensor supermultiplets.Comment: 34 pages, LaTe
The Vector-Tensor Supermultiplet with Gauged Central Charge
The vector-tensor multiplet is coupled off-shell to an N=2 vector multiplet
such that its central charge transformations are realized locally. A gauged
central charge is a necessary prerequisite for a coupling to supergravity and
the strategy underlying our construction uses the potential for such a coupling
as a guiding principle. The results for the action and transformation rules
take a nonlinear form and necessarily include a Chern-Simons term. After a
duality transformation the action is encoded in a homogeneous holomorphic
function consistent with special geometry.Comment: 8 pages, LATE
E_{7(7)} symmetry and dual gauge algebra of M-theory on a twisted seven-torus
We consider M-theory compactified on a twisted 7-torus with fluxes when all
the seven antisymmetric tensor fields in four dimensions have been dualized
into scalars and thus the E_{7(7)} symmetry is recovered. We find that the
Scherk--Schwarz and flux gaugings define a ``dual'' gauge algebra, subalgbra of
E_{7(7)}, where some of the generators are associated with vector fields which
are dual to part of the original vector fields (deriving from the 3-form). In
particular they are dual to those vector fields which have been ``eaten'' by
the antisymmetric tensors in the original theory by the (anti-)Higgs mechanism.
The dual gauge algebra coincides with the original gauge structure when the
quotient with respect to these dual (broken) gauge generators is taken. The
particular example of the S-S twist corresponding to a ``flat group'' is
considered.Comment: 12 pages, LaTeX file, typos corrected, references added, some
discussions extende
The N=2 Super Yang-Mills Low-Energy Effective Action at Two Loops
We have carried out a two loop computation of the low-energy effective action
for the four-dimensional N=2 supersymmetric Yang-Mills system coupled to
hypermultiplets, with the chiral superfields of the vector multiplet lying in
an abelian subalgebra. We have found a complete cancellation at the level of
the integrands of Feynman amplitudes, and therefore the two loop contribution
to the action, effective or Wilson, is identically zero.Comment: 8 pages, Latex, 2 .eps figure
Einstein-Cartan theory as a theory of defects in space-time
The Einstein-Cartan theory of gravitation and the classical theory of defects
in an elastic medium are presented and compared. The former is an extension of
general relativity and refers to four-dimensional space-time, while we
introduce the latter as a description of the equilibrium state of a
three-dimensional continuum. Despite these important differences, an analogy is
built on their common geometrical foundations, and it is shown that a
space-time with curvature and torsion can be considered as a state of a
four-dimensional continuum containing defects. This formal analogy is useful
for illustrating the geometrical concept of torsion by applying it to concrete
physical problems. Moreover, the presentation of these theories using a common
geometrical basis allows a deeper understanding of their foundations.Comment: 18 pages, 7 EPS figures, RevTeX4, to appear in the American Journal
of Physics, revised version with typos correcte
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