16,774 research outputs found
Dynamical Supersymmetry Breaking in Intersecting Brane Models
In this paper we study dynamical supersymmetry breaking in absence of gravity
with the matter content of the minimal supersymmetric standard model. The
hidden sector of the theory is a strongly coupled gauge theory, realized in
terms of microscopic variables which condensate to form mesons. The
supersymmetry breaking scalar potential combines F, D terms with instanton
generated interactions in the Higgs-mesons sector. We show that for a large
region in parameter space the vacuum breaks in addition to supersymmetry also
electroweak gauge symmetry. We furthermore present local D-brane configurations
that realize these supersymmetry breaking patterns.Comment: 30 pages, 4 figures, pdflate
Partition Functions of Pure Spinors
We compute partition functions describing multiplicities and charges of
massless and first massive string states of pure-spinor superstrings in
3,4,6,10 dimensions. At the massless level we find a spin-one gauge multiplet
of minimal supersymmetry in d dimensions. At the first massive string level we
find a massive spin-two multiplet. The result is confirmed by a direct analysis
of the BRST cohomology at ghost number one. The central charges of the pure
spinor systems are derived in a manifestly SO(d) covariant way confirming that
the resulting string theories are critical. A critical string model with
N=(2,0) supersymmetry in d=2 is also described.Comment: LaTex, 30 p
A note on supersymmetric D-brane dynamics
We study the spin dependence of D-brane dynamics in the Green-Schwarz
formalism of boundary states. In particular we show how to interpret insertion
of supercharges on the boundary state as sources of non-universal spin effects
in D-brane potentials. In this way we find for a generic (D)p-brane, potentials
going like corresponding to interactions between the
different components of the D-brane supermultiplet. From the eleven dimensional
point of view, these potentials arise from the exchange of field strengths
corresponding to the graviton and the three form, coupled non-minimally to the
branes. We show how an annulus computation truncated to its massless
contribution is enough to reproduce these next-to-leading effects, meaning in
particular that the one-loop (M)atrix theory effective action should encode all
the spin dependence of low-energy supergravity interactions.Comment: LaTex file, 12 pages, no figures, some corrections in last section
and references added; version to appear in Physics Letters
S-duality and the prepotential in N=2* theories (I): the ADE algebras
The prepotential of N=2* supersymmetric theories with unitary gauge groups in
an Omega-background satisfies a modular anomaly equation that can be
recursively solved order by order in an expansion for small mass. By requiring
that S-duality acts on the prepotential as a Fourier transform we generalise
this result to N=2* theories with gauge algebras of the D and E type and show
that their prepotentials can be written in terms of quasi-modular forms of
SL(2,Z). The results are checked against microscopic multi-instanton calculus
based on localization for the A and D series and reproduce the known
1-instanton prepotential of the pure N=2 theories for any gauge group of ADE
type. Our results can also be used to obtain the multi-instanton terms in the
exceptional theories for which the microscopic instanton calculus and the ADHM
construction are not available.Comment: 33 pages, LaTeX2e, added references, version to be published in JHE
On the perturbative corrections around D-string instantons
We study -threshold corrections in an eight dimensional S-dual
pair of string theories, as a prototype of dual string vacua with sixteen
supercharges. We show that the orbifold CFT description of D-string instantons
gives rise to a perturbative expansion similar to the one appearing on the
fundamental string side. By an explicit calculation, using the Nambu-Goto
action in the static gauge, we show that the first subleading term agrees
precisely on the two sides. We then give a general argument to show that the
agreement extends to all orders.Comment: 12 page
AdS/CFT correspondence and D1/D5 systems in theories with 16 supercharges
We discuss spectra of supergravities, arising in the near horizon
geometry of D1/D5 systems in orbifolds/orientifolds of type IIB theory with 16
supercharges. These include models studied in a recent paper (hep-th/0012118),
where the group action involves also a shift along a transversal circle, as
well as IIB/, which is dual to IIB on . After appropriate
assignements of the orbifold group eigenvalues and degrees to the supergravity
single particle spectrum, we compute the supergravity elliptic genus and find
agreement, in the expected regime of validity, with the elliptic genus obtained
using U-duality map from (4,4) CFTs of U-dual backgrounds. Since this U-duality
involves the exchange of KK momentum and D1 charge , it allows us to
test the (4,4) CFTs in the and regimes by two different
supergravity duals.Comment: 28 pages, no figure
Real sector of the nonminimally coupled scalar field to self-dual gravity
A scalar field nonminimally coupled to gravity is studied in the canonical
framework, using self-dual variables. The corresponding constraints are first
class and polynomial. To identify the real sector of the theory, reality
conditions are implemented as second class constraints, leading to three real
configurational degrees of freedom per space point. Nevertheless, this
realization makes non-polynomial some of the constraints. The original complex
symplectic structure reduces to the expected real one, by using the appropriate
Dirac brackets. For the sake of preserving the simplicity of the constraints,
an alternative method preventing the use of Dirac brackets, is discussed. It
consists of converting all second class constraints into first class by adding
extra variables. This strategy is implemented for the pure gravity case.Comment: Latex file, 22 pages, no figure
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