360 research outputs found
A natural renormalizable model of metastable SUSY breaking
We propose a model of metastable dynamical supersymmetry breaking in which
all scales are generated dynamically. Our construction is a simple variant of
the Intriligator-Seiberg-Shih model, with quark masses induced by
renormalizable couplings to an auxiliary supersymmetric QCD sector. Since all
scales arise from dimensional transmutation, the model has no fundamental
dimensionful parameters. It also does not rely on higher-dimensional operators.Comment: 9 pages; v2: typos correcte
Simultaneous identification of damping coefficient and initial value for PDEs from boundary measurement
Four graviton scattering amplitude from supersymmetric orbifold sigma model
In the IR limit the Matrix string theory is expected to be described by the
supersymmetric orbifold sigma model. Recently Dijkgraaf, Verlinde
and Verlinde proposed a vertex that may describe the type IIA string
interaction. In this paper using this interaction vertex we derive the four
graviton scattering amplitude from the orbifold model in the large limit.Comment: latex, 35 pages, misprints are corrected, the final version to appear
in Nucl.Phys.
Space as a low-temperature regime of graphs
I define a statistical model of graphs in which 2-dimensional spaces arise at
low temperature. The configurations are given by graphs with a fixed number of
edges and the Hamiltonian is a simple, local function of the graphs.
Simulations show that there is a transition between a low-temperature regime in
which the graphs form triangulations of 2-dimensional surfaces and a
high-temperature regime, where the surfaces disappear. I use data for the
specific heat and other observables to discuss whether this is a phase
transition. The surface states are analyzed with regard to topology and
defects.Comment: 22 pages, 12 figures; v3: published version; J.Stat.Phys. 201
Meta-Stable Supersymmetry Breaking in a Cooling Universe
We look at the recently proposed idea that susy breaking can be accomplished
in a meta-stable vacuum. In the context of one of the simplest models (the
Seiberg-dual of super-QCD), we address the following question: if we look at
this theory as it cools from high temperature, is it at all possible that we
can end up in a susy-breaking meta-stable vacuum? To get an idea about the
answer, we look at the free energy of the system at high temperature. We
conclude that the phase-structure of the free-energy as the temperature drops,
is indeed such that there is a second order phase transition in the direction
of the non-susy vacuum at a finite . On the other hand, the potential
barrier in the direction of the susy vacuum is there all the way till .Comment: writing full author name
Particle creation in a tunneling universe
An expanding closed universe filled with radiation can either recollapse or
tunnel to the regime of unbounded expansion, if the cosmological constant is
nonzero. We re-examine the question of particle creation during tunneling, with
the purpose of resolving a long-standing controversy. Using a perturbative
superspace model with a conformally coupled massless scalar field, which is
known to give no particle production, we explicitly show that the breakdown of
the semiclassical approximation and the ``catastrophic particle production''
claimed earlier in the literature are due to an inappropriate choice of the
initial quantum state prior to the tunneling.Comment: 21 pages, 3 embedded figures, RevTeX
Instanton test of non-supersymmetric deformations of the AdS_5 x S^5
We consider instanton effects in a non-supersymmetric gauge theory obtained
by marginal deformations of the N=4 SYM. This gauge theory is expected to be
dual to type IIB string theory on the AdS_5 times deformed-S^5 background. From
an instanton calculation in the deformed gauge theory we extract the prediction
for the dilaton-axion field \tau in dual string theory. In the limit of small
deformations where the supergravity regime is valid, our instanton result
reproduces the expression for \tau of the supergravity solution found by
Frolov.Comment: 15 page
Closed-String Tachyons and the Hagedorn Transition in AdS Space
We discuss some aspects of the behaviour of a string gas at the Hagedorn
temperature from a Euclidean point of view. Using AdS space as an infrared
regulator, the Hagedorn tachyon can be effectively quasi-localized and its
dynamics controled by a finite energetic balance. We propose that the off-shell
RG flow matches to an Euclidean AdS black hole geometry in a generalization of
the string/black-hole correspondence principle. The final stage of the RG flow
can be interpreted semiclassically as the growth of a cool black hole in a
hotter radiation bath. The end-point of the condensation is the large Euclidean
AdS black hole, and the part of spacetime behind the horizon has been removed.
In the flat-space limit, holography is manifest by the system creating its own
transverse screen at infinity. This leads to an argument, based on the
energetics of the system, explaining why the non-supersymmetric type 0A string
theory decays into the supersymmetric type IIB vacuum. We also suggest a notion
of `boundary entropy', the value of which decreases along the line of flow.Comment: 24 pages, Harvmac. 2 Figures. Typos corrected and reference adde
The Hamiltonian limit of (3+1)D SU(3) lattice gauge theory on anisotropic lattices
The extreme anisotropic limit of Euclidean SU(3) lattice gauge theory is
examined to extract the Hamiltonian limit, using standard path integral Monte
Carlo (PIMC) methods. We examine the mean plaquette and string tension and
compare them to results obtained within the Hamiltonian framework of Kogut and
Susskind. The results are a significant improvement upon previous Hamiltonian
estimates, despite the extrapolation procedure necessary to extract
observables. We conclude that the PIMC method is a reliable method of obtaining
results for the Hamiltonian version of the theory. Our results also clearly
demonstrate the universality between the Hamiltonian and Euclidean formulations
of lattice gauge theory. It is particularly important to take into account the
renormalization of both the anisotropy, and the Euclidean coupling ,
in obtaining these results.Comment: 10 pages, 11 figure
The staggered domain wall fermion method
A different lattice fermion method is introduced. Staggered domain wall
fermions are defined in 2n+1 dimensions and describe 2^n flavors of light
lattice fermions with exact U(1) x U(1) chiral symmetry in 2n dimensions. As
the size of the extra dimension becomes large, 2^n chiral flavors with the same
chiral charge are expected to be localized on each boundary and the full
SU(2^n) x SU(2^n) flavor chiral symmetry is expected to be recovered. SDWF give
a different perspective into the inherent flavor mixing of lattice fermions and
by design present an advantage for numerical simulations of lattice QCD
thermodynamics. The chiral and topological index properties of the SDWF Dirac
operator are investigated. And, there is a surprise ending...Comment: revtex4, 7 figures, minor revisions, 2 references adde
- …