44 research outputs found
Proposal for a Simple Model of Dynamical SUSY Breaking
We discuss supersymmetric gauge theory with a single matter field in
the representation. This theory has a moduli space of exactly
degenerate vacua. Classically it is the complex plane with an orbifold
singularity at the origin. There seem to be two possible candidates for the
quantum theory at the origin. In both the global chiral symmetry is unbroken.
The first is interacting quarks and gluons at a non-trivial infrared fixed
point -- a non-Abelian Coulomb phase. The second, which we consider more
likely, is a confining phase where the singularity is simply smoothed out. If
this second, more likely, possibility is realized, supersymmetry will
dynamically break when a tree level superpotential is added. This would be the
simplest known gauge theory which dynamically breaks supersymmetry.Comment: 6 page
D-term Inflation and Nonperturbative Kahler Potential of Dilaton
We study the -term inflation scenario with a nonperturbative K\"ahler
potential of the dilaton field. Although the FI term which leads an
inflationary expansion is given by the derivative of the K\"ahler potential
with respect to the dilaton in heterotic string models with anomalous U(1), the
too large magnitude is problematic for a viable -term inflation. In this
paper, we point out that the K\"ahler potential with a nonperturbative term can
reduce the magnitude of FI term to desired values while both the dilaton
stabilization and -term domination in the potential are realized by
nonperturbative superpotential.Comment: 13 pages, latex, 3 figure
ZZ brane amplitudes from matrix models
We study instanton contribution to the partition function of the one matrix
model in the k-th multicritical region, which corresponds to the (2,2k-1)
minimal model coupled to Liouville theory. The instantons in the one matrix
model are given by local extrema of the effective potential for a matrix
eigenvalue and identified with the ZZ branes in Liouville theory. We show that
the 2-instanton contribution in the partition function is universal as well as
the 1-instanton contribution and that the connected part of the 2-instanton
contribution reproduces the annulus amplitudes between the ZZ branes in
Liouville theory. Our result serves as another nontrivial check on the
correspondence between the instantons in the one matrix model and the ZZ branes
in Liouville theory, and also suggests that the expansion of the partition
function in terms of the instanton numbers are universal and gives
systematically ZZ brane amplitudes in Liouville theory.Comment: 29 pages, 4 figures; v2:how to scale x is generalized;
v3:introduction and the last section are revised, typos correcte
Universality of Nonperturbative Effects in c<1 Noncritical String Theory
Nonperturbative effects in c<1 noncritical string theory are studied using
the two-matrix model. Such effects are known to have the form fixed by the
string equations but the numerical coefficients have not been known so far.
Using the method proposed recently, we show that it is possible to determine
the coefficients for (p,q) string theory. We find that they are indeed finite
in the double scaling limit and universal in the sense that they do not depend
on the detailed structure of the potential of the two-matrix model.Comment: 17 page
Open Heterotic Strings
We classify potential cosmic strings according to the topological charge
measurable outside the string core. We conjecture that in string theory it is
this charge that governs the stability of long strings. This would imply that
the SO(32) heterotic string can have endpoints, but not the E_8 x E_8 heterotic
string. We give various arguments in support of this conclusion.Comment: 15 pages. v.2: typos, references correcte
D-branes at multicritical points
The moduli space of c=1 conformal field theories in two dimensions has a
multicritical point, where a circle theory is equivalent to an orbifold theory.
We analyse all the conformal branes in both descriptions of this theory, and
find convincing evidence that the full brane spectrum coincides. This shows
that the equivalence of the two descriptions at this multicritical point
extends to the boundary sector. We also perform the analogous analysis for one
of the multicritical points of the N=1 superconformal field theories at c=3/2.
Again the brane spectra are identical for both descriptions, however the
identification is more subtle.Comment: 32 pages, 2 figure
Non-Perturbative String Equations for Type 0A
Well-defined non-perturbative formulations of the physics of string theories,
sometimes with D-branes present, were identified over a decade ago, from a
careful study of double scaled matrix models. Following recent work which
recasts some of those old results in the context of type 0 string theory, a
study is made of a much larger family of models, which are proposed as type 0A
models of the entire superconformal minimal series coupled to gravity. This
gives many further examples of important physical phenomena, including
non-perturbative descriptions of transitions between D-branes and fluxes,
tachyon condensation, and holography. In particular, features of a large family
of non-perturbatively stable string equations are studied, and results are
extracted which pertain to type 0A string theory, with D-branes and fluxes, in
this large class of backgrounds. For the entire construction to work, large
parts of the spectrum of the supergravitationally dressed superconformal
minimal models and that of the gravitationally dressed bosonic conformal
minimal models must coincide, and it is shown how this happens. The example of
the super-dressed tricritical Ising model is studied in some detail.Comment: 29 pages LaTe
Tachyon Condensation, Open-Closed Duality, Resolvents, and Minimal Bosonic and Type 0 Strings
Type 0A string theory in the (2,4k) superconformal minimal model backgrounds
and the bosonic string in the (2,2k-1) conformal minimal models, while
perturbatively identical in some regimes, may be distinguished
non-perturbatively using double scaled matrix models. The resolvent of an
associated Schrodinger operator plays three very important interconnected
roles, which we explore perturbatively and non-perturbatively. On one hand, it
acts as a source for placing D-branes and fluxes into the background, while on
the other, it acts as a probe of the background, its first integral yielding
the effective force on a scaled eigenvalue. We study this probe at disc, torus
and annulus order in perturbation theory, in order to characterize the effects
of D-branes and fluxes on the matrix eigenvalues. On a third hand, the
integrated resolvent forms a representation of a twisted boson in an associated
conformal field theory. The entire content of the closed string theory can be
expressed in terms of Virasoro constraints on the partition function, which is
realized as wavefunction in a coherent state of the boson. Remarkably, the
D-brane or flux background is simply prepared by acting with a vertex operator
of the twisted boson. This generates a number of sharp examples of open-closed
duality, both old and new. We discuss whether the twisted boson conformal field
theory can usefully be thought of as another holographic dual of the
non-critical string theory.Comment: 37 pages, some figures, LaTe
Scattered Results in 2D String Theory
The nonperturbative tachyon scattering amplitude in 2D type 0A
string theory is computed. The probability that particles are produced is a
monotonically decreasing function of whenever is large enough that
statistical methods apply. The results are compared with expectations from
black hole thermodynamics.Comment: 22 pages, 5 figures, harvmac. v2: minor comments added, typos
correcte
Nonperturbative effects and nonperturbative definitions in matrix models and topological strings
We develop techniques to compute multi-instanton corrections to the 1/N
expansion in matrix models described by orthogonal polynomials. These
techniques are based on finding trans-series solutions, i.e. formal solutions
with exponentially small corrections, to the recursion relations characterizing
the free energy. We illustrate this method in the Hermitian, quartic matrix
model, and we provide a detailed description of the instanton corrections in
the Gross-Witten-Wadia (GWW) unitary matrix model. Moreover, we use Borel
resummation techniques and results from the theory of resurgent functions to
relate the formal multi-instanton series to the nonperturbative definition of
the matrix model. We study this relation in the case of the GWW model and its
double-scaling limit, providing in this way a nice illustration of various
mechanisms connecting the resummation of perturbative series to nonperturbative
results, like the cancellation of nonperturbative ambiguities. Finally, we
argue that trans-series solutions are also relevant in the context of
topological string theory. In particular, we point out that in topological
string models with both a matrix model and a large N gauge theory description,
the nonperturbative, holographic definition involves a sum over the
multi-instanton sectors of the matrix modelComment: 50 pages, 12 figures, comments and references added, small
correction