448 research outputs found
Spontaneous R-symmetry Breaking with Multiple Pseudomoduli
We examine generalized O'Raifeartaigh models that feature multiple tree-level
flat directions and only contain fields with R-charges 0 or 2. We show that
spontaneous R-breaking at up to one-loop order is impossible in such theories.
Specifically, we prove that the R-symmetric origin of field space is always a
local minimum of the one-loop Coleman-Weinberg potential, generalizing an
earlier result for the case of a single flat direction. This result has
consequences for phenomenology and helps elucidate the behavior of various
models of dynamical SUSY breaking
Dynamical SUSY and R-symmetry breaking in SQCD with massive and massless flavors
We show that supersymmetry and R-symmetry can be dynamically broken in a
long-lived metastable vacuum of SQCD with massive and massless flavors. The
vacuum results from a competition of a (leading) two-loop effect and small
"Planck" suppressed higher-dimension operators. This mechanism provides a
particularly simple realization of dynamical SUSY and R-symmetry breaking, and
as such it is a good starting point for building phenomenologically viable
models of gauge mediation. We take a preliminary step in this direction by
constructing a complete model of minimal gauge mediation. Here we find that the
parameters of the model are surprisingly constrained by the hidden sector.
Similar mechanisms for creating long-lived states operate in a large class of
models.Comment: 25 pages. v2: added references, minor correctio
Goal-conflict detection based on temporal satisfiability checking
Goal-oriented requirements engineering approaches propose capturing how a system should behave through the speci ca- tion of high-level goals, from which requirements can then be systematically derived. Goals may however admit subtle situations that make them diverge, i.e., not be satis able as a whole under speci c circumstances feasible within the domain, called boundary conditions . While previous work al- lows one to identify boundary conditions for con icting goals written in LTL, it does so through a pattern-based approach, that supports a limited set of patterns, and only produces pre-determined formulations of boundary conditions. We present a novel automated approach to compute bound- ary conditions for general classes of con icting goals expressed in LTL, using a tableaux-based LTL satis ability procedure. A tableau for an LTL formula is a nite representation of all its satisfying models, which we process to produce boundary conditions that violate the formula, indicating divergence situations. We show that our technique can automatically produce boundary conditions that are more general than those obtainable through existing previous pattern-based approaches, and can also generate boundary conditions for goals that are not captured by these patterns
Comments on worldsheet theories dual to free large N gauge theories
We continue to investigate properties of the worldsheet conformal field
theories (CFTs) which are conjectured to be dual to free large N gauge
theories, using the mapping of Feynman diagrams to the worldsheet suggested in
hep-th/0504229. The modular invariance of these CFTs is shown to be built into
the formalism. We show that correlation functions in these CFTs which are
localized on subspaces of the moduli space may be interpreted as delta-function
distributions, and that this can be consistent with a local worldsheet
description given some constraints on the operator product expansion
coefficients. We illustrate these features by a detailed analysis of a specific
four-point function diagram. To reliably compute this correlator we use a novel
perturbation scheme which involves an expansion in the large dimension of some
operators.Comment: 43 pages, 16 figures, JHEP format. v2: added reference
The random-bond Ising model in 2.01 and 3 dimensions
We consider the Ising model between 2 and 4 dimensions perturbed by quenched disorder in the strength of the interaction between nearby spins. In the interval 2 < d < 4 this disorder is a relevant perturbation that drives the system to a new fixed point of the renormalization group. At d = 2 such disorder is marginally irrelevant and can be studied using conformal perturbation theory. Combining conformal perturbation theory with recent results from the conformal bootstrap we compute some scaling exponents in an expansion around d = 2. If one trusts these computations also in d = 3, one finds results consistent with experimental data and Monte Carlo simulations. In addition, we perform a direct uncontrolled computation in d = 3 using new results for low-lying operator dimensions and OPE coefficients in the 3d Ising model. We compare these new methods with previous studies. Finally, we comment about the O(2) model in d = 3, where we predict a large logarithmic correction to the infrared scaling of disorder
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