156 research outputs found
Spectral networks and higher web-like structures
We derive traffic rule for spectral networks for A_2 theory for Riemann
surface with punctures and use it to study in details the moduli space M of
flat GL(3,C) connections on P^1 with 3 full punctures. We apply the simplified
traffic rule to find the global description of M as the fibration with
symplectic fibers and to study the space of line defects in 4d theory
corresponding to the conformal point in the base of M. We define higher
web-like structures, not previously discussed in the literature. They give rise
to line defects independent of the defects corresponding to the traces of
holonomies.Comment: 22 pages, 14 figure
Fivebrane Lagrangian with Loop Corrections in Field-Theory Limit
Equations of motion and the lagrangian are derived explicitely for Dual D=10,
N=1 Supergravity considered as a field theory limit of a Fivebrane. It is used
the mass-shell solution of Heterotic String Bianchi Identites obtained in the
2-dimensional -model two-loop approximation and in the tree-level
Heterotic String approximation. As a result the Dual Supergravity lagrangian is
derived in the one-loop Five-Brane approximation and in the lowest
6-dimensional -model approximaton.Comment: 21 page
Gauge Mediation in F-Theory GUT Models
We study a simple framework for gauge-mediated supersymmetry-breaking in
local GUT models based on F-theory 7-branes and demonstrate that a mechanism
for solving both the \mu and \mu/B_{\mu} problems emerges in a natural way. In
particular, a straightforward coupling of the messengers to the Higgs sector
leads to a geometry which not only provides us with an approximate U(1)_{PQ}
symmetry that forbids the generation of \mu at the GUT scale, it also forces
the SUSY-breaking spurion field to carry a nontrivial PQ charge. This connects
the breaking of SUSY to the generation of \mu so that the same scale enters
both. Moreover, the messenger sector naturally realizes the D3-instanton
triggered Polonyi model of arXiv:0808.1286 so this scale is exponentially
suppressed relative to M_{GUT}. The effective action at low scales is in fact
precisely of the form of the "sweet spot supersymmetry" scenario studied by Ibe
and Kitano in arXiv:0705.3686.Comment: 34 pages, 4 figures; v4 revisions to section
Global Gluing and G-flux
Local models that capture the 7-brane physics of F-theory compactifications
for supersymmetric GUTs are conveniently described in terms of an E_8 gauge
theory in the presence of a Higgs bundle. Though the Higgs bundle data is
usually determined by the local geometry and G-flux, additional gluing data
must be specified whenever the Higgs bundle spectral cover is not smooth. In
this paper, we argue that this additional information is determined by data of
the M-theory 3-form that is not necessarily captured by the cohomology class of
the G-flux. More specifically, we show that when the 3-form is specified in
terms of a line bundle on a spectral divisor, which is a global extension of
the Higgs bundle spectral cover, the gluing data of the local model is uniquely
determined in a way that ensures agreement with Heterotic results whenever a
Heterotic dual exists.Comment: 22 page
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