5,332 research outputs found
A matrix model for strings beyond the c=1 barrier: the spin-s Heisenberg model on random surfaces
We consider a spin-s Heisenberg model coupled to two-dimensional quantum
gravity. We quantize the model using the Feynman path integral, summing over
all possible two-dimensional geometries and spin configurations. We regularize
this path integral by starting with the R-matrices defining the spin-s
Heisenberg model on a regular 2d Manhattan lattice. 2d quantum gravity is
included by defining the R-matrices on random Manhattan lattices and summing
over these, in the same way as one sums over 2d geometries using random
triangulations in non-critical string theory. We formulate a random matrix
model where the partition function reproduces the annealed average of the
spin-s Heisenberg model over all random Manhattan lattices. A technique is
presented which reduces the random matrix integration in partition function to
an integration over their eigenvalues.Comment: 18 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1304.690
Exploring singlet deflection of gauge mediation
We embed the Next-to Minimal Supersymmetric Standard Model into gauge
mediation of supersymmetry breaking and study the phenomenology of scenarios
where the gauge-mediation contributions to soft parameters are deflected by
superpotential interactions of the gauge singlet with the messenger fields and
the Higgs doublets. This kind of models provide a satisfactory solution to the
mu-b_mu problem of gauge mediation, compatible with the adequate pattern of
electroweak symmetry breaking and a realistic spectrum with supersymmetric
partners at the TeV scale without requiring a significant fine tuning.Comment: Latex 18 pages, 4 eps figures. Minor corrections, version published
in Phys. Rev.
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