57 research outputs found
Classical Solutions of the TEK Model and Noncommutative Instantons in Two Dimensions
The twisted Eguchi-Kawai (TEK) model provides a non-perturbative definition
of noncommutative Yang-Mills theory: the continuum limit is approached at large
by performing suitable double scaling limits, in which non-planar
contributions are no longer suppressed. We consider here the two-dimensional
case, trying to recover within this framework the exact results recently
obtained by means of Morita equivalence. We present a rather explicit
construction of classical gauge theories on noncommutative toroidal lattice for
general topological charges. After discussing the limiting procedures to
recover the theory on the noncommutative torus and on the noncommutative plane,
we focus our attention on the classical solutions of the related TEK models. We
solve the equations of motion and we find the configurations having finite
action in the relevant double scaling limits. They can be explicitly described
in terms of twist-eaters and they exactly correspond to the instanton solutions
that are seen to dominate the partition function on the noncommutative torus.
Fluxons on the noncommutative plane are recovered as well. We also discuss how
the highly non-trivial structure of the exact partition function can emerge
from a direct matrix model computation. The quantum consistency of the TEK
formulation is eventually checked by computing Wilson loops in a particular
limit.Comment: 41 pages, JHEP3. Minor corrections, references adde
Fermion Electric Dipole Moments in Supersymmetric Models with R-parity Violation
We analyze the electron and neutron electric dipole moments induced by
R-parity violating interactions in supersymmetric models. It is pointed out
that dominant contributions can come from one-loop diagrams involving both the
bilinear and trilinear R-parity odd couplings, leading to somewhat severe
constraints on the products of those couplings.Comment: Revtex, 19pp, four figures in axodraw.st
Space-Time Foam Effects on Particle Interactions and the GZK Cutoff
Modelling space-time foam using a non-critical Liouville-string model for the
quantum fluctuations of D branes with recoil, we discuss the issues of momentum
and energy conservation in particle propagation and interactions. We argue that
momentum should be conserved exactly during propagation and on the average
during interactions, but that energy is conserved only on the average during
propagation and is in general not conserved during particle interactions,
because of changes in the background metric. We discuss the possible
modification of the GZK cutoff on high-energy cosmic rays, in the light of this
energy non-conservation as well as the possible modification of the usual
relativistic momentum-energy relation.Comment: 20 pages LaTe
Histamine releasing and anti-inflammatory activities of MCD-peptide and its modified forms
Modification of spacecraft charging and the near-plasma environment caused by the interaction of an artificial electron beam with the earth's upper atmosphere
Attenuation of cocaine self-administration by chronic oral phendimetrazine in rhesus monkeys
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