59,970 research outputs found
From Perturbation Theory to Confinement: How the String Tension is built up
We study the spatial volume dependence of electric flux energies for SU(2)
Yang-Mills fields on the torus with twisted boundary conditions. The results
approach smoothly the rotational invariant Confinement regime. The would-be
string tension is very close to the infinite volume result already for volumes
of . We speculate on the consequences of our result for
the Confinement mechanism.Comment: 6p, ps-file (uuencoded). Contribution to Lattice'93 Conference
(Dallas, 1993). Preprint INLO-PUB 18/93, FTUAM-93/4
Video Prioritization for Unequal Error Protection
We analyze the effect of packet losses in video sequences and propose a lightweight Unequal Error Protection strategy which, by choosing which packet is discarded, reduces strongly the Mean Square Error of the received sequenc
Topology by improved cooling: susceptibility and size distributions
We use a cooling algorithm based on an improved action with scale invariant
instanton solutions, which needs no monitoring or calibration and has a
inherent cut off for dislocations. We present results for SU(2) Yang-Mills
theory where the method provides good susceptibility data and physical size
distributions of instantons.Comment: 3 pages, 4 figures. Talk presented at LATTICE96(topology
Chern-Simons theory encoded on a spin chain
We construct a 1d spin chain Hamiltonian with generic interactions and prove
that the thermal correlation functions of the model admit an explicit random
matrix representation. As an application of the result, we show how the
observables of Chern-Simons theory on can be reproduced with the
thermal correlation functions of the 1d spin chain, which is of the XX type,
with a suitable choice of exponentially decaying interactions between
infinitely many neighbours. We show that for this model, the correlation
functions of the spin chain at a finite temperature give the
Chern-Simons partition function, quantum dimensions and the full topological
-matrix.Comment: v2, 11 pages. Expanded, more detailed version. Misprints correcte
Memory effects can make the transmission capability of a communication channel uncomputable
Most communication channels are subjected to noise. One of the goals of
Information Theory is to add redundancy in the transmission of information so
that the information is transmitted reliably and the amount of information
transmitted through the channel is as large as possible. The maximum rate at
which reliable transmission is possible is called the capacity. If the channel
does not keep memory of its past, the capacity is given by a simple
optimization problem and can be efficiently computed. The situation of channels
with memory is less clear. Here we show that for channels with memory the
capacity cannot be computed to within precision 1/5. Our result holds even if
we consider one of the simplest families of such channels -information-stable
finite state machine channels-, restrict the input and output of the channel to
4 and 1 bit respectively and allow 6 bits of memory.Comment: Improved presentation and clarified claim
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