4,027 research outputs found
Method for leakage testing of tanks Patent
Development of apparatus and method for testing leakage of large tank
The Renormalization Group According to Balaban - I. Small fields
This is an expository account of Balaban's approach to the renormalization
group. The method is illustrated with a treatment of the the ultraviolet
problem for the scalar phi^4 model on a toroidal lattice in dimension d=3. This
yields another proof of the stability bound. In this first paper we analyze the
small field contribution to the partition function.Comment: 52 pages. Some corrections, additions, reorganizatio
Super-Instantons in Gauge Theories and Troubles with Perturbation Theory
In gauge theories with continuous groups there exist classical solutions
whose energy vanishes in the thermodynamic limit (in any dimension). The
existence of these super-instantons is intimately related to the fact that even
at short distances perturbation theory can fail to produce unique results. This
problem arises only in non-Abelian models and only starting at O(1/beta^2).Comment: 9 pages, 1 figure available on request from the author
Super-Instantons and the Reliability of Perturbation Theory in Non-Abelian Models
In dimension the low temperature behavior of systems enjoying a
continuous symmetry is dominated by super-instantons: classical configurations
of arbitrarily low energy. Perturbation theory in the background of a
super-instanton produces thermodynamic answers for the invariant Green's
functions that differ from the standard ones, but only in non-Abelian models
and only starting at . This effect modifies the -function
of the models and persists in the large limit of the models.Comment: 8 pages, plain LaTeX, MPI-Ph/93-87 and AZPH-TH/93-3
Super-Instantons, Perfect Actions, Finite Size Scaling and the Continuum Limit
We discuss some aspects of the continuum limit of some lattice models, in
particular the models. The continuum limit is taken either in an
infinite volume or in a box whose size is a fixed fraction of the infinite
volume correlation length. We point out that in this limit the fluctuations of
the lattice variables must be and thus restore the symmetry which may
have been broken by the boundary conditions (b.c.). This is true in particular
for the so-called super-instanton b.c. introduced earlier by us. This
observation leads to a criterion to assess how close a certain lattice
simulation is to the continuum limit and can be applied to uncover the true
lattice artefacts, present even in the so-called 'perfect actions'. It also
shows that David's recent claim that super-instanton b.c. require a different
renormalization must either be incorrect or an artefact of perturbation theory.Comment: 14 pages, latex, no figure
Fermion Determinants: Some Recent Analytic Results
The use of known analytic results for the continuum fermion determinants in
QCD and QED as benchmarks for zero lattice spacing extrapolations of lattice
fermion determinants is proposed. Specifically, they can be used as a check on
the universality hypothesis relating the continuum limits of the na\"{\i}ve,
staggered and Wilson fermion determinants.Comment: 8th Workshop on Non-Perturbative QCD, 7-11 June 2004, Pari
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