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Date: Mon, 25 Feb 2002 16:46:05 -0300
From: Ivanilda Gomes Ferreira <iva@cbpf.br>
Subject: EVENTOS DA SEMANA
EVENTOS DA SEMANA
SEMINARIO DO CMF
DIA: 26/02/2002 HORARIO: 10:30H
LOCAL: Auditório do 3 andar
Prof.:Alberto Robledo
Instituto de Fisica, Universidad Nacional Autonoma de Mexico,
Título:The renormalization group and optimization of non-extensive
entropy:
Criticality in non-linear one-dimensional maps
Resumo:
We examine the pitchfork and tangent bifurcations in unimodal maps to
illustrate a connection between renormalization group (RG) fixed points
and entropy extremal properties. We observe that the exact RG solution
for the tangent bifurcation is also applicable to the period doubling
cascade and assess its physical meaning. Since the expression for the
fixed-point map can be put into the form of the non-extensive
expressions for the temporal evolution of phase-space volume and
sensitivity of initial conditions, we conclude that the map critical
points possess the properties of this formalism. The degrees of
non-extensivity q and non-linearity z are equivalent and the critical
Lyapunov exponent is the leading map expansion coefficient. The
universality of the RG solution makes this interpretation inclusive to
all one-dimensional maps of non-linearity z>1. We provide too a
description of the attractor at the edge of chaos in terms of its
combined RG and entropy properties.
SEMINÁRIO CMF
DATA: 28 DE FEVEREIRO DE 2002 (quinta-feira) HORÁRIO: 15:00h
SEMINARISTA: PROF. BERT SCHROER
Institut für Theor. Phisyk – Alemanha e CCP -
CBPF
TEMA: AREA LAW FOR “LOCALIZATION ENTROPY”
IN LOCAL QUANTUM PHYSICS
Resumo:
It has been known for 2 decades that besides the standard “heat bath”
thermodynamics (whose microscopic description is based on Gibbs ensemble
formulas) there are also thermal manifestations of quantum matter
enclosed behind an event horizon as encountered in the setting of
Hawking’s black holes. This interesting phenomenon has a kind of
Gedankenexperiment-analog in terms of Unruh’s accelerated observer
(whose causally accessible world becomes restricted to the Rindler wedge
region). It is easy to see that the vacuum restricted to a Rindler
wedge behaves (loss of information) as a thermal state at a Hawking
temperature which depends on the acceleration. In such a situation one
expects to encounter also other aspects of thermal physics as entropy.
Classical ideas suggest that the entropy associated with event horizons
should follow an area law (Bekenstein). The quantum aspects of this
entropy turned out to be a much more difficult problem, but very
recently the local quantum physical origin of this behavior was
explained in terms of a very general “transverse tensor factorization
property”of lightfront quantum field theory (B.Schroer, hep-th/0111188,
hep-th/0202085). The physical-intuitive content of this result will be
the main subject of this seminar.
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