539 research outputs found
Looking beyond the Thermal Horizon: Hidden Symmetries in Chiral Models
In thermal states of chiral theories, as recently investigated by H.-J.
Borchers and J. Yngvason, there exists a rich group of hidden symmetries. Here
we show that this leads to a radical converse of of the Hawking-Unruh
observation in the following sense. The algebraic commutant of the algebra
associated with a (heat bath) thermal chiral system can be used to reprocess
the thermal system into a ground state system on a larger algebra with a larger
localization space-time. This happens in such a way that the original system
appears as a kind of generalized Unruh restriction of the ground state sytem
and the thermal commutant as being transmutated into newly created ``virgin
space-time region'' behind a horizon. The related concepts of a ``chiral
conformal core'' and the possibility of a ``blow-up'' of the latter suggest
interesting ideas on localization of degrees of freedom with possible
repercussion on how to define quantum entropy of localized matter content in
Local Quantum Physics.Comment: 17 pages, tcilatex, still more typos removed and one reference
correcte
The Pivotal Role of Causality in Local Quantum Physics
In this article an attempt is made to present very recent conceptual and
computational developments in QFT as new manifestations of old and well
establihed physical principles. The vehicle for converting the
quantum-algebraic aspects of local quantum physics into more classical
geometric structures is the modular theory of Tomita. As the above named
laureate to whom I have dedicated has shown together with his collaborator for
the first time in sufficient generality, its use in physics goes through
Einstein causality. This line of research recently gained momentum when it was
realized that it is not only of structural and conceptual innovative power (see
section 4), but also promises to be a new computational road into
nonperturbative QFT (section 5) which, picturesquely speaking, enters the
subject on the extreme opposite (noncommutative) side.Comment: This is a updated version which has been submitted to Journal of
Physics A, tcilatex 62 pages. Adress: Institut fuer Theoretische Physik
FU-Berlin, Arnimallee 14, 14195 Berlin presently CBPF, Rua Dr. Xavier Sigaud
150, 22290-180 Rio de Janeiro, Brazi
Functional integral approach to multipoint correlators in 2d critical systems
We extend a previously developed technique for computing spin-spin critical
correlators in the 2d Ising model, to the case of multiple correlations. This
enables us to derive Kadanoff-Ceva's formula in a simple and elegant way. We
also exploit a doubling procedure in order to evaluate the critical exponent of
the polarization operator in the Baxter model. Thus we provide a rigorous proof
of the relation between different exponents, in the path-integral framework.Comment: 10 pages, LaTex, no figure
Comment on: Modular Theory and Geometry
In this note we comment on part of a recent article by B. Schroer and H.-W.
Wiesbrock. Therein they calculate some new modular structure for the
U(1)-current-algebra (Weyl-algebra). We point out that their findings are true
in a more general setting. The split-property allows an extension to
doubly-localized algebras.Comment: 13 pages, corrected versio
Applications of Canonical Transformations
Canonical transformations are defined and discussed along with the
exponential, the coherent and the ultracoherent vectors. It is shown that the
single-mode and the -mode squeezing operators are elements of the group of
canonical transformations. An application of canonical transformations is made,
in the context of open quantum systems, by studying the effect of squeezing of
the bath on the decoherence properties of the system. Two cases are analyzed.
In the first case the bath consists of a massless bosonic field with the bath
reference states being the squeezed vacuum states and squeezed thermal states
while in the second case a system consisting of a harmonic oscillator
interacting with a bath of harmonic oscillators is analyzed with the bath being
initially in a squeezed thermal state.Comment: 14 page
New Concepts in Particle Physics from Solution of an Old Problem
Recent ideas on modular localization in local quantum physics are used to
clarify the relation between on- and off-shell quantities in particle physics;
in particular the relation between on-shell crossing symmetry and off-shell
Einstein causality. Among the collateral results of this new nonperturbative
approach are profound relations between crossing symmetry of particle physics
and Hawking-Unruh like thermal aspects (KMS property, entropy attached to
horizons) of quantum matter behind causal horizons, aspects which hitherto were
exclusively related with Killing horizons in curved spacetime rather than with
localization aspects in Minkowski space particle physics. The scope of this
modular framework is amazingly wide and ranges from providing a conceptual
basis for the d=1+1 bootstrap-formfactor program for factorizable d=1+1 models
to a decomposition theory of QFT's in terms of a finite collection of unitarily
equivalent chiral conformal theories placed a specified relative position
within a common Hilbert space (in d=1+1 a holographic relation and in higher
dimensions more like a scanning). The new framework gives a spacetime
interpretation to the Zamolodchikov-Faddeev algebra and explains its thermal
aspects.Comment: In this form it will appear in JPA Math Gen, 47 pages tcilate
Mutually local fields from form factors
We compare two different methods of computing form factors. One is the well
established procedure of solving the form factor consistency equations and the
other is to represent the field content as well as the particle creation
operators in terms of fermionic Fock operators. We compute the corresponding
matrix elements for the complex free fermion and the Federbush model. The
matrix elements only satisfy the form factor consistency equations involving
anyonic factors of local commutativity when the corresponding operators are
local. We carry out the ultraviolet limit, analyze the momentum space cluster
properties and demonstrate how the Federbush model can be obtained from the
-homogeneous sine-Gordon model. We propose a new class of Lagrangians
which constitute a generalization of the Federbush model in a Lie algebraic
fashion. For these models we evaluate the associated scattering matrices from
first principles, which can alternatively also be obtained in a certain limit
of the homogeneous sine-Gordon models.Comment: 16 pages Late
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