31 research outputs found
Nuclearity and Thermal States in Conformal Field Theory
We introduce a new type of spectral density condition, that we call
L^2-nuclearity. One formulation concerns lowest weight unitary representations
of SL(2,R) and turns out to be equivalent to the existence of characters. A
second formulation concerns inclusions of local observable von Neumann algebras
in Quantum Field Theory. We show the two formulations to agree in chiral
Conformal QFT and, starting from the trace class condition for the semigroup
generated by the conformal Hamiltonian L_0, we infer and naturally estimate the
Buchholz-Wichmann nuclearity condition and the (distal) split property. As a
corollary, if L_0 is log-elliptic, the Buchholz-Junglas set up is realized and
so there exists a beta-KMS state for the translation dynamics on the net of
C*-algebras for every inverse temperature beta>0. We include further
discussions on higher dimensional spacetimes. In particular, we verify that
L^2-nuclearity is satisfied for the scalar, massless Klein-Gordon field.Comment: 37 pages, minor correction
Modular Structure and Duality in Conformal Quantum Field Theory
Making use of a recent result of Borchers, an algebraic version of the
Bisognano-Wichmann theorem is given for conformal quantum field theories, i.e.
the Tomita-Takesaki modular group associated with the von Neumann algebra of a
wedge region and the vacuum vector concides with the evolution given by the
rescaled pure Lorentz transformations preserving the wedge. A similar geometric
description is valid for the algebras associated with double cones. Moreover
essential duality holds on the Minkowski space , and Haag duality for double
cones holds provided the net of local algebras is extended to a pre-cosheaf on
the superworld , i.e. the universal covering of the Dirac-Weyl
compactification of . As a consequence a PCT symmetry exists for any
algebraic conformal field theory in even space-time dimension. Analogous
results hold for a Poincar\'e covariant theory provided the modular groups
corresponding to wedge algebras have the expected geometrical meaning and the
split property is satisfied. In particular the Poincar\'e representation is
unique in this case.Comment: 23 pages, plain TeX, TVM26-12-199
The Conformal Spin and Statistics Theorem
We prove the equality between the statistics phase and the conformal
univalence for a superselection sector with finite index in Conformal Quantum
Field Theory on . A relevant point is the description of the PCT symmetry
and the construction of the global conjugate charge.Comment: plain tex, 22 page
Jorge A. Swieca's contributions to quantum field theory in the 60s and 70s and their relevance in present research
After revisiting some high points of particle physics and QFT of the two
decades from 1960 to 1980, I comment on the work by Jorge Andre Swieca. I
explain how it fits into the quantum field theory during these two decades and
draw attention to its relevance to the ongoing particle physics research. A
particular aim of this article is to direct thr readers mindfulness to the
relevance of what at the time of Swieca was called "the Schwinger Higgs
screening mechanism". which, together with recent ideas which generalize the
concept of gauge theories, has all the ingredients to revolutionize the issue
of gauge theories and the standard model.Comment: 49 pages, expansion and actualization of text, improvement of
formulations and addition of many references to be published in EPJH -
Historical Perspectives on Contemporary Physic