54 research outputs found
Finite size effects in perturbed boundary conformal field theories
We discuss the finite-size properties of a simple integrable quantum field
theory in 1+1 dimensions with non-trivial boundary conditions. Novel
off-critical identities between cylinder partition functions of models with
differing boundary conditions are derived.Comment: 7 pages, 11 figures, JHEP proceedings style. Uses epsfig, amssymb.
Talk given at the conference `Nonperturbative Quantum Effects 2000', Pari
On the deformability of Heisenberg algebras
Based on the vanishing of the second Hochschild cohomology group of the
enveloping algebra of the Heisenberg algebra it is shown that differential
algebras coming from quantum groups do not provide a non-trivial deformation of
quantum mechanics. For the case of a q-oscillator there exists a deforming map
to the classical algebra. It is shown that the differential calculus on quantum
planes with involution, i.e. if one works in position-momentum realization, can
be mapped on a q-difference calculus on a commutative real space. Although this
calculus leads to an interesting discretization it is proved that it can be
realized by generators of the undeformed algebra and does not posess a proper
group of global transformations.Comment: 16 pages, latex, no figure
Selfdual 2-form formulation of gravity and classification of energy-momentum tensors
It is shown how the different irreducibility classes of the energy-momentum
tensor allow for a Lagrangian formulation of the gravity-matter system using a
selfdual 2-form as a basic variable. It is pointed out what kind of
difficulties arise when attempting to construct a pure spin-connection
formulation of the gravity-matter system. Ambiguities in the formulation
especially concerning the need for constraints are clarified.Comment: title changed, extended versio
A q-Lorentz Algebra From q-Deformed Harmonic Oscillators
A mapping between the operators of the bosonic oscillator and the Lorentz
rotation and boost generators is presented. The analog of this map in the
-deformed regime is then applied to -deformed bosonic oscillators to
generate a -deformed Lorentz algebra, via an inverse of the standard chiral
decomposition. A fundamental representation, and the co-algebra structure, are
given, and the generators are reformulated into -deformed rotations and
boosts. Finally, a relation between the -boson operators and a basis of
-deformed Minkowski coordinates is noted.Comment: 20 pages, REVTeX, uses aps.st
Wave function renormalization constants and one-particle form factors in Toda field theories
We apply the method of angular quantization to calculation of the wave
function renormali- zation constants in affine Toda quantum field
theories. A general formula for the wave function renormalization constants in
ADE Toda field theories is proposed. We also calculate all one-particle form
factors and some of the two-particle form factors of an exponential field.Comment: harvmac, 28 pages, 2 eps figures, misprints correcte
Reflection equations and q-Minkowski space algebras
We express the defining relations of the -deformed Minkowski space algebra
as well as that of the corresponding derivatives and differentials in the form
of reflection equations. This formulation encompasses the covariance properties
with respect the quantum Lorentz group action in a straightforward way.Comment: 10 page
Solutions of Klein--Gordon and Dirac equations on quantum Minkowski spaces
Covariant differential calculi and exterior algebras on quantum homogeneous
spaces endowed with the action of inhomogeneous quantum groups are classified.
In the case of quantum Minkowski spaces they have the same dimensions as in the
classical case. Formal solutions of the corresponding Klein--Gordon and Dirac
equations are found. The Fock space construction is sketched.Comment: 21 pages, LaTeX file, minor change
Ultraviolet cut off and Bosonic Dominance
We rederive the thermodynamical properties of a non interacting gas in the
presence of a minimal uncertainty in length. Apart from the phase space measure
which is modified due to a change of the Heisenberg uncertainty relations, the
presence of an ultraviolet cut-off plays a tremendous role.
The theory admits an intrinsic temperature above which the fermion
contribution to energy density, pressure and entropy is negligible.Comment: 12 pages in revtex, 2 figures. Some coefficients have been changed in
the A_2 model and two references adde
Perturbed Defects and T-Systems in Conformal Field Theory
Defect lines in conformal field theory can be perturbed by chiral defect
fields. If the unperturbed defects satisfy su(2)-type fusion rules, the
operators associated to the perturbed defects are shown to obey functional
relations known from the study of integrable models as T-systems. The procedure
is illustrated for Virasoro minimal models and for Liouville theory.Comment: 24 pages, 13 figures; v2: typos corrected, in particular in (2.10)
and app. A.2, version to appear in J.Phys.
Exact Form Factors in Integrable Quantum Field Theories: the Sine-Gordon Model
We provide detailed arguments on how to derive properties of generalized form
factors, originally proposed by one of the authors (M.K.) and Weisz twenty
years ago, solely based on the assumption of "minimal analyticity" and the
validity of the LSZ reduction formalism. These properties constitute
consistency equations which allow the explicit evaluation of the n-particle
form factors once the scattering matrix is known. The equations give rise to a
matrix Riemann-Hilbert problem. Exploiting the "off-shell" Bethe ansatz we
propose a general formula for form factors for an odd number of particles. For
the Sine-Gordon model alias the massive Thirring model we exemplify the general
solution for several operators. We carry out a consistency check for the
solution of the three particle form factor against the Thirring model
perturbation theory and thus confirm the general formalism.Comment: 55 pages, 7 figures, LaTe
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