Wave function renormalization constants and one-particle form factors in Dl(1)D_{l}^{(1)} Toda field theories

We apply the method of angular quantization to calculation of the wave function renormali- zation constants in $D_{l}^{(1)}$ 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

Capillary wave turbulence on a spherical fluid surface in low gravity

We report the observation of capillary wave turbulence on the surface of a fluid layer in a low-gravity environment. In such conditions, the fluid covers all the internal surface of the spherical container which is submitted to random forcing. The surface wave amplitude displays power-law spectrum over two decades in frequency, corresponding to wavelength from $mm$ to a few $cm$. This spectrum is found in roughly good agreement with wave turbulence theory. Such a large scale observation without gravity waves has never been reached during ground experiments. When the forcing is periodic, two-dimensional spherical patterns are observed on the fluid surface such as subharmonic stripes or hexagons with wavelength satisfying the capillary wave dispersion relation

Hermitian analyticity versus Real analyticity in two-dimensional factorised S-matrix theories

The constraints implied by analyticity in two-dimensional factorised S-matrix theories are reviewed. Whenever the theory is not time-reversal invariant, it is argued that the familiar condition of `Real analyticity' for the S-matrix amplitudes has to be superseded by a different one known as `Hermitian analyticity'. Examples are provided of integrable quantum field theories whose (diagonal) two-particle S-matrix amplitudes are Hermitian analytic but not Real analytic. It is also shown that Hermitian analyticity is consistent with the bootstrap equations and that it ensures the equivalence between the notion of unitarity in the quantum group approach to factorised S-matrices and the genuine unitarity of the S-matrix.Comment: 9 pages, LaTeX file. The comments about unitarity in affine Toda theories have been improved. The basis dependence of the Hermitian analyticity conditions is discusse

Integrable Quantum Field Theories with Unstable Particles

A new family of S-matrix theories with resonance poles is constructed and conjectured to correspond to the Homogeneous sine-Gordon theories associated with simply laced compact Lie groups, where some of the resonance poles can be traced to the presence of unstable particles in the spectrum. These theories are unitary in the usual S S^\dagger =1 sense, they are not parity invariant, and they exhibit continuous coupling constants that determine both the mass spectrum of stable particles and the masses and the position of the resonance poles.Comment: One reference added, 12 pages, LaTeX fil