15 research outputs found
Multi-point local height probabilities of the CSOS model within the algebraic Bethe Ansatz framework
We study the local height probabilities of the exactly solvable cyclic
solid-on-solid model within the algebraic Bethe Ansatz framework. We more
specifically consider multi-point local height probabilities at adjacent sites
on the lattice. We derive multiple integral representations for these
quantities at the thermodynamic limit, starting from finite-size expressions
for the corresponding multi-point matrix elements in the Bethe basis as sums of
determinants of elliptic functions.Comment: 39 page
Antiperiodic dynamical 6-vertex model by separation of variables II: Functional equations and form factors
We pursue our study of the antiperiodic dynamical 6-vertex model using
Sklyanin's separation of variables approach, allowing in the model new possible
global shifts of the dynamical parameter. We show in particular that the
spectrum and eigenstates of the antiperiodic transfer matrix are completely
characterized by a system of discrete equations. We prove the existence of
different reformulations of this characterization in terms of functional
equations of Baxter's type. We notably consider the homogeneous functional
- equation which is the continuous analog of the aforementioned discrete
system and show, in the case of a model with an even number of sites, that the
complete spectrum and eigenstates of the antiperiodic transfer matrix can
equivalently be described in terms of a particular class of its -solutions,
hence leading to a complete system of Bethe equations. Finally, we compute the
form factors of local operators for which we obtain determinant representations
in finite volume.Comment: 52 page
Antiperiodic dynamical 6-vertex model I: Complete spectrum by SOV, matrix elements of the identity on separate states and connections to the periodic 8-vertex model
The spin-1/2 highest weight representations of the dynamical 6-vertex and the
standard 8-vertex Yang-Baxter algebra on a finite chain are considered in this
paper. For the antiperiodic dynamical 6-vertex transfer matrix defined on
chains with an odd number of sites, we adapt the Sklyanin's quantum separation
of variable (SOV) method and explicitly construct SOV representations from the
original space of representations. We provide the complete characterization of
eigenvalues and eigenstates proving also the simplicity of its spectrum.
Moreover, we characterize the matrix elements of the identity on separated
states by determinant formulae. The matrices entering in these determinants
have elements given by sums over the SOV spectrum of the product of the
coefficients of separate states. This SOV analysis is not reduced to the case
of the elliptic roots of unit and the results here derived define the required
setup to extend to the dynamical 6-vertex model the approach recently developed
in [1]-[5] to compute the form factors of the local operators in the SOV
framework, these results will be presented in a future publication. For the
periodic 8-vertex transfer matrix, we prove that its eigenvalues have to
satisfy a fixed system of equations. In the case of a chain with an odd number
of sites, this system of equations is the same entering in the SOV
characterization of the antiperiodic dynamical 6-vertex transfer matrix
spectrum. This implies that the set of the periodic 8-vertex eigenvalues is
contained in the set of the antiperiodic dynamical 6-vertex eigenvalues. A
criterion is introduced to find simultaneous eigenvalues of these two transfer
matrices and associate to any of such eigenvalues one nonzero eigenstate of the
periodic 8-vertex transfer matrix by using the SOV results. Moreover, a
preliminary discussion on the degeneracy of the periodic 8-vertex spectrum is
also presented.Comment: 36 pages, main modifications in section 3 and one appendix added, no
result modified for the dynamical 6-vertex transfer matrix spectrum and the
matrix elements of identity on separate states for chains with an odd number
of site
Multi-point local height probabilities of the CSOS model within the algebraic Bethe ansatz framework
Acquired visual field defects rehabilitation: critical review and perspectives
Visual field deficit (VFD) is one of the most commonly observed symptoms following brain injury. Persistent VFD and defective exploratory oculomotor scanning patterns often cause severe impairment in daily activities, particularly as regards visual exploration and reading. Homonymous hemianopia is consequently a powerful negative predictor of patient outcome. In spite of these quantitative and qualitative factors, there currently exists no consensus on rehabilitative therapy and treatment. Different approaches have nevertheless been developed, all of them having one therapeutic principle in common; repeated practice of a specific visual task, with the hope/expectation that improved performance will extend to a wide range of ecologically useful visual functions. The four main available methods aim at replacing part of the intact visual field with part of the damaged visual field (optical therapy using prisms), at partially restoring the lost visual field region (restorative therapies), at stimulating detection capacities in the blind field (stimulation or blindsight) or at substituting for the lost region by reorganizing the control of visual information processing and eye movements (compensatory therapies). This review explores the key data relative to these different approaches in terms of behavioral or imagery results. It also aims at critically analyzing the advantages and limits of each one. The importance of strict assessment in terms of deficiencies or disabilities is underlined. Finally, upon consideration of these data taken as a whole, it is suggested that efficient treatment would probably have to associate general components and more specific elements, according to what may be done with regard to other aspects of cognitive rehabilitation