1,095 research outputs found
Identities in the Superintegrable Chiral Potts Model
We present proofs for a number of identities that are needed to study the
superintegrable chiral Potts model in the sector.Comment: LaTeX 2E document, using iopart.cls with iopams packages. 11 pages,
uses eufb10 and eurm10 fonts. Typeset twice! vs2: Two equations added. vs3:
Introduction adde
Excitation Spectrum and Correlation Functions of the Z_3-Chiral Potts Quantum Spin Chain
We study the excitation spectrum and the correlation functions of the Z_3-
chiral Potts model in the massive high-temperature phase using perturbation
expansions and numerical diagonalization. We are mainly interested in results
for general chiral angles but we consider also the superintegrable case. For
the parameter values considered, we find that the band structure of the low-
lying part of the excitation spectrum has the form expected from a
quasiparticle picture with two fundamental particles. Studying the N-dependence
of the spectrum, we confirm the stability of the second fundamental particle in
a limited range of the momentum, even when its energy becomes so high that it
lies very high up among the multiparticle scattering states. This is not a
phenomenon restricted to the superintegrable line. Calculating a
non-translationally invariant correlation function, we give evidence that it is
oscillating. Within our numerical accuracy we find a relation between the
oscillation length and the dip position of the momentum dispersion of the
lightest particle which seems to be quite independent of the chiral angles.Comment: 19 pages + 6 PostScript figures (LaTeX); BONN-TH-94-2
Eigenvectors in the Superintegrable Model I: sl_2 Generators
In order to calculate correlation functions of the chiral Potts model, one
only needs to study the eigenvectors of the superintegrable model. Here we
start this study by looking for eigenvectors of the transfer matrix of the
periodic tau_2(t)model which commutes with the chiral Potts transfer matrix. We
show that the degeneracy of the eigenspace of tau_2(t) in the Q=0 sector is
2^r, with r=(N-1)L/N when the size of the transfer matrix L is a multiple of N.
We introduce chiral Potts model operators, different from the more commonly
used generators of quantum group U-tilde_q(sl-hat(2)). From these we can form
the generators of a loop algebra L(sl(2)). For this algebra, we then use the
roots of the Drinfeld polynomial to give new explicit expressions for the
generators representing the loop algebra as the direct sum of r copies of the
simple algebra sl(2).Comment: LaTeX 2E document, 11 pages, 1 eps figure, using iopart.cls with
graphicx and iopams packages. v2: Appended text to title, added
acknowledgments and made several minor corrections v3: Added reference,
eliminated ambiguity, corrected a few misprint
Students appropriation of space in education outside the classroom : Some aspects on physical activity and health from a pilot Study with 5th-graders in Germany
In this article, we explore pupils’ appropriation of space in educational settings that take place outside the classroom. We first introduce the much-neglected concepts of place and space in educational contexts. Hereby, space expresses the abstract conception of geographical locations, which are then socio-culturally constructed as meaningful places.
We argue that places are very much qualified by atmospheres where the emotional experiences of the “objective” world are created within the subjects. Space on the other hand is the condition in which meaning is created in narrative discourses and where concrete pedagogical practice evolves. Hereby, pupils co-curate relational space by means of their mobility customs in (urban) open spaces. We then introduce education outside the classroom (EOtC) as a school form that facilitates and fosters the pupils’ space appropriation and offer finally some empirical insights from a case study in a German school. We show that EOtC increases not only the pupils’ physical activity (PA) levels during class but also their ability to better concentrate in relation to the learning environment. Many students use the physical freedom that comes with open learning spaces to interact with students that they rarely meet in closed classroom situations and to satisfy their need of movement during complicated understanding processes.
In education, space has been of interest since its earliest days, both physical and metaphorical (Oelkers, 1993, p. 634). However, after a long period of “space neglection” at the end of the 20th century, new interest in educational spaces has recently increased, at least at many German schools (Berndt, Kalisch, & Krüger, 2016). From an educational perspective, Students’ space appropriation, i.e. the different strategies to deal and bodily interact with the teaching environment, can be understood as an inherent process in every teaching situation. Hereby, space expresses the abstract conception of geographical locations or socio-culturally constructed and meaningful places.
This chapter will discuss the idea of space appropriation in educational settings, link it to an overview over research findings in Education Outside the Classroom and present evidence from a pilot study conducted in Heidelberg. Finally, future research directions will be discussed.acceptedVersio
Isothermal micro calorimetry – a new method for MIC determinations: results for 12 antibiotics and reference strains of E. coli and S. aureus
Antimicrobial susceptibility testing of microorganisms is performed by either disc diffusion or broth dilution tests. In clinical use, the tests are often still performed manually although automated systems exist. Most systems, however, are based on turbidometric methods which have well-known drawbacks
Spin operator matrix elements in the superintegrable chiral Potts quantum chain
We derive spin operator matrix elements between general eigenstates of the
superintegrable Z_N-symmetric chiral Potts quantum chain of finite length. Our
starting point is the extended Onsager algebra recently proposed by R.Baxter.
For each pair of spaces (Onsager sectors) of the irreducible representations of
the Onsager algebra, we calculate the spin matrix elements between the
eigenstates of the Hamiltonian of the quantum chain in factorized form, up to
an overall scalar factor. This factor is known for the ground state Onsager
sectors. For the matrix elements between the ground states of these sectors we
perform the thermodynamic limit and obtain the formula for the order
parameters. For the Ising quantum chain in a transverse field (N=2 case) the
factorized form for the matrix elements coincides with the corresponding
expressions obtained recently by the Separation of Variables Method.Comment: 24 pages, 1 figur
Physics beyond quasi-particles: Spectrum and completeness of the 3 state superintegrable chiral Potts model
We find the rules which count the energy levels of the 3 state
superintegrable chiral Potts model and demonstrate that these rules are
complete. We then derive the complete spectrum of excitations in the
thermodynamic limit in the massive phase and demonstrate the existence of
excitations which do not have a quasi-particle form. The physics of these
excitations is compared with the BCS superconductivity spectrum and the
counting rules are compared with the closely related XXZ spin chain.Comment: 39 page
The Onsager Algebra Symmetry of -matrices in the Superintegrable Chiral Potts Model
We demonstrate that the -matrices in the superintegrable chiral
Potts model possess the Onsager algebra symmetry for their degenerate
eigenvalues. The Fabricius-McCoy comparison of functional relations of the
eight-vertex model for roots of unity and the superintegrable chiral Potts
model has been carefully analyzed by identifying equivalent terms in the
corresponding equations, by which we extract the conjectured relation of
-operators and all fusion matrices in the eight-vertex model corresponding
to the -relation in the chiral Potts model.Comment: Latex 21 pages; Typos added, References update
Nonequilibrium Forces Between Neutral Atoms Mediated by a Quantum Field
We study all known and as yet unknown forces between two neutral atoms,
modeled as three dimensional harmonic oscillators, arising from mutual
influences mediated by an electromagnetic field but not from their direct
interactions. We allow as dynamical variables the center of mass motion of the
atom, its internal degrees of freedom and the quantum field treated
relativistically. We adopt the method of nonequilibrium quantum field theory
which can provide a first principle, systematic and unified description
including the intrinsic field fluctuations and induced dipole fluctuations. The
inclusion of self-consistent back-actions makes possible a fully dynamical
description of these forces valid for general atom motion. In thermal
equilibrium we recover the known forces -- London, van der Waals and
Casimir-Polder forces -- between neutral atoms in the long-time limit but also
discover the existence of two new types of interatomic forces. The first, a
`nonequilibrium force', arises when the field and atoms are not in thermal
equilibrium, and the second, which we call an `entanglement force', originates
from the correlations of the internal degrees of freedom of entangled atoms.Comment: 16 pages, 2 figure
Factorized finite-size Ising model spin matrix elements from Separation of Variables
Using the Sklyanin-Kharchev-Lebedev method of Separation of Variables adapted
to the cyclic Baxter--Bazhanov--Stroganov or -model, we derive
factorized formulae for general finite-size Ising model spin matrix elements,
proving a recent conjecture by Bugrij and Lisovyy
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