15,538 research outputs found

    Surface Free Energies, Interfacial Tensions and Correlation Lengths of the ABF Models

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    The surface free energies, interfacial tensions and correlation lengths of the Andrews-Baxter-Forrester models in regimes III and IV are calculated with fixed boundary conditions. The interfacial tensions are calculated between arbitrary phases and are shown to be additive. The associated critical exponents are given by 2−αs=μ=ν2-\alpha_s=\mu=\nu with ν=(L+1)/4\nu=(L+1)/4 in regime III and 4−2αs=μ=ν4-2\alpha_s=\mu=\nu with ν=(L+1)/2\nu=(L+1)/2 in regime IV. Our results are obtained using general commuting transfer matrix and inversion relation methods that may be applied to other solvable lattice models.Comment: 21 pages, LaTeX 2e, requires the amsmath packag

    Interaction-Round-a-Face Models with Fixed Boundary Conditions: The ABF Fusion Hierarchy

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    We use boundary weights and reflection equations to obtain families of commuting double-row transfer matrices for interaction-round-a-face models with fixed boundary conditions. In particular, we consider the fusion hierarchy of the Andrews-Baxter-Forrester models, for which we find that the double-row transfer matrices satisfy functional equations with an su(2) structure.Comment: 48 pages, LaTeX, requires about 79000 words of TeX memory. Submitted to J. Stat. Phy

    Integrals of Motion for Critical Dense Polymers and Symplectic Fermions

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    We consider critical dense polymers L(1,2){\cal L}(1,2). We obtain for this model the eigenvalues of the local integrals of motion of the underlying Conformal Field Theory by means of Thermodynamic Bethe Ansatz. We give a detailed description of the relation between this model and Symplectic Fermions including the indecomposable structure of the transfer matrix. Integrals of motion are defined directly on the lattice in terms of the Temperley Lieb Algebra and their eigenvalues are obtained and expressed as an infinite sum of the eigenvalues of the continuum integrals of motion. An elegant decomposition of the transfer matrix in terms of a finite number of lattice integrals of motion is obtained thus providing a reason for their introduction.Comment: 53 pages, version accepted for publishing on JSTA

    Refined conformal spectra in the dimer model

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    Working with Lieb's transfer matrix for the dimer model, we point out that the full set of dimer configurations may be partitioned into disjoint subsets (sectors) closed under the action of the transfer matrix. These sectors are labelled by an integer or half-integer quantum number we call the variation index. In the continuum scaling limit, each sector gives rise to a representation of the Virasoro algebra. We determine the corresponding conformal partition functions and their finitizations, and observe an intriguing link to the Ramond and Neveu-Schwarz sectors of the critical dense polymer model as described by a conformal field theory with central charge c=-2.Comment: 44 page

    Ethnic differences in height growth trajectories and early life factors: Findings from the UK Millennium Cohort Study

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    Height growth is an important biomarker for early life exposures that influence later disease risk. Previous studies show that ethnic minority children in the UK tend to be born lighter but experience more rapid infancy growth than White peers. However, whether subsequent child-to-adolescent growth differs by ethnic group is insufficiently understood. We used the data from 15,239 singletons in the UK Millennium Cohort Study and applied mixed-effects cubic growth models to examine ethnic differences in height trajectories between 3y and 14y. Models were subsequently adjusted for potential early life explanatory factors. Compared with White counterparts, South Asian children had lower birthweight and shorter parents on average, but were slightly taller at 3y by 0.5cm [95% CI: 0.2–0.9] and had comparable childhood and adolescent trajectories, except that girls had a slower growth in adolescence. Height of South Asians relative to White children increased after adjusting for birthweight (taller by 1.3cm at 3y). Black African/Caribbeans were taller than White children at all ages between 3y and 14y (at 3y boys: 2.2cm, 1.2–2.7; girls: 3.2cm, 2.6–3.8) with height differences widening in childhood and reducing in adolescence. Adjustment for potential explanatory factors did not alter these differences. Despite having lower birthweight, contemporary UK South Asian children had comparable child-to-adolescent growth as White children. Black African/Caribbeans were considerably taller than other ethnic groups. Future research is needed in understanding the role of genetic and other environmental factors (such as diet) in these distinct growth patterns across ethnic groups and their health implications

    Content Area Reading Preparation: Effectiveness of Four Methods of Instruction

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    The belief that secondary content teachers should have content reading as a course in their pre-service education is an idea that is gaining increasing acceptance. Surveys examining certification requirements show that an increasing number of states mandate a course in reading for secondary certification (Bader, 1975; Lamberg, 1978). This trend is also reflected in increased numbers of teacher training institutions that are now offering a content area reading course for their undergraduate secondary education majors, as compared to ten years ago

    Cancer And Premature Mortality In Ireland: An Employer's Perspective Following The Friction Cost Approach.

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    Cancer is the second leading cause of death in Ireland accounting for approximately 30% of all deaths. Of these, almost a third arise in those of working age. As well as the public health burden, cancer also imposes economic costs on society in general and employers in particular. This study measured the productivity costs associated with cancer-related premature mortality from an employer’s perspective in Ireland

    On the structure of the scalar mesons f0(975)f_0(975) and a0(980)a_0(980)

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    We investigate the structure of the scalar mesons f0(975)f_0(975) and a0(980)a_0(980) within realistic meson-exchange models of the ππ\pi\pi and πη\pi\eta interactions. Starting from a modified version of the J\"ulich model for ππ\pi\pi scattering we perform an analysis of the pole structure of the resulting scattering amplitude and find, in contrast to existing models, a somewhat large mass for the f0(975)f_0(975) (mf0=1015m_{f_0}=1015 MeV, Γf0=30\Gamma_{f_0}=30 MeV). It is shown that our model provides a description of J/ψ→ϕππ/ϕKKJ/\psi\rightarrow\phi\pi\pi/\phi KK data comparable in quality with those of alternative models. Furthermore, the formalism developed for the ππ\pi\pi system is consistently extended to the πη\pi\eta interaction leading to a description of the a0(980)a_0(980) as a dynamically generated threshold effect (which is therefore neither a conventional qq‾q\overline{q} state nor a KK‾K\overline{K} bound state). Exploring the corresponding pole position the a0(980)a_0(980) is found to be rather broad (ma0=991m_{a_0}=991 MeV, Γa0=202\Gamma_{a_0}=202 MeV). The experimentally observed smaller width results from the influence of the nearby KK‾K\overline{K} threshold on this pole.Comment: 25 pages, 15 Postscript figure
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