Different Scenarios for Critical Glassy Dynamics

We study the role of different terms in the $N$-body potential of glass forming systems on the critical dynamics near the glass transition. Using a simplified spin model with quenched disorder, where the different terms of the real $N$-body potential are mapped into multi-spin interactions, we identified three possible scenarios. For each scenario we introduce a ``minimal'' model representative of the critical glassy dynamics near, both above and below, the critical transition lin e. For each ``minimal'' model we discuss the low temperature equilibrium dynamics.Comment: Completely revised version, 8 pages, 5 figures, typeset using EURO-LaTeX, Europhysics Letters (in press

Boundary K-Matrices for the Six Vertex and the n(2n-1) A_{n-1} Vertex Models

Boundary conditions compatible with integrability are obtained for two dimensional models by solving the factorizability equations for the reflection matrices $K^{\pm}(\theta)$. For the six vertex model the general solution depending on four arbitrary parameters is found. For the $A_{n-1}$ models all diagonal solutions are found. The associated integrable magnetic Hamiltonians are explicitly derived.Comment: 9 pages,latex, LPTHE-PAR 92-4

Search for the Θˉ−→\bar{\Theta}^- \to K−^- nˉ\bar{n} with PHENIX

The PHENIX experiment at RHIC should be sensitive to decays of the the anti--pentaquark $\bar{\Theta}^-$ via the K$^-$ $\bar{n}$ channel. Charged kaons can be identified using the standard tracking and time of flight up to a momentum of 1.5 GeV/c. Anti--neutron candidates are detected via their annihilation signal in the highly segmented electromagnetic calorimeter (EMCal). In order to assess the quality of the anti--neutron identification we reconstruct the $\bar{\Sigma} \to \bar{n}\pi$. As an additional crosscheck the invariant mass of K$^+$ $\bar{n}$ is reconstructed where no resonance in the pentaquark mass range is expected. At the present time no enhancement at the expected pentaquark mass is observed in dAu collisions at $\sqrt{s_{NN}} = 200 GeV.Comment: 4 pages 5 figures contribution to the proceedings of the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter, Oakland, January 11-17, 2004). To appear in the proceedings (Journal of Physics G

Primordial Entropy Production and Lambda-driven Inflation from Quantum Einstein Gravity

We review recent work on renormalization group (RG) improved cosmologies based upon a RG trajectory of Quantum Einstein Gravity (QEG) with realistic parameter values. In particular we argue that QEG effects can account for the entire entropy of the present Universe in the massless sector and give rise to a phase of inflationary expansion. This phase is a pure quantum effect and requires no classical inflaton field.Comment: 12 pages, 4 figures, IGCG-07 Pun

Neutron Transversity at Jefferson Lab

Nucleon transversity and single transverse spin asymmetries have been the recent focus of large efforts by both theorists and experimentalists. On-going and planned experiments from HERMES, COMPASS and RHIC are mostly on the proton or the deuteron. Presented here is a planned measurement of the neutron transversity and single target spin asymmetries at Jefferson Lab in Hall A using a transversely polarized $^3$He target. Also presented are the results and plans of other neutron transverse spin experiments at Jefferson Lab. Finally, the factorization for semi-inclusive DIS studies at Jefferson Lab is discussed.Comment: 8 pages, 2 figures, proceedings of Como Transversity05 Worksho

Elliptic and triangular flow of identified particles at ALICE

We report on the first measurements of elliptic and triangular flow for charged pions, kaons and anti-protons in lead-lead collisions at 2.76 TeV measured with the ALICE detector at the LHC. We compare the observed mass splitting of differential elliptic flow at LHC energies to RHIC measurements at lower energies and theory predictions. We test the quark coalescence picture with the quark number scaling of elliptic and triangular flow.Comment: 4 pages, 5 figures, Quark Matter 2011 conference proceeding

Magnetization plateaux in the classical Shastry-Sutherland lattice

We investigated the classical Shastry-Sutherland lattice under an external magnetic field in order to understand the recently discovered magnetization plateaux in the rare-earth tetraborides compounds RB$_4$. A detailed study of the role of thermal fluctuations was carried out by mean of classical spin waves theory and Monte-Carlo simulations. Magnetization quasi-plateaux were observed at 1/3 of the saturation magnetization at non zero temperature. We showed that the existence of these quasi-plateaux is due to an entropic selection of a particular collinear state. We also obtained a phase diagram that shows the domains of existence of different spin configurations in the magnetic field versus temperature plane.Comment: 4 pages, proceedings of HFM200

Flux quantization and superfluid weight in doped antiferromagnets

Doped antiferromagnets, described by a t-t'-J model and a suitable 1/N expansion, exhibit a metallic phase-modulated antiferromagnetic ground state close to half-filling. Here we demonstrate that the energy of latter state is an even periodic function of the external magnetic flux threading the square lattice in an Aharonov-Bohm geometry. The period is equal to the flux quantum $\Phi_{0}=2\pi\hbar c/q$ entering the Peierls phase factor of the hopping matrix elements. Thus flux quantization and a concomitant finite value of superfluid weight D_s occur along with metallic antiferromagnetism. We argue that in the context of the present effective model, whereby carriers are treated as hard-core bosons, the charge q in the associated flux quantum might be set equal to 2e. Finally, the superconducting transition temperature T_c is related to D_s linearly, in accordance to the generic Kosterlitz-Thouless type of transition in a two-dimensional system, signaling the coherence of the phase fluctuations of the condensate. The calculated dependence of T_c on hole concentration is qualitatively similar to that observed in the high-temperature superconducting cuprates.Comment: 5 pages, 2 figures, to be published in J. Phys. Condens. Matte

Parenting ‘gifted and talented’ children in urban areas: Parents' voices

This is the author's accepted manuscript. The final published article is available from the link below. Copyright © 2014 by SAGE Publications.International evidence demonstrates the importance of engaging parents in the education of their ‘high-potential’ children, yet limited research has focused on the involvement of parents from differing economic strata/backgrounds. The current study explored the dilemmas of parenting academically high-ability children from economically deprived urban areas in the UK. Data were gathered from a sample of parents whose children attended a university-based sustained intervention programme for designated ‘gifted’ pupils aged 12–16. Parental perceptions were sought in relation to (a) the usefulness/impact of the intervention programme, (b) parents’ aspirations for their children growing up in economically deprived urban areas and (c) parents’ views on the support provided by the extended family, peer groups and the wider community. The findings have significant implications for both policy and practice and, more specifically, for engaging parents in intervention programmes offered by universities and schools to children in order to increase their access to higher education and for enhancing their life chances