1,232 research outputs found

    The Educational Adjustment Program Profile: A Queensland Initiative in the identification and Monitoring of Students with a Disability

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    The effective identification and monitoring of students with a disability is a complex and important aspect of educational service delivery for students with a disability in Queensland. Building on previous initiatives in this domain Education Queensland has piloted the development of the Educational Adjustment Program (EAP) profile. Based on the data from the initial survey sample of more than 1500 school age students with a disability across Queensland, this paper highlights: the design of the Education Adjustment Program Adjustment Profile (EAP); some of its psychometric properties; gender and Indigenous student dimensions within the data; and how the EAP instrument compares with the 1 to 6 ascertainment rating scale

    The role of Cahn and Sivers effects in Deep Inelastic Scattering

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    The role of intrinsic \bfk_\perp in inclusive and semi-inclusive Deep Inelastic Scattering processes (phX\ell p \to \ell h X) is studied with exact kinematics within QCD parton model at leading order; the dependence of the unpolarized cross section on the azimuthal angle between the leptonic and the hadron production planes (Cahn effect) is compared with data and used to estimate the average values of kk_\perp both in quark distribution and fragmentation functions. The resulting picture is applied to the description of the weighted single spin asymmetry AUTsin(ϕπϕS)A_{UT}^{\sin(\phi_\pi - \phi_S)} recently measured by the HERMES collaboration at DESY; this allows to extract some simple models for the quark Sivers functions. These are compared with the Sivers functions which succeed in describing the data on transverse single spin asymmetries in \pup p \to \pi X processes; the two sets of functions are not inconsistent. The extracted Sivers functions give predictions for the COMPASS measurement of AUTsin(ϕπϕS)A_{UT}^{\sin(\phi_\pi - \phi_S)} in agreement with recent preliminary data, while their contribution to HERMES AULsinϕπA_{UL}^{\sin\phi_\pi} is computed and found to be small. Predictions for AUTsin(ϕKϕS)A_{UT}^{\sin(\phi_K - \phi_S)} for kaon production at HERMES are also given.Comment: 21 pages, 12 figures, revtex, version published in PRD, one figure, comments and references adde

    Extracting the Proton ubar content from pp->Direct Photon plus Jet Cross Sections

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    An analysis procedure is proposed to measure the antiquark distributions in the proton over the region 0.01 < x < 0.1. The procedure involves the measurement of high p_t asymmetric direct photon and jet final states in pp interactions. This measurement can be made at the RHIC collider running in pp mode at an energy of sqrt(s)=500 GeV/c. This analysis identifies a region of phase space where the contribution from quark-antiquark annihilation uncharacteristically approaches the magnitude of the contribution from the leading process, quark-gluon Compton scattering. The forward-backward angular asymmetry in the parton center of mass is sensitive to the antiquark content of the proton and the ubar parton density function can be extracted.Comment: 21 pages, 7 figure

    Gamma ray astronomy and baryonic dark matter

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    Recently, Dixon et al. have re-analyzed the EGRET data, finding a statistically significant diffuse γ\gamma-ray emission from the galactic halo. We show that this emission can naturally be explained within a previously-proposed model for baryonic dark matter, in which γ\gamma-rays are produced through the interaction of high-energy cosmic-ray protons with cold H2H_2 clouds clumped into dark clusters - these dark clusters supposedly populate the outer galactic halo and can show up in microlensing observations. Our estimate for the halo γ\gamma-ray flux turns out to be in remarkably good agreement with the discovery by Dixon et al. We also address future prospects to test our predictions.Comment: 9 pages, 1 figure included, to appear in ApJ 510, L103 (1999

    Leading Chiral Contributions to the Spin Structure of the Proton

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    The leading chiral contributions to the quark and gluon components of the proton spin are calculated using heavy-baryon chiral perturbation theory. Similar calculations are done for the moments of the generalized parton distributions relevant to the quark and gluon angular momentum densities. These results provide useful insight about the role of pions in the spin structure of the nucleon, and can serve as a guidance for extrapolating lattice QCD calculations at large quark masses to the chiral limit.Comment: 8 pages, 2 figures; a typo in Ref. 7 correcte

    A Self-Consistent Approach to Neutral-Current Processes in Supernova Cores

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    The problem of neutral-current processes (neutrino scattering, pair emission, pair absorption, axion emission, \etc) in a nuclear medium can be separated into an expression representing the phase space of the weakly interacting probe, and a set of dynamic structure functions of the medium. For a non-relativistic medium we reduce the description to two structure functions S_A(\o) and S_V(\o) of the energy transfer, representing the axial-vector and vector interactions. SVS_V is well determined by the single-nucleon approximation while SAS_A may be dominated by multiply interacting nucleons. Unless the shape of S_A(\o) changes dramatically at high densities, scattering processes always dominate over pair processes for neutrino transport or the emission of right-handed states. Because the emission of right-handed neutrinos and axions is controlled by the same medium response functions, a consistent constraint on their properties from consideration of supernova cooling should use the same structure functions for both neutrino transport and exotic cooling mechanisms.Comment: 33 pages, Te

    Gluon Fusion: A Probe of Higgs Sector CP Violation

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    We demonstrate that CP violation in the Higgs sector, \eg\ of a multi-doublet model, can be directly probed using gluon-gluon collisions at the SSC. % requires phyzzx.tex macro packageComment: UCD-93-

    Globular cluster formation within the Aquarius simulation

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    The Aquarius project is a very high-resolution simulation capable of resolving the full mass range of potential globular cluster (GC) formation sites. With a particle mass mp= 1.4 × 104 M¿, Aquarius yields more than 100 million particles within the virial radius of the central halo which has a mass of 1.8 × 1012 M¿, similar to that of the Milky Way. With this particle mass, dark matter concentrations (haloes) that give rise to GCs via our formation criteria contain a minimum of ~2000 particles. Here, we use this simulation to test a model of metal-poor GC formation based on collapse physics. In our model, GCs form when the virial temperatures of haloes first exceed 104 K as this is when electronic transitions allow the gas to cool efficiently. We calculate the ionizing flux from the stars in these first clusters and stop the formation of new clusters when all the baryonic gas of the Galaxy is ionized. This is achieved by adopting reasonable values for the star formation efficiencies and escape fraction of ionizing photons which result in similar numbers and masses of clusters to those found in the Milky Way. The model is successful in that it predicts ages (peak age ~13.3 Gyr) and a spatial distribution of metal-poor GCs which are consistent with the observed populations in the Milky Way. The model also predicts that less than 5 per cent of GCs within a radius of 100 kpc have a surviving dark matter halo, but the more distant clusters are all found in dark matter concentrations. We then test a scenario of metal-rich cluster formation by examining mergers that trigger star formation within central gas discs. This results in younger (~7¿13.3 Gyr), more centrally located clusters (40 metal-rich GCs within 18 kpc from the centre of the host) which are consistent with the Galactic metal-rich population. We test an alternate model in which metal-rich GCs form in dwarf galaxies that become stripped as they merge with the main halo. This process is inconsistent with observed metal-rich globulars in the Milky Way because it predicts spatial distributions that are far too extended

    Scheme Independence of g1p(x,Q2)g_1^p (x, Q^2)

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    We work with two general factorization schemes in order to explore the consequences of imposing scheme independence on g1p(x,Q2)g_1^p (x, Q^2). We see that although the light quark sector is indifferent to the choice of a particular scheme, the extension of the calculations to the heavy quark sector indicates that a scheme like the MSˉ\bar{MS} is preferable.Comment: 11 pages, 2 figures. To appear in the Brief Reports of Phys. Rev.

    Sea Contributions and Nucleon Structure

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    We suggest a general formalism to treat a baryon as a composite system of three quarks and a `sea'. In this formalism, the sea is a cluster which can consists of gluons and quark-antiquark pairs. The hadron wave function with a sea component is given. The magnetic moments, related sum rules and axial weak coupling constants are obtained. The data seems to favor a vector sea rather than a scalar sea. The quark spin distributions in the nucleon are also discussed.Comment: 24 page
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