947 research outputs found

    More Than a Test Score: Toward a More Balanced School Accountability System

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    Using a zone of mediation framework, we explore how one school district designed a community-based accountability system (CBAS) reflecting community stakeholders’ values, priorities, and goals. We collected rich data sets from a document analysis, focus group, and individual interviews. Our findings indicated a strong dissatisfaction with test-based accountability that led the district to engage its stakeholders in designing a CBAS using multiple achievement measures to report on district success. The importance of collaboration with other districts and leaders at the local, regional, and state levels also emerged. This study highlights the importance of stakeholder involvement, leadership, and collaboration when making equity-minded reforms and exemplifies how to engage in this work

    Relativistic effects in the processes of heavy quark fragmentation

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    In the framework based on the quasipotential method and relativistic quark model a new covariant expression for the heavy quark fragmentation amplitude to fragment into the pseudoscalar and vector S-wave heavy mesons is obtained. It contains all possible relativistic corrections including the terms connected with the transformation law of the bound state wave function to the reference frame of the moving meson. Relativistic corrections of order {\bf p}^2/m^2 to the heavy quark fragmentation distributions into (\bar c c), (\bar b c) and (\bar b b) states are calculated as functions of the longitudinal momentum fraction z and the transverse momentum p_T relative to the jet axis.Comment: 23 pages, 6 figure

    Axial anomaly: the modern status

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    The modern status of the problem of axial anomaly in QED and QCD is reviewed. Two methods of the derivation of the axial anomaly are presented: 1) by splitting of coordinates in the expression for the axial current and 2) by calculation of triangle diagrams, where the anomaly arises from the surface terms in momentum space. It is demonstrated, that the equivalent formulation of the anomaly can be given, as a sum rule for the structure function in dispersion representation of three point function of AVV interaction. It is argued, that such integral representation of the anomaly has some advantages in the case of description of the anomaly by contribution of hadronic states in QCD. The validity of the t'Hooft consistency condition is discussed. Few examples of the physical application of the axial anomaly are given.Comment: 17 pages, 3 figures, to be published in International Journal of Modern Physics A, few minor correction were done, two references were adde

    Double-Spin Transverse Asymmetries in Drell-Yan Processes

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    We calculate the double-spin transverse asymmetries for the Drell-Yan lepton pair production in p-p and p-anti p collisions. We assume the transverse and the longitudinal polarization densities to be equal at a very small scale, as it is suggested by confinement model results. Using a global fit for the longitudinal distributions, we find transverse asymmetries of order of 10^-2 at most, in the accessible kinematic regions.Comment: 8 pages, REVTeX, 6 figures included as file figures.tar.g

    Models for the Polarized Parton Distributions of the Nucleon

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    Polarized deep inelastic scattering (DIS) data are analyzed in leading and next-to-leading order of QCD within the common `standard' scenario of polarized parton distributions with a flavor-symmetric light sea (antiquark) distribution δqˉ\delta\bar{q}, and a completely SU(3)f_f broken `valence' scenario with totally flavor-asymmetric light sea densities (δuˉδdˉδsˉ)(\delta\bar{u}\neq\delta\bar{d}\neq\delta\bar{s}). The latter flavor-broken light sea distributions are modelled with the help of a Pauli-blocking ansatz at the low radiative/dynamical input scales of μLO(NLO)2=0.26\mu_{\rm LO(NLO)}^2=0.26 (0.40) GeV2^2 which complies with predictions of the chiral quark-soliton model and expectations based on the statistical parton model as well as with the corresponding, well established, flavor-broken unpolarized sea (dˉ>uˉ\bar{d}>\bar{u}). Present semi-inclusive DIS data cannot yet uniquely discriminate between those two flavor-symmetric and flavor-broken polarized light sea scenarios.Comment: 39 pages, LaTe

    Single spin asymmetries in DIS

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    We consider possible mechanisms for single spin asymmetries in inclusive Deep Inelastic Scattering (DIS) processes with unpolarized leptons and transversely polarized nucleons. Tests for the effects of non-zero \bfk_\perp, for the properties of spin dependent quark fragmentations and for quark helicity conservation are suggested.Comment: 5 pages, LaTeX, no figures. Revised version, to be published in Phys. Rev. D. Some equations and statements added to clarify text and notation

    New anomalous trajectory in Regge theory

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    We show that a new Regge trajectory with \alpha_{f_1} (0) \approx 1 and slope \alpha_{f_1}'(0) \approx 0 explains the features of hadron-hadron scattering and photoproduction of the rho and phi mesons at large energy and momentum transfer. This trajectory with quantum numbers P = C = +1 and odd signature can be considered as a natural partner of the Pomeron which has even signature. The odd signature of the new exchange leads to contributions to the spin-dependent cross sections, which do not vanish at large energy. The links between the anomalous properties of this trajectory, the axial anomaly and the flavor singlet axial vector f_1 (1285) meson are discussed.Comment: 20 pages, REVTeX, 8 figures (9 eps files), version to appear in Phys. Rev.

    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.

    Gauge Is More Than Mathematical Redundancy

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    Physical systems may couple to other systems through variables that are not gauge invariant. When we split a gauge system into two subsystems, the gauge-invariant variables of the two subsystems have less information than the gauge-invariant variables of the original system; the missing information regards degrees of freedom that express relations between the subsystems. All this shows that gauge invariance is a formalization of the relational nature of physical degrees of freedom. The recent developments on boundary variables and boundary charges are clarified by this observation
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