1,292 research outputs found
New relation between transverse angular momentum and generalized parton distributions
I derive a rigorous relation between the expectation value of the transverse
component of the angular momentum of a quark in a transversely polarized
nucleon in terms of the Generalized Parton Distributions H and E, namely
= 1/2M [P_0 \int dx x E_q(x,0,0) + M \int dx x H_q(x,0,0)] where
P_0 is the energy of the nucleon and where "quark" implies the sum of quark and
antiquark of a given flavor. A similar relation holds for gluons. The result is
remarkably similar to Ji's relation for the case of longitudinal polarization.
In this revised version, I have rectified some misleading statements,
introduced a more precise notation and specified mpre clearly the meaning of
the terms in both the Ji and the new tranverse relation.Comment: 6 page
More Than a Test Score: Toward a More Balanced School Accountability System
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
September 10, 1998
The Breeze is the student newspaper of James Madison University in Harrisonburg, Virginia
An absolute polarimeter for high energy protons
A study of the spin asymmetries for polarized elastic proton proton
collisions in the electromagnetic hadronic interference (CNI) region of
momentum transfer provides a method of self calibration of proton polarization.
The method can be extended to non-identical spin half scattering so that, in
principle, the polarization of a proton may be obtained through an analysis of
its elastic collision with a different polarized particle, helium 3 for
instance. Sufficiently large CNI spin asymmetries provide enough information to
facilitate the evaluation of nearly all the helicity amplitudes at small t as
well as the polarization of both initial spin half fermions. Thus it can serve
equally well as a polarimeter for helium 3
Relativistic effects in the processes of heavy quark fragmentation
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
Double-Spin Transverse Asymmetries in Drell-Yan Processes
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
POWER UP: A Persuasive Writing Strategy for Secondary Students with Emotional and Behavioral Disorders
In the area of written expression, students with emotional and behavioral disorders (EBD) typically perform one to two grades below their same age, non-disabled peers. Unfortunately, there is a lack of research on writing interventions to improve these outcomes. The purpose of this study was to examine the effect of a persuasive writing strategy called POWER UP to improve the quality of persuasive essays for secondary students with EBD. The results suggest that a mnemonic strategy based on the Self-Regulated Strategy Development Model (SRSD) can improve the quality of persuasive writing essays for secondary students with EBD
Hard exclusive electroproduction of decuplet baryons in the large N_c limit
The cross sections and transverse spin asymmetries in the hard exclusive
electroproduction of decuplet baryons are calculated in the large N_c limit and
found to be comparable to that of octet baryons. Large N_c selection rules for
the production amplitudes are derived, leading to new sensitive tests of the
spin aspects of the QCD chiral dynamics both in the nonstrange and strange
sectors. Importance of such studies for the reliable extraction of the pion
form factor from pion electroproduction is explained.Comment: 4 pages, 3 figure
Nuclear Antishadowing in Neutrino Deep Inelastic Scattering
The shadowing and antishadowing of nuclear structure functions in the
Gribov-Glauber picture is due respectively to the destructive and constructive
interference of amplitudes arising from the multiple-scattering of quarks in
the nucleus. The effective quark-nucleon scattering amplitude includes Pomeron
and Odderon contributions from multi-gluon exchange as well as Reggeon
quark-exchange contributions. We show that the coherence of these
multiscattering nuclear processes leads to shadowing and antishadowing of the
electromagnetic nuclear structure functions in agreement with measurements.
This picture leads to substantially different antishadowing for charged and
neutral current reactions, thus affecting the extraction of the weak-mixing
angle . We find that part of the anomalous NuTeV result for
could be due to the nonuniversality of nuclear antishadowing for
charged and neutral currents. Detailed measurements of the nuclear dependence
of individual quark structure functions are thus needed to establish the
distinctive phenomenology of shadowing and antishadowing and to make the NuTeV
results definitive.Comment: 38 pages, 15 figure
- …