2,389 research outputs found
Strangeness contribution to the vector and axial form factors of the nucleon
The strangeness contribution to the vector and axial form factors of the
nucleon is presented for momentum transfers in the range
GeV. The results are obtained via a combined analysis of forward-scattering
parity-violating elastic asymmetry data from the and HAPPEx
experiments at Jefferson Lab, and elastic and scattering
data from Experiment 734 at Brookhaven National Laboratory. The
parity-violating asymmetries measured in elastic scattering at
forward angles establish a relationship between the strange vector form factors
and , with little sensitivity to the strange axial form factor
. On the other hand, elastic neutrino scattering at low is
dominated by the axial form factor, with still some significant sensitivity to
the vector form factors as well. The combination of the two data sets allows
the simultaneous extraction of , , and over a significant
range of for the very first time.Comment: 3 pages, 1 figure, will appear in AIP Conference Proceedings for
PANIC 200
Strange form factors of the nucleon in a two-component model
The strange form factors of the nucleon are studied in a two-component model
consisting of a three-quark intrinsic structure surrounded by a meson cloud. A
comparison with the available experimental world data from the SAMPLE, PVA4,
HAPPEX and G0 collaborations shows a good overall agreement. The strange
magnetic moment is found to be positive, 0.315 nm.Comment: 11 pages, 2 tables, 5 figures, accepted for publication in J. Phys.
G. Revised version, new figures, extra table, new results, updated reference
Personalised Focus-Metaphor Interfaces: An Eye Tracking Study on User Confusion
Personalised web interfaces are expected to improve user interaction with web content. But since the delivery of personalised web content is currently not reliable, a key question is how much users may be confused and slowed down when personalised delivery goes wrong. The aim of the study reported in this paper was to investigate a worst-case scenario of failed personalised content presentation â a dynamic presentation of content where content was dynamically presented, but content units were selected at random. We employed eye-tracking to monitor the differences in usersâ attention and navigation when interacting with this âdysfunctionalâ dynamic interface, and a static version. We found that subjects who interacted with the dysfunctional version took 10% longer to read their material than those with static content, and displayed a different strategy in scanning the interface. The relatively small difference in navigation time in first-time viewers of dynamically presented content, and of the results from the eye-tracking patterns, suggests that users are not significantly confused and slowed down by dynamic presentation of content when using a Focus-Metaphor interfac
Signals for strange quark contributions to the neutrino (antineutrino) scattering in quasi-elastic region
Strange quark contributions to the neutrino (antineutrino) scattering are
investigated on the elastic neutrino-nucleon scattering and the
neutrino-nucleus scattering for 12C target in the quasi-elastic region on the
incident energy of 500 MeV, within the framework of a relativistic single
particle model. For the neutrino-nucleus scattering, the effects of final state
interaction for the knocked-out nucleon are included by a relativistic optical
potential. In the cross sections we found some cancellations of the strange
quark contributions between the knocked-out protons and neutrons. Consequently,
the asymmetries between the incident neutrino and antineutrino which is the
ratio of neutral current to charged current, and the difference between the
asymmetries are shown to be able to yield more feasible quantities for the
strangeness effects. In order to explicitly display importance of the
cancellations, results of the exclusive reaction 16O(\nu, \nu' p) are
additionally presented for detecting the strangeness effects.Comment: 14 pages, 8 figures, submitted to Phys. Lett.
Children\u27s Understanding of the Concept of Physical Activity
This study evaluated 4th-grade students\u27 understanding of the concept of physical activity and assessed the effects of two interventions to enhance the students\u27 understanding of this concept. Students were randomly assigned to 1 of 3 conditions: the video group (n=40) watched a 5-min video describing physical activity; the verbal group (n=42) listened to a generic description of physical activity; the control group received no instruction (n=45). Students completed a 17-item checklist testing their understanding of the concept of physical activity. Compared to controls, students in the verbal and video group demonstrated significantly higher checklist scores, with the video group scoring significantly higher than the verbal group. Only 35.6% of the controls compared to 52.4% and 70.0% of the verbal and video group respectively, could classify \u3e 15 of the checklist items correctly. The results indicate that, without intervention, children have a limited understanding of the concept of physical activity
Tracking of Physical Activity, Physical Inactivity, and Health-Related Physical Fitness in Rural Youth
This study examined the tracking of selected measures of physical activity, inactivity, and fitness in a cohort of rural youth. Students (N=181, 54.7% female, 63.5% African American) completed test batteries during their fifth- (age=10.7±0.7 years), sixth-, and seventh-grade years. The Previous Day Physical Activity Recall (PDPAR) was used to assess 30-min blocks of vigorous physical activity (VPA), moderate-to-vigorous physical activity (MVPA), TV watching and other sedentary activities, and estimated energy expenditure (EE). Fitness measures included the PWC 170 cycle ergometer test, strength tests, triceps skinfold thickness, and BMI. Intraclass correlation coefficients (ICCs) for VPA, MVPA, and after-school EE ranged from 0.63 to 0.78. ICCs ranged from 0.49 to 0.71 for measures of inactivity and from 0.78 to 0.82 for the fitness measures. These results indicate that measures of physical activity, inactivity, and physical fitness tend to track during the transition from elementary to middle school
Renaissance of the ~1 TeV Fixed-Target Program
This document describes the physics potential of a new fixed-target program
based on a ~1 TeV proton source. Two proton sources are potentially available
in the future: the existing Tevatron at Fermilab, which can provide 800 GeV
protons for fixed-target physics, and a possible upgrade to the SPS at CERN,
called SPS+, which would produce 1 TeV protons on target. In this paper we use
an example Tevatron fixed-target program to illustrate the high discovery
potential possible in the charm and neutrino sectors. We highlight examples
which are either unique to the program or difficult to accomplish at other
venues.Comment: 31 pages, 11 figure
Pionic Atoms as Compound States in Nucleon-Nucleus Collisons: Status Report on the Cooler Experiment CE02
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
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