50 research outputs found
Pion mass dependence of the nucleon mass in the chiral quark soliton model
The dependence of the nucleon mass on the mass of the pion is studied in the
framework of the chiral quark-soliton model. A remarkable agreement is observed
with lattice data from recent full dynamical simulations. The possibility and
limitations to use the model results as a guideline for the chiral
extrapolation of lattice data are discussed.Comment: 14 pages, 12 figures, 4 tables. v2: References added, new figure
included, discussion improved, typos fixed, matches published versio
The pion mass dependence of the nucleon form-factors of the energy momentum tensor in the chiral quark-soliton model
The nucleon form factors of the energy-momentum tensor are studied in the
large-Nc limit in the framework of the chiral quark-soliton model for model
parameters that simulate physical situations in which pions are heavy. This
allows for a direct comparison to lattice QCD results.Comment: 17 pages, 12 figure
The target asymmetry in hard vector-meson electroproduction and parton angular momenta
The target asymmetry for electroproduction of vector mesons is investigated
within the handbag approach. While the generalized parton distribution (GPD) H
is taken from a previous analysis of the elctroproduction cross section, we
here construct the GPD E from double distributions and constrain it by the
Pauli form factors of the nucleon, positivity bounds and sum rules. Predictions
for the target asymmetry are given for various vector mesons and discussed how
experimental data on the asymmetry will further constrain E and what we may
learn about the angular momenta the partons carry.Comment: 24 pages, 11 figures, late
The nucleon form-factors of the energy momentum tensor in the Skyrme model
The nucleon form factors of the energy-momentum tensor are studied in the
large-Nc limit in the framework of the Skyrme model.Comment: 19 pages, 11 Figures, 2 Tables; correction in footnote 2, extension
in App.D, some reformulations, references added, results and conclusions
unchange
The role of orbital angular momentum in the proton spin
The orbital angular momenta and of up and down quarks in the
proton are estimated as functions of the energy scale as model-independently as
possible, on the basis of Ji's angular momentum sum rule. This analysis
indicates that is large and negative even at low energy scale of
nonperturbative QCD, in contrast to Thomas' similar analysis based on the
refined cloudy bag model. We pursuit the origin of this apparent discrepancy
and suggest that it may have a connection with the fundamental question of how
to define quark orbital angular momenta in QCD.Comment: 14 pages, 3 figures, 1 table A slightly extended version to appear in
Eur. Phys. J.
Analysis of traumatic injuries presenting to a referral hospital emergency department in Moshi,
Abstract Background: Injuries represent a significant and growing public health concern in the developing world, yet their impact on patients and the emergency health-care system in the countries of East Africa has received limited attention. This study evaluates the magnitude and scope of injury related disorders in the population presenting to a referral hospital emergency department in northern Tanzania
Unified framework for generalized and transverse-momentum dependent parton distributions within a 3Q light-cone picture of the nucleon
We present a systematic study of generalized transverse-momentum dependent
parton distributions (GTMDs). By taking specific limits or projections, these
GTMDs yield various transverse-momentum dependent and generalized parton
distributions, thus providing a unified framework to simultaneously model
different observables. We present such simultaneous modeling by considering a
light-cone wave function overlap representation of the GTMDs. We construct the
different quark-quark correlation functions from the 3-quark Fock components
within both the light-front constituent quark model as well as within the
chiral quark-soliton model. We provide a comparison with available data and
make predictions for different observables.Comment: version to appear in JHE
Does methylphenidate improve inhibition and other cognitive abilities in adults with childhood-onset ADHD?
Contains fulltext :
48908.pdf (publisher's version ) (Closed access)We examined the effect of methylphenidate (Mph) on inhibition and several other cognitive abilities in 43 adults with Attention Deficit Hyperactivity Disorder (ADHD) by use of Conners' Continuous Performance Test (CPT) and the Change Task (ChT), an extension of the Stop Signal Test (SST). In a double blind, cross-over, placebo controlled study with Mph, tests were administered during the third week of individually titrated treatment with Mph (maximum dose 1 mg / kg / day) and during the third week of treatment with placebo. We established large medication effects for commission errors, standard error of mean reaction time, and attentiveness on the CPT, as well as moderate medication effects for mean reaction time on the CPT and response re-engagement speed on the ChT. For Stop Signal Reaction Time (SSRT) on the ChT, we also established large effects of Mph, but only in a group of participants who showed slow SSRTs on placebo. Mph indeed ameliorates inhibition, which is the core problem of ADHD, and certain other cognitive abilities in adults with ADHD