254 research outputs found
Production of Jet Pairs at Large Relative Rapidity in Hadron-Hadron Collisions as a Probe of the Perturbative Pomeron
The production of jet pairs with small transverse momentum and large relative
rapidity in high energy hadron-hadron collisions is studied. The rise of the
parton-level cross section with increasing rapidity gap is a fundamental
prediction of the BFKL `perturbative pomeron' equation of Quantum
Chromodynamics. However, at fixed collider energy it is difficult to
disentangle this effect from variations in the cross section due to the parton
distributions. It is proposed to study instead the distribution in the
azimuthal angle difference of the jets as a function of the rapidity gap. The
flattening of this distribution with increasing dijet rapidity gap is shown to
be a characteristic feature of the BFKL behaviour. Predictions for the Fermilab
proton-antiproton collider are presented.Comment: 17 pages, 11 figures, preprint DTP/94/0
dGEMRIC as a tool for measuring changes in cartilage quality following high tibial osteotomy:A feasibility study
SummaryObjectiveThe high tibial osteotomy (HTO) is an effective strategy for treatment of painful medial compartment knee osteoarthritis. Effects on cartilage quality are largely unknown. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) enables non-invasive assessment of cartilage glycosaminoglycan content. This study aimed to evaluate if dGEMRIC could detect relevant changes in cartilage glycosaminoglycan content following HTO.DesignTen patients with medial compartment osteoarthritis underwent a dGEMRIC scan prior to HTO, and after bone healing and subsequent hardware removal. A dGEMRIC index (T1Gd) was used for changes in cartilage glycosaminoglycan content, a high T1Gd indicating a high glycosaminoglycan content and vice versa. Radiographic analysis included mechanical axis and tibial slope measurement. Clinical scores [Knee Osteoarthritis Outcome Scale (KOOS), visual analogue score (VAS) for pain, Knee Society Clinical Rating System (KSCRS)] before, 3 and 6 months after HTO and after hardware removal were correlated to T1Gd changes.ResultsOverall a trend towards a decreased T1Gd, despite HTO, was observed. Before and after HTO, lateral femoral condyle T1Gd was higher than medial femoral condyle (MFC) T1Gd and tibial cartilage T1Gd was higher than that of femoral cartilage (PÂ <Â 0.001). The MFC had the lowest T1Gd before and after HTO. Clinical scores all improved significantly (PÂ <Â 0.01), KOOS Symptoms and QOL were moderately related to changes in MFC T1Gd.ConclusionsdGEMRIC effectively detected differences in cartilage quality within knee compartments before and after HTO, but no changes due to HTO were detected. Hardware removal post-HTO seems essential for adequate T1Gd interpretation. T1Gd was correlated to improved clinical scores on a subscore level only. Longer follow-up after HTO may reveal lasting changes.ClinicalTrials.gov registration ID: NCT01269944
Multiorder coherent Raman scattering of a quantum probe field
We study the multiorder coherent Raman scattering of a quantum probe field in
a far-off-resonance medium with a prepared coherence. Under the conditions of
negligible dispersion and limited bandwidth, we derive a Bessel-function
solution for the sideband field operators. We analytically and numerically
calculate various quantum statistical characteristics of the sideband fields.
We show that the multiorder coherent Raman process can replicate the
statistical properties of a single-mode quantum probe field into a broad comb
of generated Raman sidebands. We also study the mixing and modulation of photon
statistical properties in the case of two-mode input. We show that the prepared
Raman coherence and the medium length can be used as control parameters to
switch a sideband field from one type of photon statistics to another type, or
from a non-squeezed state to a squeezed state and vice versa.Comment: 12 pages, 7 figures, to be published in Phys. Rev.
Jet-jet and hadron-jet correlations in hadro- and electro-production
We discuss, in the framework of perturbative QCD at next to leading order,
two related observables which are usually considered to provide tests of the
BFKL dynamics : jet-jet correlations at Tevatron energies and forward
particle-jet correlations at HERA. In the first case we study the rapidity gap
dependence of the azimuthal correlations and find slightly too strong
correlations at large gap. In the second case we discuss the cross section as
well as the azimuthal correlations over a rapidity gap range of 5 units. We
find that the requirement of a forward particle imposes strong kinematical
constraints which distort the distributions, notably at small rapidity gaps. We
also show that the decorrelation is stronger in electroproduction than in
hadron-hadron collisions. Unfortunately no data are yet available for
comparison.Comment: LaTeX, 19 pages, 7 figures (9 figure files
A Search for Selectrons and Squarks at HERA
Data from electron-proton collisions at a center-of-mass energy of 300 GeV
are used for a search for selectrons and squarks within the framework of the
minimal supersymmetric model. The decays of selectrons and squarks into the
lightest supersymmetric particle lead to final states with an electron and
hadrons accompanied by large missing energy and transverse momentum. No signal
is found and new bounds on the existence of these particles are derived. At 95%
confidence level the excluded region extends to 65 GeV for selectron and squark
masses, and to 40 GeV for the mass of the lightest supersymmetric particle.Comment: 13 pages, latex, 6 Figure
E-retailing ethics in Egypt and its effect on customer repurchase intention
The theoretical understanding of online shopping behaviour has received much attention. Less focus has been given to the formation of the ethical issues that result from online shopper interactions with e-retailers. The vast majority of earlier research on this area is conceptual in nature and limited in scope by focusing on consumersâ privacy issues. Therefore, the purpose of this paper is to propose a theoretical model explaining what factors contribute to online retailing ethics and its effect on customer repurchase intention. The data were analysed using variance-based structural equation modelling, employing partial least squares regression. Findings indicate that the five factors of the online retailing ethics (security, privacy, non- deception, fulfilment/reliability, and corporate social responsibility) are strongly predictive of online consumersâ repurchase intention. The results offer important implications for e-retailers and are likely to stimulate further research in the area of e-ethics from the consumersâ perspective
Gluons and the quark sea at high energies: distributions, polarization, tomography
This report is based on a ten-week program on "Gluons and the quark sea at
high-energies", which took place at the Institute for Nuclear Theory in Seattle
in Fall 2010. The principal aim of the program was to develop and sharpen the
science case for an Electron-Ion Collider (EIC), a facility that will be able
to collide electrons and positrons with polarized protons and with light to
heavy nuclei at high energies, offering unprecedented possibilities for
in-depth studies of quantum chromodynamics. This report is organized around
four major themes: i) the spin and flavor structure of the proton, ii)
three-dimensional structure of nucleons and nuclei in momentum and
configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and
the search for physics beyond the Standard Model. Beginning with an executive
summary, the report contains tables of key measurements, chapter overviews for
each of the major scientific themes, and detailed individual contributions on
various aspects of the scientific opportunities presented by an EIC.Comment: 547 pages, A report on the joint BNL/INT/Jlab program on the science
case for an Electron-Ion Collider, September 13 to November 19, 2010,
Institute for Nuclear Theory, Seattle; v2 with minor changes, matches printed
versio
Multiplicity dependence of inclusive J/psi production at midrapidity in pp collisions at root s=13 TeV
Measurements of the inclusive J/psi yield as a function of charged-particle pseudorapidity density dN(ch)/d eta in pp collisions at root s = 13 TeV with ALICE at the LHC are reported. The J/psi meson yield is measured at midrapidity (vertical bar y vertical bar <0.9) in the dielectron channel, for events selected based on the charged-particle multiplicity at midrapidity (vertical bar eta vertical bar <1) and at forward rapidity (-3.7 <eta <-1.7 and 2.8 <eta <5.1); both observables are normalized to their corresponding averages in minimum bias events. The increase of the normalized J/psi yield with normalized dN(ch)/d eta is significantly stronger than linear and dependent on the transverse momentum. The data are compared to theoretical predictions, which describe the observed trends well, albeit not always quantitatively. (C) 2020 European Organization for Nuclear Research. Published by Elsevier B.V.Peer reviewe
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