190 research outputs found
Pentaquark baryon production at the Relativistic Heavy Ion Collider
Production of pentaquark baryons in central relativistic heavy ion
collisions is studied in a kinetic model. Assuming that a quark-gluon plasma is
produced in the collisions, we first determine the number of
produced from the quark-gluon plasma using a parton coalescence model, and then
take into consideration its production and absorption in subsequent hadronic
matter via the reactions ,
, and \piN\leftrightarrow\bar K\Theta. We find
that although the final number is affected by hadronic interactions,
it remains sensitive to the initial number of produced from the
quark-gluon plasma, particularly in the case of a small width as
imposed by the and scattering data. Because of small baryon
chemical potential in the hot dense matter produced in these collisions, the
number of produced anti- is only slightly smaller than that of
.Comment: 6 pages, 2 figures, revised version, to appear in PL
Single Electron Elliptic Flow Measurements in Au+Au Collisions from STAR
Recent measurements of elliptic flow (v_2) and the nuclear modification
factor (R_{CP}) of strange mesons and baryons in the intermediate p_T domain in
Au+Au collisions demonstrate a scaling with the number of constituent-quarks.
This suggests hadron production via quark coalescence from a thermalized parton
system. Measuring the elliptic flow of charmed hadrons, which are believed to
originate rather from fragmentation than from coalescence processes, might
therefore change our view of hadron production in heavy ion collisions.
While direct v_2 measurements of charmed hadrons are currently not available,
single electron v_2 at sufficiently high transverse momenta can serve as a
substitute. At transverse momenta above 2 GeV/c, the production of single
electrons from non-photonic sources is expected to be dominated by the decay of
charmed hadrons. Simulations show a strong correlation between the flow of the
charmed hadrons and the flow of their decay electrons for p_T > 2 GeV/c.
We will present preliminary STAR results from our single electron v_2
measurements from Au+Au collisions at RHIC energies.Comment: 10 pages, 7 figures Proceedings of the Hot Quarks 2004 Conference,
July 18-24 2004, Taos Valley, New Mexico, USA to be published in Journal of
Physics
Recombination Models
We review the current status of recombination and coalescence models that
have been successfully applied to describe hadronization in heavy ion
collisions at RHIC energies. Basic concepts as well as actual implementations
of the idea are discussed. We try to evaluate where we stand in our
understanding at the moment and what remains to be done in the future.Comment: Plenary Talk at Quark Matter 2004, submitted to J. Phys. G, 8 pages,
3 figure
Directed and Elliptic Flow at RHIC
We present the directed flow measurement () from Au+Au collisions at
\sqrtsNN = 62 GeV. Over the pseudorapidity range we have studied, which
covers from -1.2 to 1.2 and , the magnitude of
for charged particles is found to increase monotonously with pseudorapidity for
all centralities. No `` wiggle'', as predicted by various theoretical
models, is observed at midrapidity. Elliptic flow () from moderate high
particles () at \sqrtsNN = 200 GeV is presented as a
function of impact parameter. It is found that models that are based on {\it
jet quenching} alone appear to underpredict at moderate high , while
the model that incorporates both, recombination and fragmentation, describes
the data better.Comment: 6 pages, 4 figures. Proceeding for Hot Quark 04 conference Changes in
the revision are mostly English fixes. v1 versus eta plot is flipped over to
follow the conventio
Sources of scientific creativity: participant observation of a public research institute in Korea
Dynamic capabilities and knowledge management: an integrative role for learning?
Modern strategic management theories try to explain why firms differ, because new sources of competitive advantage are keenly sought in the dynamic and complex environment of global competition. Two areas in particular have attracted the attention of researchers: the role of dynamic capabilities, and the firm's abilities for knowledge management. In this paper, we argue that there is a link between these two concepts, which has not been fully articulated in the literature. The aim of the paper is therefore to ascertain the conceptual connection between them as a basis for future research. Our proposed framework acknowledges and critiques the distinct roots of each field, identifies boundaries, and proposes relationships between the constructs and firm performance
Charmed Exotics in Heavy Ion Collisions
Based on the color-spin interaction in diquarks, we argue that charmed
multiquark hadrons are likely to exist. Because of the appreciable number of
charm quarks produced in central nucleus-nucleus collisions at
ultrarelativistic energies, production of charmed multiquark hadrons is
expected to be enhanced in these collisions. Using both the quark coalescence
model and the statistical hadronization model, we estimate the yield of charmed
tetraquark meson and pentaquark baryon in heavy ion
collisions at RHIC and LHC. We further discuss the decay modes of these charmed
exotic hadrons in order to facilitate their detections in experiments
Particle dependence of elliptic flow in Au+Au collisions at 200 GeV
The elliptic flow parameter () for and
has been measured at mid-rapidity in Au + Au collisions at
GeV by the STAR collaboration. The values for both
and saturate at moderate , deviating
from the hydrodynamic behavior observed in the lower region. The
saturated values and the scales where the deviation begins are
particle dependent. The particle-type dependence of shows features
expected from the hadronization of a partonic ellipsoid by coalescence of
co-moving quarks. These results will be discussed in relation to the nuclear
modification factor () which has also been measured for and
by the STAR collaboration.Comment: 6 pages, 3 figures, Strange Quark Matter 2003 Conference (SQM 2003):
updated with 2 figures from original talk that did not appear in the journa
Evaluation of range of motion restriction within the hip joint
In Total Hip Arthroplasty, determining the impingement free range of motion requirement is a complex task. This is because in the native hip, motion is restricted by both impingement as well as soft tissue restraint. The aim of this study is to determine a range of motion benchmark which can identify motions which are at risk from impingement and those which are constrained due to soft tissue. Two experimental methodologies were used to determine motions which were limited by impingement and those motions which were limited by both impingement and soft tissue restraint. By comparing these two experimental results, motions which were limited by impingement were able to be separated from those motions which were limited by soft tissue restraint. The results show motions in extension as well as flexion combined with adduction are limited by soft tissue restraint. Motions in flexion, flexion combined with abduction and adduction are at risk from osseous impingement. Consequently, these motions represent where the maximum likely damage will occur in femoroacetabular impingement or at most risk of prosthetic impingement in Total Hip Arthroplasty
Knowledge Sharing and Knowledge Management System Avoidance: The Role of Knowledge Type and the Social Network in Bypassing an Organizational Knowledge Management System
Knowledge sharing is a difficult task for most organizations, and there are many reasons for this. In this article, we propose that the nature of the knowledge shared and an individual\u27s social network influence employees to find more value in person-to-person knowledge sharing, which could lead them to bypass the codified knowledge provided by a knowledge management system (KMS). We surveyed employees of a workman\u27s compensation board in Canada and used social network analysis and hierarchical linear modeling to analyze the data. The results show that knowledge complexity and knowledge teachability increased the likelihood of finding value in person-to-person knowledge transfer, but knowledge observability did not. Contrary to expectations, whether the knowledge was available in the KMS had no impact on the value of person-to-person knowledge transfer. In terms of the social network, individuals with larger networks tended to perceive more value in the person-to-person transfer of knowledge than those with smaller networks
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