53 research outputs found
General thoughts to the Kaon pair production in the threshold region
Simple--minded thoughts about the cross sections for the reactions
pp-->ppK+K- and pp-->ppK0K0 are presented, which certainly do not account for
the complex coupled channel problem but rather provide some ideas into the
mutual reaction dynamics.Comment: Talk given at 9th International Workshop on Meson Production,
Properties and Interaction, Cracow, Poland, 9-13 June 2006. 3 pages, 2
figure
Eta and eta' mesons production at COSY-11
The low emittance and small momentum spread of the proton and deuteron beams
of the Cooler Synchrotron COSY combined with the high mass resolution of the
COSY-11 detection system permit to study the creation of mesons in the
nucleon-nucleon interaction down to the fraction of MeV with respect to the
kinematical threshold. At such small excess energies, the ejectiles possess low
relative momenta and are predominantly produced with the relative angular
momentum equal to zero. Taking advantage of these conditions we have performed
investigations aiming to determine the mechanism of the production of eta and
eta' mesons in the collision of hadrons as well as the hadronic interaction of
these mesons with nucleons and nuclei. In this proceedings we address the
ongoing studies of the spin and isospin dependence for the production of the
eta and eta' mesons in free and quasi-free nucleon-nucleon collisions. New
results on the spin observables for the vec(p)p --> pp eta reaction, combined
with the previously determined total cross section isospin dependence, reveal a
statistically significant indication that the excitation of the nucleon to the
S11(1535) resonance, the process which intermediates the production of the eta
meson in the nucleon-nucleon interactions, is predominantly due to the exchange
of the pi meson between the colliding nucleons.Comment: Invited talk at MESON 2006: 9th International Workshop on Meson
Production, Properties and Interactions, Cracow, Poland, 9-13 Jun 200
Study of the 3He-eta system in d-p collisions at COSY-11
We present preliminary results from dp --> 3He X (X=pi0,eta) measurements
near the eta production threshold. The data were taken during a slow ramping of
the COSY internal deuteron beam scattered on a proton target. The 3He ejectiles
were registered with the COSY-11 detection setup. The ongoing data analysis
should deliver high precision data for the dp --> 3He eta total and
differential cross sections for the excess energies in the range from threshold
up to 9 MeV. The preliminary excitation function for the reaction dp --> 3He
pi0 does not show any structure which could originate from the decay of 3He-eta
bound state. We present also a threshold excitation curve for the dp --> 3He X
channel. Contrary to corresponding results from SATURNE we see no cusp in the
vicinity of the eta threshold.Comment: 8 pages; 5 figures; Talk at Eta05 Workshop on Production and Decay of
eta and eta-prime Mesons, Cracow, Poland, 15-18 Sep 2005; Acta Phys. Slovaca,
in prin
Dynamics of the near threshold eta meson production in proton-proton interaction
We present the results of measurements of the analysing power for the p(pol)p
--> pp eta reaction at the excess energies of Q=10 and 36 MeV, and interpret
these results within the framework of the meson exchange models. The determined
values of the analysing power at both excess energies are consistent with zero
implying that the eta meson is produced predominantly in s-wave.Comment: 3 pages, 3 figures, Presented at the Workshop on the physics of
excited nucleons (NSTAR 2007), 5-8 September 2007, Bonn, German
ScreenTrack: Using a Visual History of a Computer Screen to Retrieve Documents and Web Pages
Computers are used for various purposes, so frequent context switching is
inevitable. In this setting, retrieving the documents, files, and web pages
that have been used for a task can be a challenge. While modern applications
provide a history of recent documents for users to resume work, this is not
sufficient to retrieve all the digital resources relevant to a given primary
document. The histories currently available do not take into account the
complex dependencies among resources across applications. To address this
problem, we tested the idea of using a visual history of a computer screen to
retrieve digital resources within a few days of their use through the
development of ScreenTrack. ScreenTrack is software that captures screenshots
of a computer at regular intervals. It then generates a time-lapse video from
the captured screenshots and lets users retrieve a recently opened document or
web page from a screenshot after recognizing the resource by its appearance. A
controlled user study found that participants were able to retrieve requested
information more quickly with ScreenTrack than under the baseline condition
with existing tools. A follow-up study showed that the participants used
ScreenTrack to retrieve previously used resources and to recover the context
for task resumption.Comment: CHI 2020, 10 pages, 7 figure
Correlation Femtoscopy for Studying Eta Meson Production Mechanism
The high statistics data from the pp -> ppeta reaction measurement, delivered
by the COSY-11 collaboration, are now being evaluated using the correlation
femtoscopy technique. This method is based on the relative momentum
correlations of two emitted protons and may permit determination of the size of
the reaction volume. For the very first time, we apply an intensity
interferometry technique to study the mechanism of the meson production via the
nucleon-nucleon interaction close to the kinematical threshold. We invented a
method to determine correlation function for the ppeta system free from the
physical multi-pion production background. We show the comparison of
experimental results with theoretical predictions and appraise the accuracy
achieved for the determination of the size of the emission source.Comment: Talk presented at Eta05: Workshop on Production and Decay of eta and
eta-prime Mesons, Cracow, Poland, 15-18 Sep 200
Near threshold production of the eta meson via the quasi-free pn --> pn eta reaction
Total cross sections for the quasi-free pn --> pn eta reaction in the range
from the kinematical threshold up to 20 MeV excess energy have been determined.
At threshold they exceed corresponding cross sections for the pp --> pp eta
reaction by a factor of about three in contrast to the factor of six
established for higher excess energies. To large extent, the observed decrease
of the ratio sigma(pn --> pn eta)/sigma(pp --> pp eta) towards threshold may be
assigned to the different energy dependence of the proton-proton and
proton-neutron final state interactions.
The experiment has been conducted using a proton beam of the cooler
synchrotron COSY and a cluster jet deuteron target. The proton-neutron
reactions were tagged by the spectator proton whose momentum was measured for
each event. Protons and neutron outgoing from the pn --> pn eta reaction have
been registered by means of the COSY-11 facility, an apparatus dedicated for
threshold meson production.Comment: 15 pages, 6 figures, submitted to Phys. Rev.
New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk
To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10−8), of which eight were previously associated with increased overall adiposity (BMI, BF%) and four (in or near COBLL1/GRB14, IGF2BP1, PLA2G6, CRTC1) were novel associations with BF%. Seven loci showed a larger effect on BF% than on BMI, suggestive of a primary association with adiposity, while five loci showed larger effects on BMI than on BF%, suggesting association with both fat and lean mass. In particular, the loci more strongly associated with BF% showed distinct cross-phenotype association signatures with a range of cardiometabolic traits revealing new insights in the link between adiposity and disease risk
New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk
To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P <5 x 10(-8)), of which eight were previously associated with increased overall adiposity (BMI, BF%) and four (in or near COBLL1/GRB14, IGF2BP1, PLA2G6, CRTC1) were novel associations with BF%. Seven loci showed a larger effect on BF% than on BMI, suggestive of a primary association with adiposity, while five loci showed larger effects on BMI than on BF%, suggesting association with both fat and lean mass. In particular, the loci more strongly associated with BF% showed distinct cross-phenotype association signatures with a range of cardiometabolic traits revealing new insights in the link between adiposity and disease risk.Peer reviewe
- …