514 research outputs found
Kaon and production vs Participants in Nuclear Collisions
Data on kaon and production in nuclear collisions as a function of
centrality are analysed both at AGS and SPS energy range. We compare the
results of several experiments, looking for common trend in `participant
scaling' of production yields. We find a smooth description of scaled kaon and
yields as a function of participant density. We also show a participant
density dependence of kaons and produced in the forward hemisphere for
proton-nucleus collisions.Comment: Proceedings of the International Conference on Strangeness in Quark
Matter, 20-25 July 2000, Berkeley, CA. To appear in Journal of Physics G:
Nuclear and Particle Physic
Feasibility Studies for Single Transverse-Spin Asymmetry Measurements at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC)
The measurement of Single Transverse-Spin Asymmetries, A_N, for various quarkonium states and DrellâYan lepton pairs can shed light on the orbital angular momentum of quarks and gluons, a fundamental ingredient of the proton-spin puzzle. The AFTER@LHC proposal combines a unique kinematic coverage and large luminosities thanks to the Large Hadron Collider beams to deliver precise measurements, complementary to the knowledge provided by collider experiments such as at RHIC. In this paper, we report on sensitivity studies for J/ Ï, ΄ and DrellâYan A_N done using the performance of LHCb-like or ALICE-like detectors, combined with polarised gaseous hydrogen and helium-3 targets. In particular, such analyses will provide us with new insights and knowledge about transverse-momentum-dependent parton distribution functions for quarks and gluons and on twist-3 collinear matrix elements in the proton and the neutron
Chrysin-Loaded Microemulsion: Formulation Design, Evaluation and Antihyperalgesic Activity in Mice
Chrysin is a bioactive flavonoid found in pollens, passion flowers, honey, royal jelly, and propolis, which is commonly used as an ingredient in natural food supplements and is primarily re-sponsible for their pharmacological properties. A transparent chrysin-loaded microemulsion (CS-ME) prepared through a ternary phase diagram was evaluated for use as an antihyperalgesic formulation. It was formulated with 40% Labrasol\uae (surfactant), 5% isopropyl myristate (oil phase) and 55% water (aqueous phase) and classified as an oil-in-water (O/W) microsized system (74.4 \ub1 15.8 nm). Its negative Zeta potential ( 1216.1 \ub1 1.9 mV) was confirmed by polarized light microscopy and dynamic light scattering analysis. In vitro studies in Franz-type static diffusion cells showed that chrysin release from CS-ME followed zero-order kinetics. Oral administration of CS-ME in mice resulted in a statistically significantly reduction (p < 0.05) in carrageenan-induced mechanical hyperalgesia compared to the control group. Treatment with CS-ME also showed anti-inflammatory activity by significantly decreasing the TNF-\u3b1 level (p < 0.01) and increasing that of IL-10 (p < 0.05) compared to the control group. These results suggest that the proposed microsystem is a promising vector for the release of chrysin, being able to improve its capacity to modulate inflammatory and nociceptive responses
J/psi azimuthal anisotropy relative to the reaction plane in Pb-Pb collisions at 158 GeV per nucleon
The J/ azimuthal distribution relative to the reaction plane has been
measured by the NA50 experiment in Pb-Pb collisions at 158 GeV/nucleon. Various
physical mechanisms related to charmonium dissociation in the medium created in
the heavy ion collision are expected to introduce an anisotropy in the
azimuthal distribution of the observed J/ mesons at SPS energies. Hence,
the measurement of J/ elliptic anisotropy, quantified by the Fourier
coefficient v of the J/ azimuthal distribution relative to the
reaction plane, is an important tool to constrain theoretical models aimed at
explaining the anomalous J/ suppression observed in Pb-Pb collisions. We
present the measured J/ yields in different bins of azimuthal angle
relative to the reaction plane, as well as the resulting values of the Fourier
coefficient v as a function of the collision centrality and of the
J/ transverse momentum. The reaction plane has been estimated from the
azimuthal distribution of the neutral transverse energy detected in an
electromagnetic calorimeter. The analysis has been performed on a data sample
of about 100 000 events, distributed in five centrality or p
sub-samples. The extracted v values are significantly larger than zero
for non-central collisions and are seen to increase with p.Comment: proceedings of HP08 conference corrected a typo in one equatio
Antinociceptive effect of the ethanolic extract of Amburana cearensis (AllemĂŁo) A.C. Sm., Fabaceae, in rodents.
Efeito antinociceptivo do extrato etanĂłlico de Amburana cearensis (AllemĂŁo) A.C. Sm., Fabaceae, em roedores
The dependence of the anomalous J/psi suppression on the number of participant nucleons
The observation of an anomalous J/psi suppression in Pb-Pb collisions by the NA50 Collaboration can be considered as the most striking indication for the deconfinement of quarks and gluons at SPS energies. In this Letter, we determine the J/psi suppression pattern as a function of the forward hadronic energy E-ZDC measured in a Zero Degree Calorimeter (ZDC). The direct connection between EZDC and the geometry of the collision allows us to calculate, within a Glauber approach, the precise relation between the number of participant nucleons N-part and E-ZDC. Then, we check if the experimental data can be better explained by a sudden or a smooth onset of the anomalous J/psi suppression as a function of the number of participants. (C) 2001 Elsevier Science B.V. All rights reserved.info:eu-repo/semantics/publishedVersio
A new measurement of J/psi suppression in Pb-Pb collisions at 158 GeV per nucleon
We present a new measurement of J/psi production in Pb-Pb collisions at 158
GeV/nucleon, from the data sample collected in year 2000 by the NA50
Collaboration, under improved experimental conditions with respect to previous
years. With the target system placed in vacuum, the setup was better adapted to
study, in particular, the most peripheral nuclear collisions with unprecedented
accuracy. The analysis of this data sample shows that the (J/psi)/Drell-Yan
cross-sections ratio measured in the most peripheral Pb-Pb interactions is in
good agreement with the nuclear absorption pattern extrapolated from the
studies of proton-nucleus collisions. Furthermore, this new measurement
confirms our previous observation that the (J/psi)/Drell-Yan cross-sections
ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb
collisions and that this ratio persistently decreases up to the most central
collisions.Comment: 19 pages, 10 figures. Submitted to Eur. Phys. J.
Bottomonium and Drell-Yan production in p-A collisions at 450 GeV
The NA50 Collaboration has measured heavy-quarkonium production in p-A
collisions at 450 GeV incident energy (sqrt(s) = 29.1 GeV). We report here
results on the production of the Upsilon states and of high-mass Drell-Yan muon
pairs (m > 6 GeV). The cross-section at midrapidity and the A-dependence of the
measured yields are determined and compared with the results of other
fixed-target experiments and with the available theoretical estimates. Finally,
we also address some issues concerning the transverse momentum distributions of
the measured dimuons.Comment: 18 pages, 9 figures, to be published in Phys. Lett.
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