682 research outputs found
decays from photoproduction of -mesons off protons
A study of the partial-wave content of the
reaction in the fourth resonance region is presented, which has been prompted
by new measurements of polarization observables for that process. Using the
Bonn-Gatchina partial-wave formalism, the incorporation of new data indicates
that the , , , and are
the most significant contributors to the photoproduction process. New results
for the branching ratios of the decays of these more prominent resonances to
final states are provided; such branches have not been indicated
in the most recent edition of the Review of Particle Properties. Based on the
analysis performed here, predictions for the helicity asymmetry for the
reaction are presented.Comment: 7 pages, 5 figures, 3 table
Hadron Resonance Gas Model with Induced Surface Tension
Here we present a physically transparent generalization of the multicomponent
Van der Waals equation of state in the grand canonical ensemble. For the
one-component case the third and fourth virial coefficients are calculated
analytically. It is shown that an adjustment of a single model parameter allows
us to reproduce the third and fourth virial coefficients of the gas of hard
spheres with small deviations from their exact values. A thorough comparison of
the compressibility factor and speed of sound of the developed model with the
one and two component Carnahan-Starling equation of state is made. It is shown
that the model with the induced surface tension is able to reproduce the
results of the Carnahan-Starling equation of state up to the packing fractions
0.2-0.22 at which the usual Van der Waals equation of state is inapplicable. At
higher packing fractions the developed equation of state is softer than the gas
of hard spheres and, hence, it breaks causality in the domain where the
hadronic description is expected to be inapplicable. Using this equation of
state we develop an entirely new hadron resonance gas model and apply it to a
description of the hadron yield ratios measured at AGS, SPS, RHIC and ALICE
energies of nuclear collisions. The achieved quality of the fit per degree of
freedom is about 1.08. We confirm that the strangeness enhancement factor has a
peak at low AGS energies, while at and above the highest SPS energy of
collisions the chemical equilibrium of strangeness is observed. We argue that
the chemical equilibrium of strangeness, i.e. , observed
above the center of mass collision energy 4.3 GeV may be related to the
hadronization of quark gluon bags which have the Hagedorn mass spectrum, and,
hence, it may be a new signal for the onset of deconfinement
Communicative discourse of terminology used in gastronomical media culture
This article aims to analyze and describe the food discourse and terms of the French language, as well as to determine correlations with the French national and cultural worldview. The study also considers the current state of "gastronomical discourse" based on the French food semiotic and communicative mode
Anomalous radial expansion in central heavy-ion reactions
The expansion velocity profile in central heavy-ion reactions in the Fermi
energy domain is examined. The radial expansion is non-hubblean and in the
surface region it scales proportional to a higher exponent () of
the radius. The anomalous expansion velocity profile is accompanied by a power
law nucleon density profile in the surface region. Both these features of
central heavy-ion reactions disappear at higher energies, and the system
follows a uniform Hubble expansion ()
Hadronization of massive quark matter
We present a fast hadronization model for the constituent quark plasma (CQP)
produced in relativistic heavy ion collisions at SPS. The model is based on
rate equations and on an equation of state inspired by the string
phenomenology. This equation of state has a confining character. We display the
time evolution of the relevant physical quantities during the hadronization
process and the final hadron multiplicities. The results indicate that the
hadronization of CQP is fast.Comment: 12 pages, Latex, 2 EPS figures, contribution to the Proceedings of
the 4th International Conference on Strangeness in Quark Matter (SQM'98),
Padova, Italy, 20-24 July 199
Strangeness dynamics and transverse pressure in relativistic nucleus-nucleus collisions
We investigate hadron production as well as transverse hadron spectra from
proton-proton, proton-nucleus and nucleus-nucleus collisions from 2 GeV
to 21.3 TeV within two independent transport approaches (HSD and UrQMD)
that are based on quark, diquark, string and hadronic degrees of freedom. The
comparison to experimental data on transverse mass spectra from , and
C+C (or Si+Si) reactions shows the reliability of the transport models for
light systems. For central Au+Au (Pb+Pb) collisions at bombarding energies
above 5 AGeV, furthermore, the measured transverse mass
spectra have a larger inverse slope parameter than expected from the default
calculations. We investigate various scenarios to explore their potential
effects on the spectra. In particular the initial state Cronin effect
is found to play a substantial role at top SPS and RHIC energies. However, the
maximum in the ratio at 20 to 30 AGeV is missed by ~40% and
the approximately constant slope of the spectra at SPS energies is not
reproduced either. Our systematic analysis suggests that the additional
pressure - as expected from lattice QCD calculations at finite quark chemical
potential and temperature - should be generated by strong
interactions in the early pre-hadronic/partonic phase of central Au+Au (Pb+Pb)
collisions.Comment: 20 pages, 15 figures, Phys. Rev. C, in pres
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Grazing incidence neutron diffraction from large scale 2D structures
The distorted wave Born approximation (DWBA) is applied to evaluate the diffraction pattern of neutrons (or X-rays) from a 2D array of dots deposited onto a dissimilar substrate. With the radiation impinging on the surface at a grazing incidence angle {alpha}, the intensities diffracted both in and out the plane of specular reflection are calculated as a function of the periodicity of the array, height and diameter of the dots. The results are presented in the form of diffracted intensity contours in a plane with coordinates {alpha} and {alpha}{prime}, the latter being the glancing angle of scattering. The optimization of the experimental conditions for polarized neutron experiments on submicron dots is discussed. The feasibility of such measurements is confirmed by a test experiment
Parameters of communication behavior and national language
Analyze the category of "language behavior" in modern linguistic research. It states provisions of the communicative interpretation of the logical-semantic structure of utterances to determine their ethnocultural feature
Photon Beam Asymmetry Σ for η and η′ Photoproduction From the Proton
Measurements of the linearly-polarized photon beam asymmetry Σ for photoproduction from the proton of η and η ′ mesons are reported. A linearly-polarized tagged photon beam produced by coherent bremsstrahlung was incident on a cryogenic hydrogen target within the CEBAF Large Acceptance Spectrometer. Results are presented for the γ p → η p reaction for incident photon energies from 1.070 to 1.876 GeV, and from 1.516 to 1.836 GeV for the γ p → η ′ p reaction. For γ p → η p , the data reported here considerably extend the range of measurements to higher energies, and are consistent with the few previously published measurements for this observable near threshold. For γ p → η ′ p , the results obtained are consistent with the few previously published measurements for this observable near threshold, but also greatly expand the incident photon energy coverage for that reaction. Initial analysis of the data reported here with the Bonn–Gatchina model strengthens the evidence for four nucleon resonances – the N (1895) 1/2− , N (1900) 3/2+ , N(2100) 1/2+ and N (2120) 3/2− resonances – which presently lack the four-star status in the current Particle Data Group compilation, providing examples of how these new measurements help refine models of the photoproduction process
Requirements for a global data infrastructure in support of CMIP6
The World Climate Research Programme (WCRP)’s Working Group on Climate Modelling (WGCM) Infrastructure Panel (WIP) was formed in 2014 in response to the explosive growth in size and complexity of Coupled Model Intercomparison Projects (CMIPs) between CMIP3 (2005–2006) and CMIP5 (2011–2012). This article presents the WIP recommendations for the global data infrastruc- ture needed to support CMIP design, future growth, and evolution. Developed in close coordination with those who build and run the existing infrastructure (the Earth System Grid Federation; ESGF), the recommendations are based on several principles beginning with the need to separate requirements, implementation, and operations. Other im- portant principles include the consideration of the diversity of community needs around data – a data ecosystem – the importance of provenance, the need for automation, and the obligation to measure costs and benefits.
This paper concentrates on requirements, recognizing the diversity of communities involved (modelers, analysts, soft- ware developers, and downstream users). Such requirements include the need for scientific reproducibility and account-
ability alongside the need to record and track data usage. One key element is to generate a dataset-centric rather than system-centric focus, with an aim to making the infrastruc- ture less prone to systemic failure.
With these overarching principles and requirements, the WIP has produced a set of position papers, which are summa- rized in the latter pages of this document. They provide spec- ifications for managing and delivering model output, includ- ing strategies for replication and versioning, licensing, data quality assurance, citation, long-term archiving, and dataset tracking. They also describe a new and more formal approach for specifying what data, and associated metadata, should be saved, which enables future data volumes to be estimated, particularly for well-defined projects such as CMIP6.
The paper concludes with a future facing consideration of the global data infrastructure evolution that follows from the blurring of boundaries between climate and weather, and the changing nature of published scientific results in the digital age
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