1,604 research outputs found
Strangeness Production in Light and Intermediate size Nucleus-Nucleus Collisions
Within the statistical model, the net strangeness conservation and incomplete
total strangeness equilibration lead to the suppression of strange particle
multiplicities. Furthermore, suppression effects appear to be stronger in small
systems. By treating the production of strangeness within the canonical
ensemble formulation we developed a simple model which allows to predict the
excitation function of ratio in nucleus-nucleus collisions. In
doing so we assumed that different values of , measured in p+p and
Pb+Pb interactions at the same collision energy per nucleon, are driven by the
finite size effects only. These predictions may serve as a baseline for
experimental results from NA61/SHINE at the CERN SPS and the future CBM
experiment at FAIR
Strongly Intensive Measures for Multiplicity Fluctuations
The recently proposed two families of strongly intensive measures of
fluctuations and correlations are studied within Hadron-String-Dynamics (HSD)
transport approach to nucleus-nucleus collisions. We consider the measures
and for kaon and pion multiplicities in Au+Au
collisions in a wide range of collision energies and centralities. These
strongly intensive measures appear to cancel the participant number
fluctuations. This allows to enlarge the centrality window in the analysis of
event-by-event fluctuations up to at least of 10% most central collisions. We
also present a comparison of the HSD results with the data of NA49 and STAR
collaborations. The HSD describes reasonably well. However, the
HSD results depend monotonously on collision energy and do not reproduce the
bump-deep structure of observed from the NA49 data in the
region of the center of mass energy of nucleon pair
GeV. This fact deserves further studies. The origin of this `structure' is not
connected with simple geometrical or limited acceptance effects, as these
effects are taken into account in the HSD simulations
Adaptive potential of durum wheat (Triticum durum Desf.) varieties of Azerbaijan
Background. Studies into the adaptability of the genetic diversity of cultivated plants and their wild relatives to various environments are induced by global climate change. Introduction of adaptive wheat cultivars resistant to environmental stressors is the basis for stable harvests. This article presents the results of a research into the adaptive value of indigenous durum wheat varieties and improved cultivars released in different years in Azerbaijan.Materials and methods. The experiments were carried out in the foothills of Mountainous Shirvan under unsecured non-irrigation at Gobustan Experiment Station of the Research Institute of Crop Husbandry. In 2012–2014, contrasting in weather conditions, levels and structure of yield were analyzed. VIR’s guidelines were used to study 42 durum wheat varie ties, including 10 landraces. The years of study differed sharply in rainfall. Selyaninov’s hydrothermal coefficient was used to assess the conditions of growing seasons.Results. Mostly modern cultivars of the semi-intensive type were distinguished for a set of agrobiological traits. Adaptability coefficients (0.81–1.23) showed that the response of the studied varieties to unfavorable conditions was highly expressed. Indigenous landraces ‘Ag bughda’ and ‘Bozak’, old breeding varieties ‘Arandani’, ‘Ag bughda 13’, ‘Kahraba’ and ‘Mirbashir 50’, and new cultivars ‘Karagilchig 2’ and ‘Barakatli 95’ had the highest adaptability coefficients. The first of them demonstrated stable yield, and the latter two were also resistant to stressors.Conclusion. Durum wheat yields under the conditions of moderately continental climate in Mountainous Shirvan depended on the number and weight of grains per ear. The varieties identified for the best adaptability are recommended to be included in crosses to develop new plastic cultivars of durum wheat
Production of deuterium, tritium, and He in central Pb+Pb collisions at 20A, 30A, 40A, 80A, and 158A GeV at the CERN SPS
Production of , , and He nuclei in central Pb+Pb interactions was
studied at five collision energies ( 6.3, 7.6, 8.8, 12.3, and
17.3 GeV) with the NA49 detector at the CERN SPS. Transverse momentum spectra,
rapidity distributions, and particle ratios were measured. Yields are compared
to predictions of statistical models. Phase-space distributions of light nuclei
are discussed and compared to those of protons in the context of a coalescence
approach. The coalescence parameters and , as well as coalescence
radii for and He were determined as a function of transverse mass at
all energies.Comment: 22 pages, 29 figures, 8 tables, for submission to Phys. Rev.
Partial Wave Analysis of the Reaction to Search for the "" Bound State
Employing the Bonn-Gatchina partial wave analysis framework (PWA), we have
analyzed HADES data of the reaction . This
reaction might contain information about the kaonic cluster "" via its
decay into . Due to interference effects in our coherent description
of the data, a hypothetical (or, specifically "")
cluster signal must not necessarily show up as a pronounced feature (e.g. a
peak) in an invariant mass spectra like . Our PWA analysis includes a
variety of resonant and non-resonant intermediate states and delivers a good
description of our data (various angular distributions and two-hadron invariant
mass spectra) without a contribution of a cluster. At a
confidence level of CL=95\% such a cluster can not contribute more than
2-12\% to the total cross section with a final state, which
translates into a production cross-section between 0.7 and 4.2 ,
respectively. The range of the upper limit depends on the assumed cluster mass,
width and production process.Comment: 7 Pages, 5 Figure
Deep sub-threshold production in Ar+KCl reactions at 1.76A GeV
We report first results on a deep sub-threshold production of the doubly
strange hyperon in a heavy-ion reaction. At a beam energy of 1.76A GeV
the reaction Ar+KCl was studied with the High Acceptance Di-Electron
Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity
sample was collected, allowing for the investigation of the decay channel
. The deduced production
ratio of is significantly larger
than available model predictions.Comment: 4 pages, including 4 figure
Inclusive pion and eta production in p+Nb collisions at 3.5 GeV beam energy
Data on inclusive pion and eta production measured with the dielectron
spectrometer HADES in the reaction p+93Nb at a kinetic beam energy of 3.5 GeV
are presented. Our results, obtained with the photon conversion method,
supplement the rather sparse information on neutral meson production in
proton-nucleus reactions existing for this bombarding energy regime. The
reconstructed e+e-e+e- transverse-momentum and rapidity distributions are
confronted with transport model calculations, which account fairly well for
both pi0 and eta production.Comment: 12 pages, 9 figures, submitted to Physical Review
Production of Sigma{\pm}pi?pK+ in p+p reactions at 3.5 GeV beam energy
We study the production of Sigma^+-pi^+-pK^+ particle quartets in p+p
reactions at 3.5 GeV kinetic beam energy. The data were taken with the HADES
experiment at GSI. This report evaluates the contribution of resonances like
Lambda(1405$, Sigma(1385)^0, Lambda(1520), Delta(1232), N^* and K^*0 to the
Sigma^+- pi^-+ p K+ final state. The resulting simulation model is compared to
the experimental data in several angular distributions and it shows itself as
suitable to evaluate the acceptance corrections properly.Comment: 15 pages, 5 figure
- …