941 research outputs found

    Recent results from NA61/SHINE and NA49

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    Preliminary results on particle spectra and fluctuations in inelastic p+p interactions measured by NA61/SHINE at the CERN SPS are presented and its future ion program is discussed. We also show results on the excitation functions of event-by-event particle ratio fluctuations in central Pb+Pb collisions from NA49 using a novel approach. We found a dependence of the results on phase space coverage which appears to explain the reported difference between measurements of NA49 and those of STAR in central Au+Au collisions

    Multiplicity Fluctuations of Identified Hadrons in Central Pb+Pb Collisions at the CERN

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    We report on the event-by-event multiplicity fluctuations of identified particles in central Pb+Pb collisions measured by the NA49 experiment at the CERN SPS. Employing a novel approach we unfolded the moments of the unknown multiplicity distributions of protons (p), kaons (K), pions (π) and electrons. Using these moments we reconstructed an excitation function of the fluctuation measure νdyn[A;B], with A and B denoting different particle types. Specifically, we reconstructed νdyn for the [p, π], [p, K] and [K, π] pairs. The energy dependence of νdyn is in agreement with previously published NA49 results on the related measure σdyn. Moreover, for [K; p] and [K;p] pairs, we discovered a dependence of the fluctuation measure νdyn on the phase space coverage (acceptance). Interestingly for the [p,π] case no significant acceptance dependence was observed. These observations provide a likely explanation of the reported differences between measurements of NA49 and those of STAR in central Au+Au collisions

    A model-free procedure to correct for volume fluctuations in E-by-E analyses of particle multiplicities

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    We develop an innovative and unbiased procedure, based on event mixing, to account for unavoidable contributions from volume (or system size) fluctuations to experimentally measured moments of particle multiplicity distributions produced in relativistic nuclear collisions. Within the wounded-nucleon model they are characterized by fluctuations of the number of wounded nucleons, the latter usually referred to as participants. For the first time we extract participant fluctuations directly from the data used for the fluctuation analysis, i.e., without involving model calculations. To achieve this we constructed a dedicated event-mixing algorithm that eliminates all possible correlations between produced particles while preserving the volume fluctuations. The procedure provides direct access to the cumulants of wounded-nucleon distributions, which can be used to account for non-critical contributions to the experimentally measured cumulants of multiplicity distributions

    QCD under extreme conditions

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    In nucleus-nucleus collisions at relativistic energies a new kind of matter is created, the Quark-Gluon Plasma (QGP). The phase diagram of such matter and the chemical freeze-out points will be presented in connection to the pseudo-critical temperature for the chiral cross over transition. The role of conserved charge fluctuations to give experimental access to the nature of the chiral phase transition will be summarized in terms of the relation to lattice QCD and the current experimental data. The QGP can be characterized as a nearly ideal liquid expanding hydrodynamically and the experimental data allow to extract transport parameters such as the bulk and shear viscosities. The energy loss of partons in the QGP probes the high parton density of the medium. The role of quarkonia and open charm hadrons as a probe of deconfinement and hadronization form the final topic.Comment: Article to appear in a special EPJC Volume in celebration of '50 Years of Quantum Chromodynamics' [arXiv:2212.11107

    Psychometric Evaluation of the Satisfaction With Life Scale (SWLS) in Azerbaijan

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    The Satisfaction With Life Scale (SWLS) is a globally recognized scale for the measurement of subjective well-being in more than thirty six languages. Currently there is no adapted version of the SWLS in Azerbaijani language. The aim of the present study was to complete forward and backward translations of the SWLS and maintaining equivalence to examine its psychometric properties in a sample of 374 subjects in Azerbaijan. The results showed that the Azerbaijani version of SWLS had good internal consistency (Cronbach’s α = 0.81) with confirmatory factor analysis showing a single factorial structure. The findings suggest that theAzerbaijani version of the SWLS is a valid instrument to use among Azerbaijan samples

    Methods to analysis of queueing models with state-dependent jump priorities

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    In this paper, exact and approximate approaches for studying queuing models with state-dependent jump priorities are developed. Both models with finite separate buffers and finite common buffer for heterogeneous calls are investigated. It is shown that both models might be described by twodimensional Markov Chains (2-D MC). Exact approach based on solution of appropriate system of balance equations (SBE) for state probabilities faced with big computational challenges for large scale models. To overcome the indicated difficulties an approximate approach based on the state space merging algorithms is developed. This approach allows to construct simple algorithms to calculate the Quality of Service (QoS) metrics of the examined models. The results of numerical experiments are demonstrated

    Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES

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    We present measurements of exclusive ensuremathπ+,0 and η production in pp reactions at 1.25GeV and 2.2GeV beam kinetic energy in hadron and dielectron channels. In the case of π+ and π0 , high-statistics invariant-mass and angular distributions are obtained within the HADES acceptance as well as acceptance-corrected distributions, which are compared to a resonance model. The sensitivity of the data to the yield and production angular distribution of Δ (1232) and higher-lying baryon resonances is shown, and an improved parameterization is proposed. The extracted cross-sections are of special interest in the case of pp → pp η , since controversial data exist at 2.0GeV; we find \ensuremathσ=0.142±0.022 mb. Using the dielectron channels, the π0 and η Dalitz decay signals are reconstructed with yields fully consistent with the hadronic channels. The electron invariant masses and acceptance-corrected helicity angle distributions are found in good agreement with model predictions
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