MCSTHAR++, a Monte Carlo code for the microcanonical hadronization

MCSTHAR++ is a new Monte Carlo code implementing the Statistical Hadronization Model. This model assumes that hadronization proceeds through the microcanonical decay of massive extended clusters. Unlike other hadronization models, in this approach very few free parameters are needed, as has been demonstrated in previous studies. The tuning of the model and the comparison with the data is ongoing.Comment: 3 pages; To appear in the proceedings of the conference IFAE 2010, Roma, Italy, 7-9 April 201

A Monte-Carlo generator for statistical hadronization in high energy e+e- collisions

We present a Monte-Carlo implementation of the Statistical Hadronization Model in e+e- collisions. The physical scheme is based on the statistical hadronization of massive clusters produced by the event generator Herwig within the microcanonical ensemble. We present a preliminary comparison of several observables with measurements in e+e- collisions at the Z peak. Although a fine tuning of the model parameters is not carried out, a general good agreement between its predictions and data is found.Comment: 19 pages, 28 figures, 6 tables. v2: added sections on comparison between the Statistical Hadronization Model and the Cluster Model and on the interplay between Herwig cluster splitting algorithm and Statistical Hadronization Model predictions. Fixed typos and references added. Version accepted for publication in EPJ

Strangeness counting in high energy collisions

The estimates of overall strange quark production in high energy e+e-, pp and ppbar collisions by using the statistical-thermal model of hadronisation are presented and compared with previous works. The parametrization of strangeness suppression within the model is discussed. Interesting regularities emerge in the strange/non-strange produced quark ratio which turns out to be fairly constant in elementary collisions while it is twice as large in SPS heavy ion collision.Comment: talk given at Strangeness in Quark Matter 98, submitted to J. Phys.

System Size Dependence of Particle Production at the SPS

Recent results on the system size dependence of net-baryon and hyperon production as measured at the CERN SPS are discussed. The observed Npart dependences of yields, but also of dynamical properties, such as average transverse momenta, can be described in the context of the core corona approach. Other observables, such as antiproton yields and net-protons at forward rapidities, do not follow the predictions of this model. Possible implications for a search for a critical point in the QCD phase diagram are discussed. Event-by-event fluctuations of the relative core to corona source contributions might influence fluctuation observables (e.g. multiplicity fluctuations). The magnitude of this effect is investigated.Comment: 10 pages, 4 figurs. Proceedings of the 6th International Workshop on Critical Point and Onset of Deconfinement in Dubna, Aug. 201

Possible Resolutions of the D-Paradox

We propose possible ways of explaining the net charge event-by-event fluctuations in Au+Au collisions at the Relativistic Heavy Ion Collider within a quark recombination model. We discuss various methods of estimating the number of quarks at recombination and their implications for the predicted net charge fluctuations. We also discuss the possibility of diquark and quark-antiquark clustering above the deconfinement temperature.Comment: 5 pages, 2 figure

Role of heparin prophylaxis at different doses in patients with COVID-19 and respiratory failure: a systematic review and meta-analysis

Abstract Background Venous thromboembolism (VTE) is common in patients with coronavirus disease-2019 (COVID-19). The use of heparin at higher doses than prophylactic is advocated, but the optimal regimens remain unknown due to the balance between prevention of thromboembolic events and bleeding risks. Objective To systematically review and perform a meta-analysis aimed at evaluating the risk of VTE and of major bleeding (MB) in patients with respiratory failure due to COVID-19 according to heparin doses. Methods We performed a systematic search in MEDLINE up until 22 March 2021. Studies on patients with respiratory failure due to COVID-19 were included if reported on study outcomes according to standard prophylactic and to higher heparin doses and included more than 10 patients. Study primary outcome was VTE; secondary outcomes were MB, all-cause death, fatal bleeding and fatal pulmonary embolism (PE). Results Overall, 2 randomized and 16 observational studies were selected (3458 patients). In 13 studies (2492 patients) VTE events were similar in patients receiving standard prophylaxis or higher heparin doses (RR 1.06, 95% CI 0.58–1.95, I2 87%; only randomized studies RR 1.72, 95% CI 0.78–3.81, I2 54%). 16 studies (3174) reporting on MB and showed a significant reduction in favor of standard heparin prophylaxis (RR 0.39, 95% CI 0.28–0.53, I2 8%). No differences were observed for overall mortality according to heparin doses (RR 1.11, 95% CI 0.88–1.40, I2 68%; in 8 studies, 2448 patients). Similarly, no differences were observed for fatal bleedings and fatal PEs. In the subanalysis of studies reporting only on intensive care unit patients (ICU) an increase in the risk of VTE (RR 1.86, 95% CI 1.28–2.72, I2 18%) and a reduction on the risk of MB (RR 0.60, 95% CI 0.40–0.90, I2 0%) were observed in patients receiving standard heparin doses compared to higher doses. Overall mortality was similar (RR 1.09, 95% CI 0.86–1.39, I2 64%). Conclusion Different doses of heparin prophylaxis seem to not affect the risk of VTE in the overall patients with COVID-19 and respiratory failure. In studies reporting only on ICU patients the risk of VTE was lower when higher heparin doses were used compared to standard doses, but with no advantage in overall death and with an increase of MBs. Funding Acknowledgement Type of funding sources: None

The QCD confinement transition: hadron formation

We review the foundations and the applications of the statistical and the quark recombination model as hadronization models.Comment: 45 pages, 16 figures, accepted for publication in Landolt-Boernstein Volume 1-23

The canonical partition function for relativistic hadron gases

Particle production in high-energy collisions is often addressed within the framework of the thermal (statistical) model. We present a method to calculate the canonical partition function for the hadron resonance gas with exact conservation of the baryon number, strangeness, electric charge, charmness and bottomness. We derive an analytical expression for the partition function which is represented as series of Bessel functions. Our results can be used directly to analyze particle production yields in elementary and in heavy ion collisions. We also quantify the importance of quantum statistics in the calculations of the light particle multiplicities in the canonical thermal model of the hadron resonance gas.Comment: 10 pages, 2 figures; submitted for publication in EPJ

Multiplicity Distributions in Canonical and Microcanonical Statistical Ensembles

The aim of this paper is to introduce a new technique for calculation of observables, in particular multiplicity distributions, in various statistical ensembles at finite volume. The method is based on Fourier analysis of the grand canonical partition function. Taylor expansion of the generating function is used to separate contributions to the partition function in their power in volume. We employ Laplace's asymptotic expansion to show that any equilibrium distribution of multiplicity, charge, energy, etc. tends to a multivariate normal distribution in the thermodynamic limit. Gram-Charlier expansion allows additionally for calculation of finite volume corrections. Analytical formulas are presented for inclusion of resonance decay and finite acceptance effects directly into the system partition function. This paper consolidates and extends previously published results of current investigation into properties of statistical ensembles.Comment: 53 pages, 7 figure

Unified Description of Freeze-Out Parameters in Relativistic Heavy Ion Collisions

It is shown that the chemical freeze-out parameters obtained at CERN/SPS, BNL/AGS and GSI/SIS energies all correspond to a unique value of 1 GeV per hadron in the local rest frame of the system, independent of the beam energy and of the target and beam particles.Comment: revtex, 1 figur