Is there still any Tc mystery in lattice QCD? Results with physical masses in the continuum limit III

The present paper concludes our investigations on the QCD cross-over transition temperatures with 2+1 staggered flavours and one-link stout improvement. We extend our previous two studies [Phys. Lett. B643 (2006) 46, JHEP 0906:088 (2009)] by choosing even finer lattices ($N_t$=16) and we work again with physical quark masses. The new results on this broad cross-over are in complete agreement with our earlier ones. We compare our findings with the published results of the hotQCD collaboration. All these results are confronted with the predictions of the Hadron Resonance Gas model and Chiral Perturbation Theory for temperatures below the transition region. Our results can be reproduced by using the physical spectrum in these analytic calculations. The findings of the hotQCD collaboration can be recovered by using a distorted spectrum which takes into account lattice discretization artifacts and heavier than physical quark masses. This analysis provides a simple explanation for the observed discrepancy in the transition temperatures between our and the hotQCD collaborations.Comment: 25 pages, 10 figures and 3 table

Fluctuations of conserved charges at finite temperature from lattice QCD

We present the full results of the Wuppertal-Budapest lattice QCD collaboration on flavor diagonal and non-diagonal quark number susceptibilities with 2+1 staggered quark flavors, in a temperature range between 125 and 400 MeV. The light and strange quark masses are set to their physical values. Lattices with Nt=6, 8, 10, 12, 16 are used. We perform a continuum extrapolation of all observables under study. A Symanzik improved gauge and a stout-link improved staggered fermion action is utilized. All results are compared to the Hadron Resonance Gas model predictions: good agreement is found in the temperature region below the transition.Comment: 13 pages, 8 figures in Jhep styl

Lattice QCD at the physical point meets S U (2 ) chiral perturbation theory

We perform a detailed, fully-correlated study of the chiral behavior of the pion mass and decay constant, based on 2+1 flavor lattice QCD simulations. These calculations are implemented using tree-level, O(a)-improved Wilson fermions, at four values of the lattice spacing down to 0.054 fm and all the way down to below the physical value of the pion mass. They allow a sharp comparison with the predictions of SU(2) chiral perturbation theory (\chi PT) and a determination of some of its low energy constants. In particular, we systematically explore the range of applicability of NLO SU(2) \chi PT in two different expansions: the first in quark mass (x-expansion), and the second in pion mass (\xi-expansion). We find that these expansions begin showing signs of failure around M_\pi=300 MeV for the typical percent-level precision of our N_f=2+1 lattice results. We further determine the LO low energy constants (LECs), F=88.0 \pm 1.3\pm 0.3 and B^\msbar(2 GeV)=2.58 \pm 0.07 \pm 0.02 GeV, and the related quark condensate, \Sigma^\msbar(2 GeV)=(271\pm 4\pm 1 MeV)^3, as well as the NLO ones, l_3=2.5 \pm 0.5 \pm 0.4 and l_4=3.8 \pm 0.4 \pm 0.2, with fully controlled uncertainties. We also explore the NNLO expansions and the values of NNLO LECs. In addition, we show that the lattice results favor the presence of chiral logarithms. We further demonstrate how the absence of lattice results with pion masses below 200 MeV can lead to misleading results and conclusions. Our calculations allow a fully controlled, ab initio determination of the pion decay constant with a total 1% error, which is in excellent agreement with experiment

The impact of current and future control measures on the spread of COVID-19 in Germany

The novel coronavirus (SARS-CoV-2), identified in China at the end of December 2019 and causing the disease COVID-19, has meanwhile led to outbreaks all over the globe with about 2.2 million confirmed cases and more than 150,000 deaths as of April 17, 2020 [37]. In view of most recent information on testing activity [32], we present here an update of our initial work [4]. In this work, mathematical models have been developed to study the spread of COVID-19 among the population in Germany and to asses the impact of non-pharmaceutical interventions. Systems of differential equations of SEIR type are extended here to account for undetected infections, as well as for stages of infections and age groups. The models are calibrated on data until April 5, data from April 6 to 14 are used for model validation. We simulate different possible strategies for the mitigation of the current outbreak, slowing down the spread of the virus and thus reducing the peak in daily diagnosed cases, the demand for hospitalization or intensive care units admissions, and eventually the number of fatalities. Our results suggest that a partial (and gradual) lifting of introduced control measures could soon be possible if accompanied by further increased testing activity, strict isolation of detected cases and reduced contact to risk groups

A first study on the impact of current and future control measures on the spread of COVID-19 in Germany

The novel coronavirus (SARS-CoV-2), identified in China at the end of December 2019 and causing the disease COVID-19, has meanwhile led to outbreaks all over the globe, with about 571,700 confirmed cases and about 26,500 deaths as of March 28th, 2020. We present here the preliminary results of a mathematical study directed at informing on the possible application or lifting of control measures in Germany. The developed mathematical models allow to study the spread of COVID-19 among the population in Germany and to asses the impact of non-pharmaceutical interventions

Platelet activation and increased tissue factor expression on monocytes in reperfusion injury following orthotopic liver transplantation

Platelets have been implicated in the pathogenesis of liver damage after orthotopic liver transplantation (OLT). Early graft dysfunction is frequently caused by reperfusion injury subsequent to cold ischemia (IRI). Therefore, we investigated activation of the pivotal haemostatic cells, platelets and monocytes, from patients with elevated markers of IRI and from patients with uneventful course (control-group), respectively during the first week after OLT. Flow cytometry analysis of citrate anticoagulated blood samples revealed that platelets from IRI patients became significantly activated within 48 h after OLT in vivo, with increased surface presentation of P-selectin, CD40L, thrombospondin-1 and tissue-factor. Platelet activation in IRI patients on post-transplant day 2 was accompanied by significantly enhanced tissue-factor expression on peripheral blood monocytes, significant elevated levels of C-reactive protein and hepatocellular damage. Towards post-transplant day 4, levels of platelet-derived microparticles rose significantly in IRI patients if contrasted to control patients. Thus, activated cellular haemostasis is involved in the early inflammatory response of hepatocellular damage subsequent to reperfusion of the transplanted liver. Targeting distinct activation patterns of platelets and monocytes in an early phase of hepatic grafting may counteract the extent of IRI via inhibition of micro-thrombus formation and inflammation without exacerbating the existing bleeding risk