Conditions driving chemical freeze-out

We propose the entropy density as the thermodynamic condition driving best the chemical freeze-out in heavy-ion collisions. Taking its value from lattice calculations at zero chemical potential, we find that it is excellent in reproducing the experimentally estimated freeze-out parameters. The two characteristic endpoints in the freeze-out diagram are reproduced as well.Comment: 8 pages, 5 eps figure

The influence of strange quarks on QCD phase diagram and chemical freeze-out: Results from the hadron resonance gas model

We confront the lattice results on QCD phase diagram for two and three flavors with the hadron resonance gas model. Taking into account the truncations in the Taylor-expansion of energy density $\epsilon$ done on the lattice at finite chemical potential $\mu$, we find that the hadron resonance gas model under the condition of constant $\epsilon$ describes very well the lattice phase diagram. We also calculate the chemical freeze-out curve according to the entropy density $s$. The $s$-values are taken from lattice QCD simulations with two and three flavors. We find that this condition is excellent in reproducing the experimentally estimated parameters of the chemical freeze-out.Comment: 5 pages, 3 figures and 1 table Talk given at VIIIth international conference on ''Strangeness in Quark Matter'' (SQM 2004), Cape Town, South Africa, Sep. 15-20 200

Entropy for Color Superconductivity in Quark Matter

We study a model for color superconductivity with both three colors and massless flavors including quark pairing. By using the Hamiltonian in the color-flavor basis we can calculate the quantum entropy. From this we are able to further investigate the phases of the color superconductor, for which we find a rather sharp transition to color superconductivity above a chemical potential around $290$MeV.Comment: 10 pages, 2 eps-figure

Band Symmetries and Singularities in Twisted Multilayer Graphene

The electronic spectra of rotationally faulted graphene bilayers are calculated using a continuum formulation for small fault angles that identifies two distinct electronic states of the coupled system. The low energy spectra of one state features a Fermi velocity reduction which ultimately leads to pairwise annihilation and regeneration of its low energy Dirac nodes. The physics in the complementary state is controlled by pseudospin selection rules that prevent a Fermi velocity renormalization and produce second generation symmetry-protected Dirac singularities in the spectrum. These results are compared with previous theoretical analyses and with experimental data.Comment: 5 pages, 3 figure

Entropy for SU(3)cSU(3)_c Quark States

We discuss the quantum state structure using the standard model for three colored quarks in the fundamental representations of $SU(3)_c$ making up the singlet ground state of the hadrons. This allows us to calculate a finite von Neumann entropy from the quantum reduced density matrix, which we explicitly evaluate for the quarks in a model for the meson and baryon states. Finally we look into the general effects and implications of entanglement in the $SU(3)_c$ color space.Comment: 9 pages, 0 figure

SRC seal testing

Small venthole drilled in semisealed silicon-controlled rectifier (SCR) cavity eliminates entrapped helium. Although these devices show slightly greater leak than those before lead installation, it is now possible to distinguish device with good hermetic seal from defective one

Linear growth of the trace anomaly in Yang-Mills thermodynamics

In the lattice work by Miller [1,2] and in the work by Zwanziger [3] a linear growth of the trace anomaly for high temperatures was found in pure SU(2) and SU(3) Yang-Mills theories. These results show the remarkable property that the corresponding systems are strong interacting even at high temperatures. We show that within an analytical approach to Yang-Mills thermodynamics this linear rise is obtained and is directly connected to the presence of a temperature-dependent ground state, which describes (part of) the nonperturbative nature of the Yang-Mills system. Our predictions are in approximate agreement with [1,2,3]Comment: 9 pages and 2 figure

Nonperturbative screening of the Landau pole

Based on the trace anomaly for the energy-momentum tensor, an effective theory for the thermodynamics of the deconfining phase, and by assuming the asymptotic behavior to be determined by one-loop perturbation theory we compute the nonperturbative beta function for the fundamental coupling $g$ in SU(2) and SU(3) Yang-Mills theory. With increasing temperature we observe a very rapid approach to the perturbative running. The Landau pole is nonperturbatively screened.Comment: 11 pages, 3 figure

Cross-calibration of Suzaku XIS and XMM-Newton EPIC using clusters of galaxies

We extend a previous cross-calibration study by the International Astronomical Consortium for High Energy Calibration (IACHEC) on XMM-Newton/EPIC, Chandra/ACIS and BeppoSAX/MECS X-ray instruments with clusters of galaxies to Suzaku/XIS instruments. Our aim is to study the accuracy of the energy-dependent effective area calibration of the XIS instruments by comparison of spectroscopic temperatures, fluxes and fit residuals obtained with Suzaku/XIS and XMM-Newton/EPIC-pn for the same cluster. The temperatures measured in the hard 2.0-7.0 keV energy band with all instruments are consistent within 5 %. However, temperatures obtained with the XIS instruments in the soft 0.5-2.0 keV band disagree by 9-29 %. We investigated residuals in the XIS soft band, which showed that if XIS0 effective area shape is accurately calibrated, the effective areas of XIS1 and XIS3 are overestimated below 1.0 keV (or vice versa). Adjustments to the modelling of the column density of the XIS contaminant in the 3-6 arcmin extraction region while forcing consistent emission models in each instrument for a given cluster significantly improved the fits. The oxygen column density in XIS1 and XIS3 contaminant must be increased by 1-2E17 cm^-2 in comparison to the values implemented in the current calibration, while the column density of the XIS0 contaminant given by the analysis is consistent with the public calibration. XIS soft band temperatures obtained with the modification to the column density of the contaminant agree better with temperatures obtained with the EPIC-pn instrument of XMM-Newton, than with those derived using the Chandra-ACIS instrument. However, comparison of hard band fluxes obtained using Suzaku-XIS to fluxes obtained using the Chandra-ACIS and EPIC-pn instruments proved inconclusive.Comment: 24 pages, 27 figures, accepted for publication in Astronomy & Astrophysic