Phase diagram of QCD at finite temperature and chemical potential from lattice simulations with dynamical Wilson quarks

We present the first results for lattice QCD at finite temperature $T$ and chemical potential $\mu$ with four flavors of Wilson quarks. The calculations are performed using the imaginary chemical potential method at $\kappa=0$, 0.001, 0.15, 0.165, 0.17 and 0.25, where $\kappa$ is the hopping parameter, related to the bare quark mass $m$ and lattice spacing $a$ by $\kappa=1/(2ma+8)$. Such a method allows us to do large scale Monte Carlo simulations at imaginary chemical potential $\mu=i \mu_I$. By analytic continuation of the data with $\mu_I < \pi T/3$ to real values of the chemical potential, we expect at each $\kappa\in [0,\kappa_{chiral}]$, a transition line on the $(\mu, T)$ plane, in a region relevant to the search for quark gluon plasma in heavy-ion collision experiments. The transition is first order at small or large quark mass, and becomes a crossover at intermediate quark mass.Comment: Published versio

Centers and Cocenters of 00-Hecke algebras

In this paper, we give explicit descriptions of the centers and cocenters of $0$-Hecke algebras associated to finite Coxeter groups.Comment: 13 pages, a mistake in 4.2 is correcte

Intrinsic Anomalous Hall Effect in Magneto-Chiral States

We show that a finite Hall effect in zero applied magnetic field occurs for partially filled bands in certain time-reversal violating states with zero net flux per unit-cell. These states are the Magneto-chiral states with parameters in the effective one-particle Hamiltonian such that they do not satisfy the Haldane-type constraints for topological electronic states. The results extend an earlier discussion of the Kerr effect observed in the cuprates but may be applicable to other experimental situations.Comment: published versio

Energy-Conserving Lattice Boltzmann Thermal Model in Two Dimensions

A discrete velocity model is presented for lattice Boltzmann thermal fluid dynamics. This model is implemented and tested in two dimensions with a finite difference scheme. Comparison with analytical solutions shows an excellent agreement even for wide temperature differences. An alternative approximate approach is then presented for traditional lattice transport schemes

Investigation of Partial Discharge in Solid Dielectric under DC Voltage

A partial discharge, or PD, is defined as an electrical discharge that is localized within only a part of the insulation between two separated conductors. Recent research on PD mainly focuses on the study of PD characteristics under AC voltage. Compared with DC, PD under AC is more serious and can be easily detected in terms of PD number. As the results of these concentrated research, the understanding of PD under AC condition has been significantly improved and features extracted from PD measurements have been used to diagnose the insulation condition of many power apparatus. Recently, rapid development in HVDC transmission and power grids connection, and widely applied DC cable and gas-insulated switchgear because of their benefit in long distance usage lead to an increasing concern about PD under DC. However, available study for the condition is little and related research is therefore necessary and essential for understanding the lifetime and reliability of apparatus. <br/

Quark Recombination and Heavy Quark Diffusion in Hot Nuclear Matter

We discuss resonance recombination for quarks and show that it is compatible with quark and hadron distributions in local thermal equilibrium. We then calculate realistic heavy quark phase space distributions in heavy ion collisions using Langevin simulations with non-perturbative T-matrix interactions in hydrodynamic backgrounds. We hadronize the heavy quarks on the critical hypersurface given by hydrodynamics after constructing a criterion for the relative recombination and fragmentation contributions. We discuss the influence of recombination and flow on the resulting heavy meson and single electron R_AA and elliptic flow. We will also comment on the effect of diffusion of open heavy flavor mesons in the hadronic phase.Comment: Contribution to Quark Matter 2011, submitted to J.Phys.G; 4 pages, 5 figure

An age-of-allele test of neutrality for transposable element insertions

How natural selection acts to limit the proliferation of transposable elements (TEs) in genomes has been of interest to evolutionary biologists for many years. To describe TE dynamics in populations, many previous studies have used models of transposition-selection equilibrium that rely on the assumption of a constant rate of transposition. However, since TE invasions are known to happen in bursts through time, this assumption may not be reasonable in natural populations. Here we propose a test of neutrality for TE insertions that does not rely on the assumption of a constant transposition rate. We consider the case of TE insertions that have been ascertained from a single haploid reference genome sequence and have subsequently had their allele frequency estimated in a population sample. By conditioning on the age of an individual TE insertion (using information contained in the number of substitutions that have occurred within the TE sequence since insertion), we determine the probability distribution for the insertion allele frequency in a population sample under neutrality. Taking models of varying population size into account, we then evaluate predictions of our model against allele frequency data from 190 retrotransposon insertions sampled from North American and African populations of Drosophila melanogaster. Using this non-equilibrium model, we are able to explain about 80% of the variance in TE insertion allele frequencies based on age alone. Controlling both for nonequilibrium dynamics of transposition and host demography, we provide evidence for negative selection acting against most TEs as well as for positive selection acting on a small subset of TEs. Our work establishes a new framework for the analysis of the evolutionary forces governing large insertion mutations like TEs, gene duplications or other copy number variants.Comment: 40 pages, 6 figures, Supplemental Data available: [email protected]

(13)C NMR investigation of the superconductor MgCNi_3 up to 800K

We report (13)C NMR characterization of the new superconductor MgCNi_3 (He et al., Nature (411), 54 (2001)). We found that both the uniform spin susceptibility and the spin fluctuations show a strong enhancement with decreasing temperature, and saturate below ~50K and ~20K respectively. The nuclear spin-lattice relaxation rate 1/(13)T_1T exhibits typical behaviour for isotropic s-wave superconductivity with a coherence peak below Tc=7.0K that grows with decreasing magnetic field.Comment: Accepted for publication in Physical Review Letter

Quantum Entanglement of Electromagnetic Fields in Non-inertial Reference Frames

Recently relativistic quantum information has received considerable attention due to its theoretical importance and practical application. Especially, quantum entanglement in non-inertial reference frames has been studied for scalar and Dirac fields. As a further step along this line, we here shall investigate quantum entanglement of electromagnetic fields in non-inertial reference frames. In particular, the entanglement of photon helicity entangled state is extensively analyzed. Interestingly, the resultant logarithmic negativity and mutual information remain the same as those for inertial reference frames, which is completely different from that previously obtained for the particle number entangled state.Comment: more explanatory material added in the introduction, version to appear in Journal of Physics