Thermodynamics for two flavor QCD

We conclude our analysis of the N_t=6 equation of state for two flavor QCD, first described at last year's conference. We have obtained new runs at am_q=0.025 and improved runs at am_q=0.0125. The results are extrapolated to m_q=0, and we extract the speed of sound as well. We also present evidence for a restoration of the SU(2) X SU(2) chiral symmetry just above the crossover, but not of the axial U(1) chiral symmetry.Comment: Poster presented at LATTICE96(finite temperature). 4 pages, LaTeX plus 5 encapsulated Postscript figure

Phenomenological interaction between current quarks

We construct a phenomenological model which describes the dynamical chiral symmetry breaking (DCSB) of QCD vacuum and reproduces meson spectra. Quark condensates, the pion decay constant, and meson spectra are well reproduced by phenomenological interaction which consists of a linear confining potential, a Coulombic potential, and the 't Hooft determinant interaction. In this model, the 't Hooft determinant interaction plays a important role not to only \eta,\eta' mass difference, but other meson masses through DCSB.Comment: 18 pages, LaTe

Chiral transition and monopole percolation in lattice scalar QED with quenched fermions

We study the interplay between topological observables and chiral and Higgs transitions in lattice scalar QED with quenched fermions. Emphasis is put on the chiral transition line and magnetic monopole percolation at strong gauge coupling. We confirm that at infinite gauge coupling the chiral transition is described by mean field exponents. We find a rich and complicated behaviour at the endpoint of the Higgs transition line which hampers a satisfactory analysis of the chiral transition. We study in detail an intermediate coupling, where the data are consistent both with a trivial chiral transition clearly separated from monopole percolation and with a chiral transition coincident with monopole percolation, and characterized by the same critical exponent $\nu \simeq 0.65$. We discuss the relevance (or lack thereof) of these quenched results to our understanding of the \chupiv\ model. We comment on the interplay of magnetic monopoles and fermion dynamics in more general contexts.Comment: 29 pages, 13 figures included, LaTeX2e (elsart

Non-compact Lattice QED with Two Charges: Phase Diagram and Renormalization Group Flow

The phase diagram of non-compact lattice QED in four dimensions with staggered fermions of charges 1 and $-1/2$ is investigated. The renormalized charges are determined and found to be in agreement with perturbation theory. This is an indication that there is no continuum limit with non-vanishing renormalized gauge coupling, and that the theory has a validity bound for every finite value of the renormalized coupling. The renormalization group flow of the charges is investigated and an estimate for the validity bound as a function of the cut-off is obtained. Generalizing this estimate to all fermions in the Standard Model,it is found that a cut-off at the Planck scale implies that $\alpha_R$ has to be less than $1/80$. Due to spontaneous chiral symmetry breaking, strongly bound fermion-antifermion composite states are generated. Their spectrum is discussed.Comment: 35 pages, LATEX, 26 PostScript figures (uuencoded

Presence of Listeria species in fresh meats from retail markets in Serbia

Listeria spp. are Gram positive, short, non-sporing rods, microaerophilic. Of the six species currently recognized, Listeria monocytogenes is the most important as it causes a range of infections in humans and animals. The organism can be found in a wide variety of habitats including the soil, food processing environments and raw foods. The ability of the organism to grow at refrigeration temperatures is of major importance in food production. This study examines the presence of Listeria species in fresh meat. 29 samples (chicken, pork and beef) meat. This bacteria was found in 82.7% of analyzed samples; 7 L. innocua, 8 L. monocytogenes and 9 L. welshimeri (of all isolates). L. innocua prevailed in pork meat (40%), L. monocytogenes in chicken and pork meat (30%), and L. welshimeri in beef meat (44.4%)

Can Sigma Models Describe Finite Temperature Chiral Transitions?

Large-N expansions and computer simulations indicate that the universality class of the finite temperature chiral symmetry restoration transition in the 3D Gross-Neveu model is mean field theory. This is a counterexample to the standard 'sigma model' scenario which predicts the 2D Ising model universality class. We trace the breakdown of the standard scenario (dimensional reduction and universality) to the absence of canonical scalar fields in the model. We point out that our results could be generic for theories with dynamical symmetry breaking, such as Quantum Chromodynamics.Comment: 9 pages, 2 ps figure

Hot Nucleons in Chiral Soliton Models

Chiral lagrangians as effective field theories of QCD are most suitable for the study of nucleons in a hot pion gas because they contain pions and also baryons as solitons of the same action. The semiclassical treatment of the soliton solutions must be augmented by pionic fluctuations which requires renormalisation to 1-loop, and finite temperatures do not introduce new ultraviolet divergencies and may easily be considered. Alternatively, a renormalisation scheme based on the renormalisation group equation at finite temperature comprises and extends the rigorous results of chiral perturbation theory and renders the low energy constants temperature-dependent which allows the construction of temperature-dependent solitons below the critical temperature. The temperature-dependence of the baryon energy and the pion-nucleon coupling is studied. There is no simple scaling law for the temperature-dependence of these quantities.Comment: 17 pages (RevTeX), 5 figure

No elliptic islands for the universal area-preserving map

A renormalization approach has been used in \cite{EKW1} and \cite{EKW2} to prove the existence of a \textit{universal area-preserving map}, a map with hyperbolic orbits of all binary periods. The existence of a horseshoe, with positive Hausdorff dimension, in its domain was demonstrated in \cite{GJ1}. In this paper the coexistence problem is studied, and a computer-aided proof is given that no elliptic islands with period less than 20 exist in the domain. It is also shown that less than 1.5% of the measure of the domain consists of elliptic islands. This is proven by showing that the measure of initial conditions that escape to infinity is at least 98.5% of the measure of the domain, and we conjecture that the escaping set has full measure. This is highly unexpected, since generically it is believed that for conservative systems hyperbolicity and ellipticity coexist

The Three Dimensional Thirring Model for Small N_f

We formulate the three dimensional Thirring model on a spacetime lattice and study it for various even numbers of fermion flavors N_f by Monte Carlo simulation. We find clear evidence for spontaneous chiral symmetry breaking at strong coupling, contradicting the predictions of the 1/N_f expansion. The critical point appears to correspond to an ultra-violet fixed point of the renormalisation group; a fit to a RG-inspired equation of state in the vicinity of the fixed point yields distinct critical exponents for N_f=2 and N_f=4, while no fit is found for N_f=6, suggesting there is a critical number N_fc<6 beyond which no chiral symmetry breaking occurs. The spectrum of the N_f=2 theory is studied; the states examined vary sharply but continuously across the transition.Comment: 50 pages LaTeX, including 16 tables and 20 figures - uses style file ldd_art.sty (included