Temperature, chemical potential and the rho meson

We describe some applications of the Dyson-Schwinger equations at nonzero-(T,mu). Employing a simple model dressed-gluon propagator we determine the boundary of the deconfinement phase transition and the medium dependence of rho-meson properties. We introduce an extension to describe the time-evolution of scalar and vector self energies.Comment: 6 pages, LaTeX with 3 EPS figures; Contribution to the 'International Workshop XXVIII on Gross Properties of Nuclei and Nuclear Excitations', Hirschegg, Austria, 16-22.01.200

Thermonuclear explosions of rapidly rotating white dwarfs - I. Deflagrations

Context: Turbulent deflagrations of Chandrasekhar mass White Dwarfs are commonly used to model Type Ia Supernova explosions. In this context, rapid rotation of the progenitor star is plausible but has so far been neglected. Aims: The aim of this work is to explore the influence of rapid rotation on the deflagration scenario. Methods: We use three dimensional hydrodynamical simulations to model turbulent deflagrations ignited within a variety of rapidly rotating CO WDs obeying rotation laws suggested by accretion studies. Results: We find that rotation has a significant impact on the explosion. The flame develops a strong anisotropy with a preferred direction towards the stellar poles, leaving great amounts of unburnt matter along the equatorial plane. Conclusions: The large amount of unburnt matter is contrary to observed spectral features of SNe Ia. Thus, rapid rotation of the progenitor star and the deflagration scenario are incompatible in order to explain SNe Ia.Comment: 13 pages, 10 figures, accepted for publication by A&

On Superalgebras of Matrices with Symmetry Properties

It is known that semi-magic square matrices form a 2-graded algebra or superalgebra with the even and odd subspaces under centre-point reflection symmetry as the two components. We show that other symmetries which have been studied for square matrices give rise to similar superalgebra structures, pointing to novel symmetry types in their complementary parts. In particular, this provides a unifying framework for the composite `most perfect square' symmetry and the related class of `reversible squares'; moreover, the semi-magic square algebra is identified as part of a 2-gradation of the general square matrix algebra. We derive explicit representation formulae for matrices of all symmetry types considered, which can be used to construct all such matrices.Comment: 25 page

DSE Hadron Phenomenology

A perspective on the contemporary use of Dyson-Schwinger equations, focusing on some recent phenomenological applications: a description and unification of light-meson observables using a one-parameter model of the effective quark-quark interaction, and studies of leptonic and nonleptonic nucleon form factors.Comment: 7 pages, sprocl.sty, epsfig.sty. Contribution to the Proceedings of the Workshop on Light-Cone QCD and Nonperturbative Hadron Physics, Adelaide, Australia, 13-22 Dec 199

Non-Gaussian fluctuations near the QCD critical point

We study the effect of the QCD critical point on non-Gaussian moments (cumulants) of fluctuations of experimental observables in heavy-ion collisions. We find that these moments are very sensitive to the proximity of the critical point, as measured by the magnitude of the correlation length xi. For example, the cubic central moment of multiplicity ~ xi^4.5 and the quartic cumulant ~ xi^7. We estimate the magnitude of critical point contributions to non-Gaussian fluctuations of pion and proton multiplicities.Comment: 4 pages, 3 figure

The Character of Goldstone Bosons

A succinct review of the QCD gap equation and dynamical chiral symmetry breaking; their connection with Bethe-Salpeter equations and resolving the dichotomous nature of the pion; the calculation of the pion's valence-quark distribution; and first results for the pi-exchange contribution to the gamma N -> omega N cross-section, which is important in the search for missing nucleon resonances.Comment: 9 pages, LaTeX2e, ws-p8-50x6-00.cls, Contribution to the Proceedings of the "Workshop on Lepton-Scattering, Hadrons and QCD," Adelaide, 26 March-6 April, 200

Thermonuclear explosions of rapidly rotating white dwarfs - II. Detonations

Context: Superluminous type Ia supernovae (SNe Ia) may be explained by super-Chandrasekhar-mass explosions of rapidly rotating white dwarfs (WDs). In a preceding paper, we showed that the deflagration scenario applied to rapidly rotating WDs generates explosions that cannot explain the majority of SNe Ia. Aims: Rotation of the progenitor star allows super-Chandrasekhar-mass WDs to form that have a shallower density stratification. We use simple estimates of the production of intermediate and iron group elements in pure detonations of rapidly rotating WDs to assess their viability in explaining rare SNe Ia. Methods: We numerically construct WDs in hydrostatic equilibrium that rotate according to a variety of rotation laws. The explosion products are estimated by considering the density stratification and by evaluating the result of hydrodynamics simulations. Results: We show that a significant amount of intermediate mass elements is produced for theoretically motivated rotation laws, even for prompt detonations of WDs. Conclusions: Rapidly rotating WDs that detonate may provide an explanation of rare superluminous SNe Ia in terms of both burning species and explosion kinematics.Comment: 7 pages, 5 figures, accepted for publication by A&