118865781
Meson correlators above deconfinement
We review recent progress in studying spectral functions for mesonic observables at finite temperatures, by analysis of imaginary time correlators directly calculated on isotropic lattices. Special attention is paid to the lattice artefacts present in such calculations.
16483183
MESON CORRELATION FUNCTIONS AT HIGH TEMPERATURES.
We present preliminary results for the correlation- and spectral functions of different meson channels on the lattice. The main focus lies on gaining control over cut-off as well as on the finite-volume effects. Extrapolations of screening masses above the deconfining temperature are guided by the result of the free (T = {infinity}) case on the lattice and in the continuum. We study the quenched non-perturbatively improved Wilson-clover fermion as well as the hypercube fermion action which might show less cut-off effects.
15925176
A Possible Lack of Phase Transition in SO(3) Lattice Gauge Theory on Lattices with Two Temporal Sites
This paper is being withdrawn as its main results are already included in section 2 of the paper hep-lat/9901006.
1721697
Hadron correlators, spectral functions and thermal dilepton rates from lattice QCD
We discuss information on thermal modifications of hadron properties which can be extracted from the structure of Euclidean correlation functions of hadronic currents as well as more direct information obtained through the reconstruction of the spectral functions based on the Maximum Entropy Method.
119435829
Behavior of charmonium systems after deconfinement
We present a study of charmonia in hot gluonic plasma, for temperatures up to three times the deconfinement transition temperature ${T}_{c}.$ $q\overline{q}$ systems with quark masses close to the charm mass and different spin-parity quantum numbers were studied on very fine isotropic lattices. The analysis of temporal correlators, and spectral functions constructed from them, shows that the $J/\ensuremath{\psi}$ and ${\ensuremath{\eta}}_{c}$ survive up to quite high temperatures, with little observable change up to ${1.5T}_{c},$ and then gradually weaken and disappear by ${3T}_{c}.$ For the scalar and axial vector channels, serious modifications are induced by the hot medium already close to ${T}_{c},$ possibly dissociating the mesons by ${1.1T}_{c}.$
119240200
Properties of the SU(Nc) Gluon Plasma
We investigate the deconfinement transition in SU(Nc) gauge theories, and properties of the deconfined phase. A detailed lattice study of SU(4) and SU(6) gauge theories are conducted, and finite volume and cutoff effects on thermodynamic observables are studied. The scaling of the deconfinement transition point with lattice spacing is used to calculate the scale, Lambda_MSbar. The continuum estimates of the thermodynamic quantities are used to study properties of the gluon plasma. In particular, the approach to conformal limit is studied. We do not find any evidence of a strongly coupled, conformal phase in these theories.
119521185
Colors of Luminous Bulges in Cluster MS 1054–03 and Field Galaxies at Redshifts z ~ 0.83*
Using Hubble Space Telescope images, we separate the bulgelike (dubbed "pbulge") and disklike ("pdisk") components of 71 galaxies in the rich cluster MS 1054-03 and of 21 in the field. Our key finding is that luminous pbulges are very red, with rest-frame U-B ~ 0.45, while predicted colors are bluer by 0.20 mag. Moreover, these very red colors appear to be independent of environment, pbulge luminosity, pdisk color, and pbulge fraction. These results challenge any model of hierarchical galaxy formation that predicts the colors of distant (z ~ 0.8) luminous field and cluster bulges will differ. Our findings also disagree with other claims that 30% to 50% of bright bulges and elliptical galaxies at z ~ 1 are very blue (U-B ≤ 0).
18570338
Fractal Structure of Molecular Clouds
Compelling evidence exists to show that the structure of molecular clouds is fractal in nature. In this paper, the author reiterates this view and, in addition, asserts that not only is cloud geometry fractal, but that they also have a common characteristic - they are similar in shape to the Horsehead nebula in Orion. This shape can be described by the Julia function f(x)= z^2 + c,where both z and c are complex quantities and c = -0.745429 + 0.113008i. The dynamical processes responsible for the production of these clouds seem to be turbulence followed by Brownian motion till high densities are reached, at which point structure formation is dictated by gravity. The author presents image analysis of four varied examples, namely those of the Horsehead nebula, Eagle nebula, Rosette nebula and Paley I nebula to prove her hypothesis. The images of these nebulae are analyzed for their box dimension using fractal analysis software and comparisons are made with the given Julia set.