Supersymmetry algebra cohomology III: Primitive elements in four and five dimensions

The primitive elements of the supersymmetry algebra cohomology as defined in a previous paper are computed for standard supersymmetry algebras in four and five dimensions, for all signatures of the metric and any number of supersymmetries.Comment: v2: D=4 analysis simplified, D=5 analysis added, refs. added, typos corrected, 32 page

Supersymmetry algebra cohomology I: Definition and general structure

The paper concerns standard supersymmetry algebras in diverse dimensions, involving bosonic translational generators and fermionic supersymmetry generators. A cohomology related to these supersymmetry algebras, termed supersymmetry algebra cohomology, and corresponding "primitive elements" are defined by means of a BRST-type coboundary operator. A method to systematically compute this cohomology is outlined and illustrated by simple examples.Comment: v5: matches published version; 3 refs., section 5.5 and remarks/comments in sections 1, 2.8, 3 and 7 added; minor editorial improvements and change of titl

Resonant electronic Raman scattering near a quantum critical point

We calculate the resonant electronic Raman scattering for the Falicov-Kimball model near the Mott transition on a hypercubic lattice. The solution is exact, and employs dynamical mean field theory.Comment: 2 pages, 2 figures, contribution to the SCES04 conferenc

Top quark mass measurements at the Tevatron

The latest measurements of the top quark mass in various decay channels of top quark pair production are presented. A brief introduction to the measurement techniques is given. The measurements are performed on data samples of up to 4.8 fb−1 of integrated luminosity acquired by the CDF and DØ experiments in Run II of the Tevatron p¯p collider at a centre-of-mass energy of √s = 1.96TeV. The Tevatron combination using up to 5.6 fb−1 of data results in a preliminary world average top quark mass of mtop = 173.3 ± 1.1GeV. This corresponds to a relative precision of about 0.6%

The theory of the reentrant effect in susceptibility of cylindrical mesoscopic samples

A theory has been developed to explain the anomalous behavior of the magnetic susceptibility of a normal metal-superconductor ($NS$) structure in weak magnetic fields at millikelvin temperatures. The effect was discovered experimentally by A.C. Mota et al \cite{10}. In cylindrical superconducting samples covered with a thin normal pure metal layer, the susceptibility exhibited a reentrant effect: it started to increase unexpectedly when the temperature lowered below 100 mK. The effect was observed in mesoscopic $NS$ structures when the $N$ and $S$ metals were in good electric contact. The theory proposed is essentially based on the properties of the Andreev levels in the normal metal. When the magnetic field (or temperature) changes, each of the Andreev levels coincides from time to time with the chemical potential of the metal. As a result, the state of the $NS$ structure experiences strong degeneracy, and the quasiparticle density of states exhibits resonance spikes. This generates a large paramagnetic contribution to the susceptibility, which adds up to the diamagnetic contribution thus leading to the reentrant effect. The explanation proposed was obtained within the model of free electrons. The theory provides a good description for experimental results [10]

Distribution and composition of macrobenthic communities along a Victoria-Land Transect (Ross Sea, Antarctica)

The Victoria-Land Transect project onboard the Italian research vessel ‘‘Italica’’ in February 2004, was a large-scale attempt to obtain benthic samples of smaller macrozoobenthic specimens systematically along a latitudinal and a depth transect along the Victoria- Land coast. Data presented from this survey are based on Rauschert dredge samples, which were taken at four areas at depth ranging from 84 to 515 m. A cluster analysis based on relative numbers of abundance was performed and demonstrated a change in community structure depending on the location along the latitudinal transect. A change in community structure with depth was not recorded. Dominant taxa of the Ross Sea fauna along the Victoria-Land coast were the Arthropoda (65.7%), followed by Annelida (20.7%), Mollusca (9.6%) and Echinodermata (2.5%). Total number of abundance decreased with depth with an exception at Cape Russell, whereas a trend in biomass was not documented. Abundance and biomass proportions of major taxa changed gradually along the latitudinal transect