Anyons as quon particles

The momentum operator representation of nonrelativistic anyons is developed in the Chern - Simons formulation of fractional statistics. The connection between anyons and the q-deformed bosonic algebra is established.Comment: 10 pages,Late

Planar QED at finite temperature and density: Hall conductivity, Berry's phases and minimal conductivity of graphene

We study 1-loop effects for massless Dirac fields in two spatial dimensions, coupled to homogeneous electromagnetic backgrounds, both at zero and at finite temperature and density. In the case of a purely magnetic field, we analyze the relationship between the invariance of the theory under large gauge transformations, the appearance of Chern-Simons terms and of different Berry's phases. In the case of a purely electric background field, we show that the effective Lagrangian is independent of the chemical potential and of the temperature. More interesting: we show that the minimal conductivity, as predicted by the quantum field theory, is the right multiple of the conductivity quantum and is, thus, consistent with the value measured for graphene, with no extra factor of pi in the denominator.Comment: 27 pages, no figures. Minor misprints corrected. Final version, to appear in J. Phys. A: Math. Ge

Gauge symmetry and the EMC spin effect

We emphasise the EMC spin effect as a problem of symmetry and discuss the renormalisation of the $C=+1$ axial tensor operators. This involves the generalisation of the Adler-Bell-Jackiw anomaly to each of these operators. We find that the contribution of the axial anomaly to the spin dependent structure function $g_1 (x, Q^2)$ scales at $O(\alpha_s)$. This means that the anomaly can be a large $x$ effect in $g_1$. Finally we discuss the jet signature of the anomaly.Comment: 17 pages, Latex, Cavendish preprint HEP 93/

Unrestricted Hartree-Fock Analysis of Sr3−x_{3-x}Cax_xRu2_2O7_7

We investigated the electronic and magnetic structure of Sr$_{3-x}$Ca$_x$Ru$_2$O$_7$ ($0 \leq x \leq 3$) on the basis of the double-layered three-dimensional multiband Hubbard model with spin-orbit interaction. In our model, lattice distortion is implemented as the modulation of transfer integrals or a crystal field. The most stable states are estimated within the unrestricted Hartree-Fock approximation, in which the colinear spin configurations with five different spin-quantization axes are adopted as candidates. The obtained spin structures for some particular lattice distortions are consistent with the neutron diffraction results for Ca$_3$Ru$_2$O$_7$. Also, some magnetic phase transitions can occur due to changes in lattice distortion. These results facilitate the comprehensive understanding of the phase diagram of Sr$_{3-x}$Ca$_x$Ru$_2$O$_7$.Comment: 16 pages, 7 figure

Tachyonization of the \LaCDM cosmological model

In this work a tachyonization of the $\Lambda$CDM model for a spatially flat Friedmann-Robertson-Walker space-time is proposed. A tachyon field and a cosmological constant are considered as the sources of the gravitational field. Starting from a stability analysis and from the exact solutions for a standard tachyon field driven by a given potential, the search for a large set of cosmological models which contain the $\Lambda$CDM model is investigated. By the use of internal transformations two new kinds of tachyon fields are derived from the standard tachyon field, namely, a complementary and a phantom tachyon fields. Numerical solutions for the three kinds of tachyon fields are determined and it is shown that the standard and complementary tachyon fields reproduces the $\Lambda$CDM model as a limiting case. The standard tachyon field can also describe a transition from an accelerated to a decelerated regime, behaving as an inflaton field at early times and as a matter field at late times. The complementary tachyon field always behaves as a matter field. The phantom tachyon field is characterized by a rapid expansion where its energy density increases with time.Comment: Version accepted for publication in GR

Some recent rural radio talks

Current experiments with vegetable crops - By T. WACHTEL, Agricultural Adviser, Horticultural Division Pedigree seed planting - By H. G. CARISS, B.Sc. (Agric), Regional Agricultural Adviser The Ruakura round farrowing house - By P. BECK, Field Assistant, Dairying Division How the random sample laying test could affect the poultry industry - By R. H. MORRIS, Officer-in-Charge, Poultry Branch Feeding the milking goat - By K. NEEDHAM, Dairy Cattle Husbandry Officer Fertilisers for vegetables in summer months - By J. P. FALLON, Senior Adviser (Vegetables), Horticultural Division Pastures and their carrying capacity - By H. G. ELLIOTT, Assistant Superintendent of Dairying Pollination - By J. CRIPPS, Adviser, Horticultural Division Aeroplanes and insect pest control - By P. N. FORTE, Senior Entomologist Kill those flies - By H. MASLIN, Dairy Instructor, Busselton Grazing for pigs - By P. BECK, Field Assistant, Dairying Division Feed flavours in cream - By an officer of the Dairying Division. Those old milk and cream cans - By D. C. MICKLE, Dairy Instructor, Bunbury Overrun in butter making and quality in home-made butter - By A. H. HOBBS, Dairy Produce Inspector Milk flow indicators - By G. W. SCOTT, Dairy Instructor, Head Offic

Galaxy populations in the Antlia cluster. I. Photometric properties of early-type galaxies

We present the first colour-magnitude relation (CMR) of early-type galaxies in the central region of the Antlia cluster, obtained from CCD wide-field photometry in the Washington photometric system. Integrated (C -T1) colours, T1 magnitudes, and effective radii have been measured for 93 galaxies (i.e. the largest galaxies sample in the Washington system till now) from the FS90 catalogue (Ferguson & Sandage 1990). Membership of 37 objects can be confirmed through new radial velocities and data collected from the literature. The resulting colour-magnitude diagram shows that early-type FS90 galaxies that are spectroscopically confirmed Antlia members or that were considered as definite members by FS90, follow a well defined CMR (sigma_(C -T1) ~ 0.07 mag) that spans 9 magnitudes in brightness with no apparent change of slope. This relation is very tight for the whole magnitude range but S0 galaxies show a larger dispersion, apparently due to a separation of ellipticals and S0s. Antlia displays a slope of -13.6 in a T1 vs. (C -T1) diagram, in agreement with results for clusters like Fornax, Virgo, Perseus and Coma, which are dynamically different to Antlia. This fact might indicate that the build up of the CMR in cluster of galaxies is more related to galaxies internal processes than to the influence of the environment. Interpreting the CMR as a luminosity-metallicity relation of old stellar systems, the metallicities of the Antlia galaxies define a global relation down to Mv ~ -13. We also find, for early-type dwarfs, no clear relation between luminosity and effective radius, indicating a nearly constant mean effective radius of ~ 1 kpc. This value is also found in several samples of dwarf galaxies in Virgo and Coma.Comment: 13 pages, 6 figures. Accepted for publication in MNRA

Hyperon Polarization in the Constituent Quark Model

We consider mechanism for hyperon polarization in inclusive production. The main role belongs to the orbital angular momentum and polarization of the strange quark-antiquark pairs in the internal structure of the constituent quarks. We consider a nucleon as a core consisting of the constituent quarks embedded into quark condensate. The nonperturbative hadron structure is based on the results of chiral quark models.Comment: 14 pages, LaTeX, 2 Figures, References adde

Gauge Invariance, Finite Temperature and Parity Anomaly in D=3

The effective gauge field actions generated by charged fermions in $QED_3$ and $QCD_3$ can be made invariant under both small and large gauge transformations at any temperature by suitable regularization of the Dirac operator determinant, at the price of parity anomalies. We resolve the paradox that the perturbative expansion is not invariant, as manifested by the temperature dependence of the induced Chern-Simons term, by showing that large (unlike small) transformations and hence their Ward identities, are not perturbative order-preserving. Our results are illustrated through concrete examples of field configurations.Comment: 4 pages, RevTe