Decuplet Baryon Magnetic Moments in the Chiral Quark Model

We present calculations of the decuplet baryon magnetic moments in the chiral quark model. As input we use parameters obtained in qualitatively accurate fits to the octet baryon magnetic moments studied previously. The values found for the magnetic moments of $\Delta^{++}$ and $\Omega^{-}$ are in good agreement with experiments. We finally calculate the total quark spin polarizations of the decuplet baryons and find that they are considerably smaller than what is expected from the non-relativistic quark model

Hard X-ray detection of the high redshift quasar 4C 71.07

BATSE/OSSE observations of the high redshift quasar 4C 71.07 indicate that this is the brightest and furthest AGN so far detected above 20 keV. BATSE Earth occultation data have been used to search for emission from 4C 71.07 from nearly 3 years of observation. The mean source flux over the whole period in the BATSE energy range 20-100 keV is (13.2 +/- 1.06) x 10^(-11) erg cm^(-2) s^(-1) corresponding to a luminosity of 2 x 10^(48) erg s^(-1). The BATSE light curve over the 3 years of observations shows several flare-like events, one of which (in January 1996) is associated with an optical flare (R=16.1) but with a delay of 55 days. The OSSE/BATSE spectral analysis indicates that the source is characterized by a flat power spectrum (Gamma about 1.1 - 1.3) when in a low state; this spectral form is consistent within errors with the ASCA and ROSAT spectra. This means that the power law observed from 0.1 to 10 keV extends up to at least 1 MeV but steepens soon after to meet EGRET high energy data. BATSE data taken around the January 1996 flare suggests that the spectrum could be steeper when the source is in a bright state. The nuF-nu representation of the source is typical of a low frequency peaked/gamma-ray dominated blazar, with the synchrotron peak in the mm-FIR band and the Compton peak in the MeV band. The BATSE and OSSE spectral data seem to favour a model in which the high energy flux is due to the sum of the synchrotron self-Compton and the external Compton contributions; this is also supported by the variability behaviour of the source.Comment: 19 pages, LaTeX, plus 4 .ps figures. accepted by Astrophysical Journa

Genome Symbols in the Triticeae (Poaceae)

A system for the application of nuclear genome symbols in the tribe Triticeae is proposed. It is based mainly on prevailing symbols. In agreement with this, the system uses individual upper case letters as symbols in the first place. Since the number of basic nuclear genomes in the Triticeae exceeds the number of single letters in the Roman alphabet, some basic genomes are designated with an upper case letter followed by a lower case letter, e.g. Ns for the genome of Psathyrostachys. Superscripts in small letters are used when modified versions of a basic genome are referred to, e.g. HP for the genome found in Hordeum pusillum. Unknown or equivocally identified genomes are designated by X followed by a lower case letter, e.g. Xu for Hordeum murinum. Underline of the relevant genome symbol can be used to indicate the origin of the cytoplasm

Pseudonatural Inflation

We study how to obtain a sufficiently flat inflaton potential that is natural from the particle physics point of view. Supersymmetry, which is broken during inflation, cannot protect the potential against non-renormalizable operators violating slow-roll. We are therefore led to consider models based on non-linearly realized symmetries. The basic scenario with a single four-dimensional pseudo Nambu Goldstone boson requires the spontaneous breaking scale to be above the Planck scale, which is beyond the range of validity of the field theory description, so that quantum gravity corrections are not under control. A nice way to obtain consistent models with large field values is to consider simple extensions in extra-dimensional setups. We also consider the minimal structures necessary to obtain purely four-dimensional models with spontaneous breaking scale below M_P; we show that they require an approximate symmetry that is supplemented by either the little-Higgs mechanism or supersymmetry to give trustworthy scenarios.Comment: 30 pages, 2 figures. v2: minor changes, ref. added, accepted for JCA

The Growth of Bubbles in Cosmological Phase Transitions

We study how bubbles grow after the initial nucleation event in generic first-order cosmological phase transitions characterised by the values of latent heat, interface tension and correlation length, and driven by a scalar order parameter $\phi$. Equations coupling $\phi$ and the fluid variables $v$ and $T$ and depending on a dissipative constant $\Gamma$ are derived and solved numerically in the 1+1 dimensional case starting from a slightly deformed critical bubble configuration. Parameters corresponding to QCD and electroweak phase transitions are chosen and the whole history of the bubble with formation of combustion and shock fronts is computed as a function of $\Gamma$. Both deflagrations and detonations can appear depending on the values of the parameters. Reheating due to collisions of bubbles is also computed.Comment: 24 LaTeX-pages with 20 figures not included. The complete PostScript file, including figures, is available by anonymous ftp from fltxc.helsinki.fi, as /pub/bubble.ps, or as a hardcopy by airmail (a dublicate lies at nic.funet.fi:/pub/sci/physics/papers/bubble.ps). Helsinki Preprint HU-TFT-93-4