12 research outputs found
An Analytic Variational Study of the Mass Spectrum in 2+1 Dimensional SU(3) Hamiltonian Lattice Gauge Theory
We calculate the masses of the lowest lying eigenstates of improved SU(2) and
SU(3) lattice gauge theory in 2+1 dimensions using an analytic variational
approach. The ground state is approximated by a one plaquette trial state and
mass gaps are calculated in the symmetric and antisymmetric sectors by
minimising over a suitable basis of rectangular states
Stringent Constraints on Cosmological Neutrino-Antineutrino Asymmetries from Synchronized Flavor Transformation
We assess a mechanism which can transform neutrino-antineutrino asymmetries
between flavors in the early universe, and confirm that such transformation is
unavoidable in the near bi-maximal framework emerging for the neutrino mixing
matrix. We show that the process is a standard Mikheyev-Smirnov-Wolfenstein
flavor transformation dictated by a synchronization of momentum states. We also
show that flavor ``equilibration'' is a special feature of maximal mixing, and
carefully examine new constraints placed on neutrino asymmetries. In
particular, the big bang nucleosynthesis limit on electron neutrino degeneracy
xi_e < 0.04 does not apply directly to all flavors, yet confirmation of the
large-mixing-angle solution to the solar neutrino problem will eliminate the
possibility of degenerate big bang nucleosynthesis.Comment: 11 pages, 6 figures; minor changes to match PRD versio
Oscillation effects on neutrino decoupling in the early universe
In the early universe, neutrinos decouple from equilibrium with the
electromagnetic plasma at a temperature which is only slightly higher than the
temperature where electrons and positrons annihilate. Therefore neutrinos to
some extent share in the entropy transfer from e^+e^- to other species, and
their final temperature is slightly higher than the canonical value T_nu =
(4/11)^{1/3} T_gamma. We study neutrino decoupling in the early universe with
effects of neutrino oscillations included, and find that the change in neutrino
energy density from e^+ e^- annihilations can be about 2-3% higher if
oscillation are included. The primordial helium abundance can be changed by as
much as 1.5 x 10^-4 by neutrino oscillations.Comment: minor changes, matches version to appear in PR
Early Jurassic palaeoenvironments in the Surat Basin, Australia - marine incursion into eastern Gondwana
Interpretations of palaeodepositional environments are important for reconstructing Earth history. Only a few maps showing the Jurassic depositional environments in eastern Australia currently exist. Consequently, a detailed understanding of the setting of Australia in Gondwana is lacking. Core, wireline logs, two‐dimensional and three‐dimensional seismic from the Precipice Sandstone and Evergreen Formation in the Surat Basin have been used to construct maps showing the evolution of depositional environments through the Early Jurassic. The results indicate the succession consists of three third‐order sequences (Sequence 1 to Sequence 3) that were controlled by eustatic sea level. The lowstand systems tract in Sequence 1 comprises braidplain deposits, confined to a fairway that parallels the basin centre. The strata were initially deposited in two sub‐basins, with rivers flowing in different orientations in each sub‐basin. The transgressive systems tract of Sequence 1 to lowstand systems tract of Sequence 3 is dominated by fluvio–deltaic systems infilling a single merged basin centre. Finally, the transgressive and highstand systems tracts of Sequence 3 show nearshore environments depositing sediment into a shallow marine basin. In the youngest part of this interval, ironstone shoals are the most conspicuous facies, the thickness and number of which increase towards the north and east. This study interprets a corridor to the open ocean through the Clarence–Moreton Basin, or the Carpentaria and Papuan basins, evidence of which has been eroded. These results challenge a commonly held view that eastern Australia was not influenced by eustasy, and propose a more dynamic palaeogeographic setting comprising a mixture of fluvial, deltaic and shallow marine sedimentary environments. This work can be used to unravel the stratigraphic relationships between Mesozoic eastern Australian basins, or in other basins globally as an analogue for understanding the complex interplay of paralic depositional systems in data poor areas
Strangeness nuclear physics: a critical review on selected topics
Selected topics in strangeness nuclear physics are critically reviewed. This
includes production, structure and weak decay of --Hypernuclei, the
nuclear interaction and the possible existence of bound
states in nuclei. Perspectives for future studies on these issues are also
outlined.Comment: 63 pages, 51 figures, accepted for publication on European Physical
Journal
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NEUTRINO MASSES OR NEW INTERACTIONS
Recent proposals to study the mass of the electron neutrino at a sensitivity of 0.3 eV can be used to place limits on the right handed and scalar charged currents at a level which improves on the present experimental limits. Indeed the neglect of the possibility of such interactions can load to the inference of an incorrect value for the mass, as they illustrate
Journal of Molecular Spectroscopy
The Journal of Molecular Spectroscopy presents experimental and theoretical articles on all subjects relevant to molecular spectroscopy and its modern applications. An international medium for the publication of some of the most significant research in the field, the Journal of Molecular Spectroscopy is an invaluable resource for astrophysicists, chemists, physicists, engineers, and others involved in molecular spectroscopy research and practice