12086987
Geodesics in Kasner universes.
Recently, Kasner model universes of various dimensionalities have been explored to see if they could be used in the manner of Kaluza-Klein models to provide the additional unobservable dimensions called for in current elementary-particle models. These discussions have focused narrowly on the number of dimensions and the manner in which those dimensions in excess of the observable four of spacetime behave. This paper discusses some features of Kasner models which ultimately should be considered if these models are to provide a useful arena for studying elementary particles. In particular, geodesics are examined in detail. It is found that there may be a limit to the distance traveled by timelike particles, that spacelike geodesics are limited in their temporal extent, and that for null geodesics in expanding directions the coordinate speed approaches zero.
123501567
Bianchi IV metric with electromagnetic field
An exact solution of the Einstein equations with an electromagnetic field source and Bianchi IV symmetry is described. This solution possesses, in the limiting case of vanishing source tensor, a previously discovered vacuum metric.
122505813
Comment on Coleman's theory of gravitation
The similarity of Coleman's theory (see abstr. A66860 of 1971) to a special case of a class of theories presented by Papapetrou (1954) is discussed.
10069365
58Ni+n transmission, differential elastic scattering, and capture measurements and analysis up to 813 keV.
High-resolution neutron cross section measurements for $^{58}\mathrm{enriched}$ targets were made at the Oak Ridge Electron Linear Accelerator of transmission below 20 MeV, of differential elastic scattering from 10 keV to 5 MeV, and of capture from 2.6 keV to 2.5 MeV. The transmission data were analyzed from 0.1 to 813 keV with a multilevel R-matrix code which uses Bayes' theorem for the fitting process. This code provides energies and neutron widths of resonances within the analyzed region, as well as a possible parametrization for resonances external to that region, as a way of describing the smooth cross section over the entire energy range. The differential elastic data at different scattering angles were compared to theoretical calculations from 30 to 813 keV using an R-function code which is based on the Blatt-Biedenharn formalism. Various combinations of spin and parity were tested to predict cross sections for the well-defined lg0 resonances, and comparison with the data then provided spin and parity assignments for most of these resonances.
42736184
Nonrenormalization of the superstring tension.
It is argued that the superstring tension is not renormalized in perturbation theory for vacua which preserve N= 1 spacetime supersymmetry. Some implications of this result for macroscopic superstrings are discussed, as well as some analogies between macroscopic superstrings and solitons in supersymmetric theories.
41263748
Spherical optical model potential for the Re/Os stellar nucleosynthesis chronometer from s-wave neutrons on 186,187,188Os.
26193328
Effects of neutron-star superconductivity on magnetic monopoles and core field decay.
From the magnetic properties of old neutron stars we propose that an observation of a sufficiently old pulsar limits any ``grand unified theory'' heavy magnetic monopole flux in the pulsar neighborhood to below 5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}24}$${\ensuremath{\tau}}_{10}$${}^{\mathrm{\ensuremath{-}}2}$${\mathrm{cm}}^{\mathrm{\ensuremath{-}}}$ $^{2}$${\mathrm{sr}}^{\mathrm{\ensuremath{-}}1}$sec$^{\mathrm{\ensuremath{-}}1}$, where ${\ensuremath{\tau}}_{10}$ is the age (in ${10}^{10}$ yr) of the pulsar's present magnetic field and monopole speeds are \ensuremath{\sim}${10}^{\mathrm{\ensuremath{-}}3}$ c. For the millisecond pulsar PSR 1937+214 a major improvement over the Parker limit is obtained, which is also better than various limits from monopole catalysis of baryon decay, provided ${\ensuremath{\tau}}_{10}$\ensuremath{\gtrsim}${10}^{\mathrm{\ensuremath{-}}1}$. The consideration of monopole dynamics inside superconducting neutron-star cores leads to this conclusion.