Genetic Algorithm for SU(2) Gauge Theory on a 2-dimensional Lattice

An algorithm is proposed for the simulation of pure SU(N) lattice gauge theories based on Genetic Algorithms(GAs). We apply GAs to SU(2) pure gauge theory on a 2 dimensional lattice and show the results, the action per plaquette and Wilson loops, are consistent with those by Metropolis method(MP)s and Heatbath method(HB)s. Thermalization speed of GAs is especially faster than the simple MPs.Comment: 3 pages,9 figures,LATTICE98(Algorithm), "Genetic Algorithm for SU(N) Gauge Theory on a Lattice

Spaces of polynomials with roots of bounded multiplicity

We describe an alternative approach to some results of Vassiliev on spaces of polynomials, by using the scanning method which was used by Segal in his investigation of spaces of rational functions. We explain how these two approaches are related by the Smale-Hirsch Principle or the h-Principle of Gromov. We obtain several generalizations, which may be of interest in their own right.Comment: 29 pages, AMS-Te

Black Strings in Our World

The brane world scenario is a new approach to resolve the problem on how to compactify the higher dimensional spacetime to our 4-dimensional world. One of the remarkable features of this scenario is the higher dimensional effects in classical gravitational interactions at short distances. Due to this feature, there are black string solutions in our 4-dimensional world. In this paper, assuming the simplest model of complex minimally coupled scalar field with the local U(1) symmetry, we show a possibility of black-string formation by merging processes of type I long cosmic strings in our 4-dimensional world. No fine tuning for the parameters in the model might be necessary.Comment: 11pages, no figur

Integration of visual stimuli by the crayfish central nervous system

For the crayfish, properties of visually reacting interneurone types in the optic nerve are described on the basis of single-unit analysis. Sustaining fibres show: (a) ‘surround’ inhibition over the whole retina, including the excitatory field; (b) ‘on’ and ‘off’ effects at field boundaries; (c) a dark discharge in deteriorated preparations; (d) an increase in adapted firing rate and response to flashes in an ‘excited state’ of the preparation; (e) increased overall impulse frequency to fast-moving shadows at frequencies of 2-10/sec. which elicit short bursts. Dimming fibres, having mainly reversed properties, show: (a) bursts followed by adaptation to a lower ferquency level of spikes on light dimming; (b) total inhibition by illumination for times proportional to light intensity; (c) responsiveness to quickly moving shadows. 'Jittery’ movement fibres lack directional sensitivity. For them: (a) total illumination and contrast have, within a wide range, no effect on discharges to moving targets; (b) large, dark cards moved at constant speed are seen only near their visual field boundary; (c) the less predictable the movement of a small dark object is, the longer its excitatory effect lasts; (d) responsiveness of field parts exposed is decreased for long durations; (e) no firing is caused by active or passive eye motions. Space-constant fibres show changed location and size of their excitatory fields with eye position. Their potential visual fields below the horizontal plane are unresponsive, due to inhibition caused mainly by statocyst input. Two eye muscle motor fibres, also under statocyst control, are influenced by light on the limited sensory fields of two pairs of identifiable sustaining fibres. The two motor fibres, which innervate antagonistic muscles, are reversely excited and inhibited by these fields

Cosmological evolution of cosmic strings with time-dependent tension

We discuss the cosmological evolution of cosmic strings with time-dependent tension. We show that, in the case that the tension changes as a power of time, the cosmic string network obeys the scaling solution: the characteristic scale of the string network grows with the time. But due to the time dependence of the tension, the ratio of the energy density of infinite strings to that of the background universe is {\it not} necessarily constant.Comment: 9 pages, to appear in Phys. Rev.

Creep rupture of materials: insights from a fiber bundle model with relaxation

I adapted a model recently introduced in the context of seismic phenomena, to study creep rupture of materials. It consists of linear elastic fibers that interact in an equal load sharing scheme, complemented with a local viscoelastic relaxation mechanism. The model correctly describes the three stages of the creep process, namely an initial Andrade regime of creep relaxation, an intermediate regime of rather constant creep rate, and a tertiary regime of accelerated creep towards final failure of the sample. In the tertiary regime creep rate follows the experimentally observed one over time-to-failure dependence. The time of minimum strain rate is systematically observed to be about 60-65 % of the time to failure, in accordance with experimental observations. In addition, burst size statistics of breaking events display a -3/2 power law for events close to the time of failure, and a steeper decay for the all-time distribution. Statistics of interevent times shows a tendency of the events to cluster temporarily. This behavior should be observable in acoustic emission experiments

D-term chaotic inflation in supergravity

Even though the chaotic inflation is one of the most popular inflation models for its simple dynamics and compelling resolutions to the initial condition problems, its realization in supergravity has been considered a challenging task. We discuss how the chaotic inflation dominated by the D-term can be induced in supergravity, which would give a new perspective on the inflation model building in supergravity.Comment: 5 pages, to appear in Phys. Rev.

Parity violating observables in radiative neutrino pair emission from metastable atoms

We report on a possibility of measuring parity violating effects in radiative neutrino pair emission from metastable atoms; asymmetric angular distribution of emitted photons from oriented atoms and emergent circular polarization. Their observation, along with the continuous photon energy spectrum which has 6 thresholds, may be interpreted as events being a combined weak and QED process, emission of $\gamma \nu_i \nu_j$ in the final state. The method may greatly help to perform neutrino mass spectroscopy using atoms, a systematic determination of the neutrino mass matrix.Comment: 9 pages, 4 figure