12,180 research outputs found
Phase structure and monopoles in U(1) gauge theory
We investigate the phase structure of pure compact U(1) lattice gauge theory
in 4 dimensions with the Wilson action supplemented by a monopole term. To
overcome the suppression of transitions between the phases in the simulations
we make the monopole coupling a dynamical variable. We determine the phase
diagram and find that the strength of the first order transition decreases with
increasing weight of the monopole term, the transition thus ultimately getting
of second order. After outlining the appropriate topological characterization
of networks of currents lines, we present an analysis of the occurring monopole
currents which shows that the phases are related to topological properties.Comment: 22 pages (latex), 14 figures (available upon request), BU-HEP 94-
Ancient Near Eastern Fibers and the Reshaping of European Clothing
In April of 1994, an amazing story hit the news-stands. A group of naturally mummified corpses dated to 2000 BC and later had been found in Chinese Turkestan. Not only were their Caucasian features and blondish hair well preserved by the dry heat of the xinjiang desert, but also their clothes--brightly colored plaids and twills among them (Hadingham 1994). We know from later linguistic records that a group of Indo-European speakers we call the Tocharians had made their way to Xinjiang and the Tarim Basin in early times. We also know that the Indo-Europeans began to spread across Eurasia from somewhere in the Caucasus region during the mid to late third millennium BC. Thus I was delighted to learn eventually that the plaids and twills were of wool, for I had been tracking the origins of twill weave for many years and had concluded that it began with the advent of wool from Mesopotamia into the Caucasus and southeast Europe in the 3rd or late 4th millennium BC (Barber 1990). If these were indeed the Tocharians, then this theory must be right on target.
It is well documented by now that the arrival of a useful new fiber will radically alter the textile technology of a culture. So we see it in early China, with the addition of silk to the older tradition of spinning and weaving hemp (Becker 1987, 81 et passim), and so we see it in early Europe, with the addition of wool to the earlier knowledge of working flax. In Europe, moreover, the addition of wool altered the culture\u27s views not just of how to produce cloth, but also of how cloth could be used
Research and development of high-performance light-weight fuel cell electrodes final report, nov. 1, 1963 - oct. 31, 1964
High performance light weight fuel cell electrode developmen
Specific heat of the simple-cubic Ising model
We provide an expression quantitatively describing the specific heat of the
Ising model on the simple-cubic lattice in the critical region. This expression
is based on finite-size scaling of numerical results obtained by means of a
Monte Carlo method. It agrees satisfactorily with series expansions and with a
set of experimental results. Our results include a determination of the
universal amplitude ratio of the specific-heat divergences at both sides of the
critical point.Comment: 20 pages, 3 figure
Quasiperiodic spin-orbit motion and spin tunes in storage rings
We present an in-depth analysis of the concept of spin precession frequency
for integrable orbital motion in storage rings. Spin motion on the periodic
closed orbit of a storage ring can be analyzed in terms of the Floquet theorem
for equations of motion with periodic parameters and a spin precession
frequency emerges in a Floquet exponent as an additional frequency of the
system. To define a spin precession frequency on nonperiodic synchro-betatron
orbits we exploit the important concept of quasiperiodicity. This allows a
generalization of the Floquet theorem so that a spin precession frequency can
be defined in this case too. This frequency appears in a Floquet-like exponent
as an additional frequency in the system in analogy with the case of motion on
the closed orbit. These circumstances lead naturally to the definition of the
uniform precession rate and a definition of spin tune. A spin tune is a uniform
precession rate obtained when certain conditions are fulfilled. Having defined
spin tune we define spin-orbit resonance on synchro--betatron orbits and
examine its consequences. We give conditions for the existence of uniform
precession rates and spin tunes (e.g. where small divisors are controlled by
applying a Diophantine condition) and illustrate the various aspects of our
description with several examples. The formalism also suggests the use of
spectral analysis to ``measure'' spin tune during computer simulations of spin
motion on synchro-betatron orbits.Comment: 62 pages, 1 figure. A slight extension of the published versio
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