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