Equilibrium and off-equilibrium simulations of chiral-glass order in three-dimensional Heisenberg spin glasses

Spin-glass and chiral-glass orderings in three-dimensional Heisenberg spin glasses are studied both by equilibrium and off-equilibrium Monte Carlo simulations. Fully isotropic model is found to exhibit a finite-temperature chiral-glass transition without the conventional spin-glass order. Although chirality is an Ising-like quantity from symmetry, universality class of the chiral-glass transition appears to be different from that of the standard Ising spin glass. In the off-equilibrium simulation, while the spin autocorrelation exhibits only an interrupted aging, the chirality autocorrelation persists to exhibit a pronounced aging effect reminisecnt of the one observed in the mean-field model. Effects of random magnetic anisotropy is also studied by the off-equilibrium simulation, in which asymptotic mixing of the spin and the chirality is observed.Comment: 15 pages including 8 figures, plain Tex, to appear in Computer Simulation Studies in Condensed Matter Physics XI, Springer, 199

Generalized Heisenberg's Dynamics

We formulate a dynamical system based on many-index objects. These objects yield a generalization of the Heisenberg's equation. Systems describing harmonic oscillators are given.Comment: PTPTEX, 8 page

Quantum Mechanics for the Swimming of Micro-Organism in Two Dimensions

In two dimensional fluid, there are only two classes of swimming ways of micro-organisms, {\it i.e.}, ciliated and flagellated motions. Towards understanding of this fact, we analyze the swimming problem by using $w_{1+\infty}$ and/or $W_{1+\infty}$ algebras. In the study of the relationship between these two algebras, there appear the wave functions expressing the shape of micro-organisms. In order to construct the well-defined quantum mechanics based on $W_{1+\infty}$ algebra and the wave functions, essentially only two different kinds of the definitions are allowed on the hermitian conjugate and the inner products of the wave functions. These two definitions are related with the shapes of ciliates and flagellates. The formulation proposed in this paper using $W_{1+\infty}$ algebra and the wave functions is the quantum mechanics of the fluid dynamics where the stream function plays the role of the Hamiltonian. We also consider the area-preserving algebras which arise in the swimming problem of micro-organisms in the two dimensional fluid. These algebras are larger than the usual $w_{1+\infty}$ and $W_{1+\infty}$ algebras. We give a free field representation of this extended $W_{1+\infty}$ algebra.Comment: OCHA-PP-48, NDA-FP-16, Latex file, 15p

Confidence and Competence in Communication

This paper studies information transmission between an uninformed decision maker (receiver) and an informed player (sender) who have asymmetric beliefs ("confidence") on the sender’s ability ("competence") to observe the state of nature. We find that an overconfident sender’s message is more accurate when his information closer to the prior expectation, whereas an underconfident sender’s message is more accurate when his information is further away from the prior. Moreover, an underconfident sender may prefer to stay out of communication. Both severe overconfidence and severe underconfidence may lead to the use of binary communication (e.g. "yes or no"). We also examine how confidence in communication interacts with an intrinsic "bias" of the sender. We show that slight overconfidence on the sender’s side can always (weakly) increase information transmission when he is biased, while this is not the case for underconfidence

Electroweak Sudakov corrections at 2 loop level

In processes at the energy much higher than electroweak scale, weak boson mass act as the infrared cutoff in weak boson loops and resulting Sudakov log corrections can be as large as 10%. Since electroweak theory is off-diagonally broken gauge theory, its IR structure is quite different from that of QCD. We briefly review recent developments on electroweak Sudakov and discuss on the exponentiation of Sudakov double logs and explicit 2 loop calculations in Feynman gauge.Comment: 10 pages, 2 figures, talk given at PPP2000 workshop at Chipen, Taiwan, Nov. 8-1