173,580 research outputs found
Monte Carlo Study of Two-Color QCD with Finite Chemical Potential - Status report of Wilson fermion simulation
Using Wilson fermions, we study SU(2) lattice QCD with the chemical potential
at . The ratio of fermion determinants is evaluated at each
Metropolis link update step. We calculate the baryon number density, the
Polyakov loops and the pseudoscalar and vector masses on and lattices. Preliminary data show the pseudoscalar meson becomes massive
around , which indicates the chiral symmetry restoration. The
calculation is broken down when approaching to the transition region. We
analyze the behavior of the fermion determinant and eigen value distributions
of the determinant, which shows a peculiar ``Shell-and-Bean'' pattern near the
transition.Comment: 4 pages, 5 figures, Lattice 2000 (Finite Density
Some classical views on the parameters of the Grothendieck-Teichmüeller group
We present two new formulas concerning behaviors of the standard parameters of the Grothendieck-Teichmüller group GT , and discuss their relationships with classical mathematics. First, considering a non-Galois etale cover of P1 {0 1 infinity} of degree 4, we present a newtype equation satisfied by the Galois image in GT . Second, a certain equation in GL 2 (Z||Z2 ) satisfied by every element of GT is derived as an application of (profinite) free differential calculus.</p
Efficient Monte Carlo algorithm in quasi-one-dimensional Ising spin systems
We have developed an efficient Monte Carlo algorithm, which accelerates slow
Monte Carlo dynamics in quasi-one-dimensional Ising spin systems. The loop
algorithm of the quantum Monte Carlo method is applied to the classical spin
models with highly anisotropic exchange interactions. Both correlation time and
real CPU time are reduced drastically. The algorithm is demonstrated in the
layered triangular-lattice antiferromagnetic Ising model. We have obtained the
relation between the transition temperature and the exchange interaction
parameters, which modifies the result of the chain-mean-field theory.Comment: 4 pages, 3 figure
Identification of topologically different valence bond states in spin ladders
We discuss relation between three different methods to identify topologically
distinct short-range valence-bond ground states in spin- two-leg
ladders: the string order parameters, the level-crossing method, and the
ground-state expectation value of the twist operator. For this purpose we
reexamine a phase transition in the frustrated spin ladder. We propose a proper
bosonization of the string order parameters. Then, these three methods are
shown to be equivalent reflecting the symmetry breaking of the
order and the disorder fields of the two-dimensional Ising model.Comment: 2 pages, Proceedings for LT2
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