2,533 research outputs found
Dynamic SU(2) Lattice Gauge Theory at Finite Temperature
The dynamic relaxation process for the (2+1)--dimensional SU(2) lattice gauge
theory at critical temperature is investigated with Monte Carlo methods. The
critical initial increase of the Polyakov loop is observed. The dynamic
exponents and as well as the static critical exponent
are determined from the power law behaviour of the Polyakov loop, the
auto-correlation and the second moment at the early stage of the time
evolution. The results are well consistent and universal short-time scaling
behaviour of the dynamic system is confirmed. The values of the exponents show
that the dynamic SU(2) lattice gauge theory is in the same dynamic universality
class as the dynamic Ising model.Comment: 10 pages with 2 figure
On the Segregation Phenomenon in Complex Langevin Simulation
In the numerical simulation of certain field theoretical models, the complex
Langevin simulation has been believed to fail due to the violation of
ergodicity. We give a detailed analysis of this problem based on a toy model
with one degree of freedom (). We find that the failure is
not due to the defect of complex Langevin simulation itself, but rather to the
way how one treats the singularity appearing in the drift force. An effective
algorithm is proposed by which one can simulate the behaviour of
the expectation value in the small limit.Comment: (20 pages + 8 figures on request). Siegen Si-93-8, Tokuyama TKYM-93-
Short-time critical dynamics and universality on a two-dimensional Triangular Lattice
Critical scaling and universality in short-time dynamics for spin models on a
two-dimensional triangular lattice are investigated by using Monte Carlo
simulation. Emphasis is placed on the dynamic evolution from fully ordered
initialstates to show that universal scaling exists already in the short-time
regime in form of power-law behavior of the magnetization and Binder cumulant.
The results measured for the dynamic and static critical exponents, ,
, and , confirm explicitly that the Potts models on the
triangular lattice and square lattice belong to the same universality class.
Our critical scaling analysis strongly suggests that the simulation for the
dynamic relaxation can be used to determine numerically the universality.Comment: LaTex, 11 pages and 10 figures, to be published in Physica
Universality and Scaling in Short-time Critical Dynamics
Numerically we simulate the short-time behaviour of the critical dynamics for
the two dimensional Ising model and Potts model with an initial state of very
high temperature and small magnetization. Critical initial increase of the
magnetization is observed. The new dynamic critical exponent as well
as the exponents and are determined from the power law
behaviour of the magnetization, auto-correlation and the second moment.
Furthermore the calculation has been carried out with both Heat-bath and
Metropolis algorithms. All the results are consistent and therefore
universality and scaling are confirmed.Comment: 14 pages, 14 figure
Characterization of the replication of a baculovirus mutant lacking the DNA polymerase gene
AbstractIn a previous study, the DNA polymerase gene (dnapol) of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) was identified as one of six genes required for plasmid replication in a transient replication assay (M. Kool, C. Ahrens, R.W. Goldbach, G.F. Rohrmann, J.M. Vlak, Identification of genes involved in DNA replication of the Autographa californica, Proc. Natl. Acad. Sci. U.S.A. 91, (1994) 11212–11216); however, another study based on a similar approach reported that the virally encoded polymerase was only stimulatory (A. Lu, L.K. Miller, The roles of 18 baculovirus late expression factor genes in transcription and DNA replication, J. Virol. 69, (1995) 975–982). To reconcile the conflicting data and determine if the AcMNPV DNA polymerase is required for viral DNA replication during the course of an infection, a dnapol-null virus was generated using bacmid technology. To detect viral DNA replication, a highly sensitive assay was designed based on real-time PCR and SYBR green chemistry. Our results indicate that a bacmid in which the dnapol ORF was deleted is unable to replicate its DNA when transfected into Spodoptera frugiperda (Sf-9) cells, although when the dnapol ORF was introduced into the polyhedrin (polh) locus, this repaired virus could propagate at levels similar to the control virus. These results confirm that the AcMNPV-encoded DNA polymerase is required for viral DNA replication and the host DNA polymerases cannot substitute for the viral enzyme in this process
Dynamic Monte Carlo Study of the Two-Dimensional Quantum XY Model
We present a dynamic Monte Carlo study of the Kosterlitz-Thouless phase
transition for the spin-1/2 quantum XY model in two dimensions. The short-time
dynamic scaling behaviour is found and the dynamical exponent , and
the static exponent are determined at the transition temperature.Comment: 6 pages with 3 figure
Determination of the Critical Point and Exponents from short-time Dynamics
The dynamic process for the two dimensional three state Potts model in the
critical domain is simulated by the Monte Carlo method. It is shown that the
critical point can rigorously be located from the universal short-time
behaviour. This makes it possible to investigate critical dynamics
independently of the equilibrium state. From the power law behaviour of the
magnetization the exponents and are determined.Comment: 6 pages, 4 figure
Universal Short-time Behaviour of the Dynamic Fully Frustrated XY Model
With Monte Carlo methods we investigate the dynamic relaxation of the fully
frustrated XY model in two dimensions below or at the Kosterlitz-Thouless phase
transition temperature. Special attention is drawn to the sublattice structure
of the dynamic evolution. Short-time scaling behaviour is found and
universality is confirmed. The critical exponent is measured for
different temperature and with different algorithms.Comment: 18 pages, LaTeX, 8 ps-figure
Dynamical and stationary critical behavior of the Ising ferromagnet in a thermal gradient
In this paper we present and discuss results of Monte Carlo numerical
simulations of the two-dimensional Ising ferromagnet in contact with a heat
bath that intrinsically has a thermal gradient. The extremes of the magnet are
at temperatures , where is the Onsager critical temperature.
In this way one can observe a phase transition between an ordered phase
() by means of a single simulation. By
starting the simulations with fully disordered initial configurations with
magnetization corresponding to , which are then suddenly
annealed to a preset thermal gradient, we study the short-time critical dynamic
behavior of the system. Also, by setting a small initial magnetization ,
we study the critical initial increase of the order parameter. Furthermore, by
starting the simulations from fully ordered configurations, which correspond to
the ground state at T=0 and are subsequently quenched to a preset gradient, we
study the critical relaxation dynamics of the system. Additionally, we perform
stationary measurements () that are discussed in terms of
the standard finite-size scaling theory. We conclude that our numerical
simulation results of the Ising magnet in a thermal gradient, which are
rationalized in terms of both dynamic and standard scaling arguments, are fully
consistent with well established results obtained under equilibrium conditions
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