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Haye Hinrichsen

Publications and source records attributed to Haye Hinrichsen.

At least 109 records · Page 6Linked to original sources
arXiv1998

Damage Spreading in a 2D Ising Model with Swendsen-Wang Dynamics

Damage spreading for 2D Ising cluster dynamics is investigated numerically by using random numbers in a way that conforms with the notion of submitting the two evolving replicas to the same thermal noise. Two damage spreading transitions are found; damage does not spread either at low or high temperatures. We determine the critical exponents at the high-temperature transition point, which seem consistent with directed percolation.

cond-mat.stat-mech↗
arXiv1998

Multicritical behavior in coupled directed percolation processes

We study a hierarchy of directed percolation (DP) processes for particle species A, B, ..., unidirectionally coupled via the reactions A -> B, ... When the DP critical points at all levels coincide, multicritical behavior emerges, with density exponents β^{(k)} which are markedly reduced at each hierarchy level k >= 2. We compute the fluctuation corrections to β^{(2)} to O(ε= 4-d) using field-theoretic renormalization group techniques. Monte Carlo simulations are employed to determine the new exponents in dimensions d <= 3.

cond-mat.stat-mech↗
arXiv1998

Identification of domain walls in coarsening systems at finite temperature

Recently B. Derrida [Phys. Rev. E 55, 3705 (1997)] introduced a numerical technique that allows one to measure the fraction of persistent spins in a coarsening nonequilibrium system at finite temperature. In the present work we extend this method in a way that domain walls can be clearly identified. To this end we consider three replicas instead of two. As an application we measure the surface area of coarsening domains in the two-dimensional Ising model at finite temperature. We also discuss the question to what extent the results depend on the algorithmic implementation.

cond-mat.stat-mech↗
arXiv1997

Numerical Study of Local and Global Persistence in Directed Percolation

The local persistence probability P_l(t) that a site never becomes active up to time t, and the global persistence probability P_g(t) that the deviation of the global density from its mean value rho(t)-<ρ(t)> does not change its sign up to time t are studied in a one-dimensional directed percolation process by Monte Carlo simulations. At criticality, starting from random initial conditions, both P_l(t) and P_g(t) decay algebraically with exponents theta_l ~ theta_g ~ 1.50(2), which is in contrast to previously known cases where theta_g < theta_l. The exponents are found to be independent of the initial density and the microscopic details of the dynamics, suggesting that theta_l and theta_g are universal exponents. It is shown that in the special case of directed-bond percolation, P_l(t) can be related to a certain return probability of a directed percolation process with an active source (wet wall).

cond-mat.stat-mech↗
arXiv1997

Smooth Phases, Roughening Transitions and Novel Exponents in One-dimensional Growth Models

A class of solid-on-solid growth models with short range interactions and sequential updates is studied. The models exhibit both smooth and rough phases in dimension d=1. Some of the features of the roughening transition which takes place in these models are related to contact processes or directed percolation type problems. The models are analyzed using a mean field approximation, scaling arguments and numerical simulations. In the smooth phase the symmetry of the underlying dynamics is spontaneously broken. A family of order parameters which are not conserved by the dynamics is defined as well as conjugate fields which couple to these order parameters. The corresponding critical behavior is studied and novel exponents identified and measured. We also show how continuous symmetries can be broken in one dimension. A field theory appropriate for studying the roughening transition is introduced and discussed.

cond-mat.stat-mech↗
arXiv1997

A Model for Nonequilibrium Wetting Transitions in Two Dimensions

A simple two dimensional model of a phase growing on a substrate is introduced. The model is characterized by an adsorption rate q, and a desorption rate p. It exhibits a wetting transition which may be viewed as an unbinding transition of an interface from a wall. For p=1, the model may be mapped onto an exactly soluble equilibrium model exhibiting complete wetting with critical exponents gamma = 1/3 for the diverging interface width and x_0 = 1 for the zero-level occupation. For 0 < p != 1 a crossover to different exponents is observed which is related to a KPZ type nonlinearity.

cond-mat.stat-mech↗
arXiv1997

Damage Spreading in the Ising Model

We present two new results regarding damage spreading in ferromagnetic Ising models. First, we show that a damage spreading transition can occur in an Ising chain that evolves in contact with a thermal reservoir. Damage heals at low temperature and spreads for high T. The dynamic rules for the system's evolution for which such a transition is observed are as legitimate as the conventional rules (Glauber, Metropolis, heat bath). Our second result is that such transitions are not always in the directed percolation universality class.

cond-mat.stat-mech↗
arXiv1997

Stochastic Lattice Models with Several Absorbing States

We study two models with n equivalent absorbing states that generalize the Domany-Kinzel cellular automaton and the contact process. Numerical investigations show that for n=2 both models belong to the same universality class as branching annihilating walks with an even number of offspring. Unlike previously known models, these models have no explicit parity conservation law.

cond-mat.stat-mech↗
arXiv1996

An Objective Definition of Damage Spreading - Application to Directed Percolation

We present a general definition of damage spreading in a pair of models. Using this general framework, one can define damage spreading in an objective manner, that does not depend on the particular dynamic procedure that is being used. The formalism is applied to the Domany-Kinzel cellular automaton in one dimension; the active phase of this model is shown to consist of three sub-phases, characterized by different damage-spreading properties.

cond-mat.stat-mech↗
arXiv1996

Universality properties of the stationary states in the one-dimensional coagulation-diffusion model with external particle input

We investigate with the help of analytical and numerical methods the reaction A+A->A on a one-dimensional lattice opened at one end and with an input of particles at the other end. We show that if the diffusion rates to the left and to the right are equal, for large x, the particle concentration c(x) behaves like As/x (x measures the distance to the input end). If the diffusion rate in the direction pointing away from the source is larger than the one corresponding to the opposite direction the particle concentration behaves like Aa/sqrt(x). The constants As and Aa are independent of the input and the two coagulation rates. The universality of Aa comes as a surprise since in the asymmetric case the system has a massive spectrum.

cond-mat.stat-mech↗
arXiv1995

Matrix Product Ground States for Asymmetric Exclusion Processes with Parallel Dynamics

We show in the example of a one-dimensional asymmetric exclusion process that stationary states of models with parallel dynamics may be written in a matrix product form. The corresponding algebra is quadratic and involves three different matrices. Using this formalism we prove previous conjectures for the equal-time correlation functions of the model.

cond-mat↗
arXiv1995

Roughening Transition in a One-Dimensional Growth Process

A class of nonequilibrium models with short-range interactions and sequential updates is presented. The models describe one dimensional growth processes which display a roughening transition between a smooth and a rough phase. This transition is accompanied by spontaneous symmetry breaking, which is described by an order parameter whose dynamics is non-conserving. Some aspects of models in this class are related to directed percolation in 1+1 dimensions, although unlike directed percolation the models have no absorbing states. Scaling relations are derived and compared with Monte Carlo simulations.

cond-mat↗
arXiv1995

Maximal Localisation in the Presence of Minimal Uncertainties in Positions and Momenta

Small corrections to the uncertainty relations, with effects in the ultraviolet and/or infrared, have been discussed in the context of string theory and quantum gravity. Such corrections lead to small but finite minimal uncertainties in position and/or momentum measurements. It has been shown that these effects could indeed provide natural cutoffs in quantum field theory. The corresponding underlying quantum theoretical framework includes small `noncommutative geometric' corrections to the canonical commutation relations. In order to study the full implications on the concept of locality it is crucial to find the physical states of then maximal localisation. These states and their properties have been calculated for the case with minimal uncertainties in positions only. Here we extend this treatment, though still in one dimension, to the general situation with minimal uncertainties both in positions and in momenta.

hep-th↗
arXiv1995

On Matrix Product Ground States for Reaction-Diffusion Models

We discuss a new mechanism leading to a matrix product form for the stationary state of one-dimensional stochastic models. The corresponding algebra is quadratic and involves four different matrices. For the example of a coagulation-decoagulation model explicit four-dimensional representations are given and exact expressions for various physical quantities are recovered. We also find the general structure of $n$-point correlation functions at the phase transition.

cond-mat↗
arXiv1995

Solution of a One-Dimensional Reaction-Diffusion Model with Spatial Asymmetry

We study classical particles on the sites of an open chain which diffuse, coagulate and decoagulate preferentially in one direction. The master equation is expressed in terms of a spin one-half Hamiltonian $H$ and the model is shown to be completely solvable if all processes have the same asymmetry. The relaxational spectrum is obtained directly from $H$ and via the equations of motion for strings of empty sites. The structure and the solvability of these equations are investigated in the general case. Two phases are shown to exist for small and large asymmetry, respectively, which differ in their stationary properties.

cond-mat↗
arXiv1994

Four State Models and Clifford Algebras

With appropriate boundary conditions the anisotropic $XY$ chain in a magnetic field is known to be invariant under quantum group transformations. We generalize this model defining a class of integrable chains with several fermionic degrees of freedom per site. In order to maintain the quantum group symmetry a general condition on the parameters of these systems is derived. It is shown that the corresponding quantum algebra is a multi-parameter deformation of the Clifford algebra. Discussing a special physical example we observe a new type of zero modes.

cond-mat↗
arXiv1994

Finite-Size-Scaling Studies of Reaction-Diffusion Systems Part II: Open Boundary Conditions

We consider the coagulation-decoagulation model on an one-dimensional lattice of length $L$ with open boundary conditions. Based on the empty interval approach the time evolution is described by a system of $\frac{L(L+1)}{2}$ differential equations which is solved analytically. An exact expression for the concentration is derived and its finite-size scaling behaviour is investigated. The scaling function is found to be independent of initial conditions. The scaling function and the correction function for open boundary conditions are different from those for periodic boundary conditions.

cond-mat↗