A sluggish random walk with subdiffusive spread

Abstract

We study a one-dimensional sluggish random walk with space-dependent transition probabilities between nearest-neighbour lattice sites. Motivated by trap models of slow dynamics, we consider a model in which the trap depth increases logarithmically with distance from the origin. This leads to a random walk which has symmetric transition probabilities that decrease with distance $|k|$ from the origin as $1/|k|$ for large $|k|$. We show that the typical position after time $t$ scales as $t^{1/3}$ with a nontrivial scaling function for the position distribution which has a trough (a cusp singularity) at the origin. Therefore an effective central bias away from the origin emerges even though the transition probabilities are symmetric. We also compute the survival probability of the walker in the presence of a sink at the origin and show that it decays as $t^{-1/3}$ at late times. Furthermore we compute the distribution of the maximum position, $M(t)$, to the right of the origin up to time $t$, and show that it has a nontrivial scaling function. Finally we provide a generalisation of this model where the transition probabilities decay as $1/|k{|}^{\alpha }$ with $\alpha >0$.

arXiv comment17 pages, revised version accepted for J. Stat. Mech

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• Universal singularities of anomalous diffusion in the Richardson class
• First-passage functionals of Brownian motion in logarithmic potentials and heterogeneous diffusion
• Generalized arcsine laws for a sluggish random walker with subdiffusive growth
• Random search with resetting in heterogeneous environments
• Random-search efficiency in a bounded interval with spatially heterogeneous diffusion coefficient
• The stochastic porous medium equation in one dimension
• Proxitaxis: an adaptive search strategy based on proximity and stochastic resetting
• Ultra slow sub-logarithmic diffusion of a sluggish random walker subject to resetting with memory
• Extreme value statistics in a continuous time branching process: a pedagogical primer