Search arXiv⌕ Search

arXiv subjects

Theophilus Dwamena Frimpong

Publications and source records attributed to Theophilus Dwamena Frimpong.

2 recordsLinked to original sources

Extremal and global-time statistics of sluggish random walks with stochastic resetting

We study a sluggish random walk, whose diffusivity decreases as a power law with distance from the origin, under Poissonian resetting to the origin. Using a mapping to a signed Bessel process and renewal theory, we obtain exact results for the maximum trajectory value in a finite window, the time at which it occurs, and the time of the last visit to the origin. Resetting changes the growth of the typical maximum from a power law in time to a power of its logarithm. The centered maximum approaches a Gumbel law, whose width shrinks in physical space for any positive sluggishness exponent, unlike the Brownian case. In the Bessel coordinate, the probability that the maximum exceeds a value growing in proportion to the observation window length decays exponentially, with a rate that has a second-order dynamical transition and is independent of sluggishness. The time of the maximum is uniform in the bulk, with boundary layers that shift its mean above the midpoint logarithmically with window length. The time since the last visit to the origin follows a Gamma law with a sluggishness-dependent shape. Reflection symmetry makes the last-visit time uncorrelated with the occupation time of the positive half-line.

cond-mat.stat-mech↗

Sluggish random walks with resetting: nonequilibrium aspects

We derive exact analytical expressions for the fixed-time probability distribution and the Laplace transform of the distribution of the first-passage time to reach a target for a sluggish random walk in one dimension subject to two different types of stochastic resetting: stochastic resetting at random Poisson-distributed times, and resetting implemented whenever a position threshold is reached. The optimal resetting rate that minimises the mean first-passage time is obtained as a function of the sluggishness parameter, while under threshold resetting the mean first-passage time to the origin is found to increase monotonically with the threshold. We also characterise the occupation-time statistics, retrieving a Lamperti-type distribution under free dynamics and under Poissonian resetting at rate for short observation times, a Gaussian distribution centred at half for long observation times, and a distinct deterministic limit under threshold resetting. To further characterise nonequilibrium aspects of resetting, we evaluate the distribution and mean of the cost incurred per reset under Poissonian resetting, and the cost rate under threshold resetting, for different (linear, power-law, exponential) cost functions, and find the same critical behaviour of the cost rate in the limits of a vanishing resetting rate and an infinite threshold, respectively. Numerical simulations validate with excellent accuracy our analytical formulae.

cond-mat.stat-mech↗