We study cold collisions between trapped ions and trapped atoms in the semiclassical (Langevin) regime. Using Yb+ ions confined in a Paul trap and Yb atoms in a magneto-optical trap, we investigate charge-exchange collisions of several isotopes over three decades of collision energies down to 3 mueV (k_{B}x35 mK). The minimum measured rate coefficient of 6x10;{-10} cm;{3} s;{-1} is in good agre...

In order to investigate dynamical symmetry breaking, we study Nambu·JonaLasinio model in the large-N limit in the stochastic quantization method. Here in order to solve Langevin equation, we impose specified initial conditions and construct “effective Langevin equation” in the large-N limit and give the same non-perturbative results as path-integral approach gives. Moreover we discuss stability...

The phase diffusion in a self-sustained oscillator, which produces oscillator’s spectral linewidth, is inherently governed by a nonlinear Langevin equation. Over past 40 years, the equation has been treated with linear approximation, rendering the nonlinearity’s effects unknown. Here we solve the nonlinear Langevin equation using the perturbation method borrowed from quantummechanics, and revea...

We present a technique to resolve the rare event problem for a Langevin equation describing a system with thermally activated transitions. A transition event within a given time interval (0,t(f)) can be described by a transition path that has an activation part during (0,t(M)) and a deactivation part during (t(M),t(f))(0<t(M)<t(f)). The activation path is governed by a Langevin equation with ne...

Influence of mesoscopic channel noise on excitable dynamics of living cells became a hot subject within the last decade, and the traditional biophysical models of neuronal dynamics such as Hodgkin-Huxley model have been generalized to incorporate such effects. There still exists but a controversy on how to do it in a proper and computationally efficient way. Here we introduce an improved Langev...

We consider numerical methods for thermodynamic sampling, i.e., computing sequences of points distributed according to the Gibbs–Boltzmann distribution, using Langevin dynamics and overdamped Langevin dynamics (Brownian dynamics). A wide variety of numerical methods for Langevin dynamics may be constructed based on splitting the stochastic differential equations into various component parts, ea...

We develop a new Lagrangian primitive, named Langevin particle, to incorporate turbulent flow details in fluid simulation. A group of the particles are distributed inside the simulation domain based on a turbulence energy model with turbulence viscosity. A particle in particular moves obeying the generalized Langevin equation, a well known stochastic differential equation that describes the par...