Noninertial equations, Langevin equation

We form the average of Eqs. (5.20)-(5.22) noting that (L(r)) will vanish throughout because, in the inertia corrected Langevin equation, M is statistically independent of the white noise field h(r). This is not, however, true of the noninertial Langevin equation where the multiplicative noise term L(f) contributes a noise induced drift term to the average (see Section VI). The averages so formed are... 

This is the Langevin equation for the motion of p, in the noninertial limit. 

Now we illustrate how the differential-difference equation for (Pj) may be obtained by averaging the noninertial Langevin equation. We recall that for a longitudinal field Fq,... 

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