Question about Langevin equation The Langevin equation is given by:

$dq=pdt,\ dp=-\nabla V(q) dt-pdt+\sqrt{2}dW$
I want to know what does the variables  $p,\ q,\ t,\ V,\ W$ represent .
  Can someone help me ?
  Thanks.


you can write it in a similar way as stated in wikipedia as
$M \ddot{X} = - \nabla U(X) - \gamma \dot{X} + \sqrt{2\gamma k_{B}T}R(t)$,
where $M$ are the masses of $N$ particles and coordinates $X=X(t)$. 
$U(X)$ is the particle interaction potential, so $- \nabla U(X)$ is the force calculated from the particle interaction potentials.
$\gamma$ is a small damping constant, $\dot{X}$ is the velocity, $\ddot{X}$ is the acceleration, $T$ is the temperature, $k_{B}$ is Boltzmann's constant.
$R(t)$ is a delta-correlated stationary Gaussian process with zero-mean satisfying
$\left\langle R(t)\right\rangle =0$
$\left\langle R(t)R(t')\right\rangle =\delta(t-t')$, with $\delta$ the dirac
delta
