Gaussian Model A quench

After a sudden change from quadratic kernel $K_I(q)$ to $K_F(q)$, each Fourier mode is an Ornstein-Uhlenbeck process with decay rate $r(q)=\Gamma K_F(q)$. Its equal-time covariance interpolates exponentially between $k_{B}T/K_I(q)$ and $k_{B}T/K_F(q)$.