Fluctuations in the aging regime of a polymer glass

We perform numerical simulations to investigate the fluctuations in the aging regime of a system of polymers which are interacting via the Lennard-Jones potential. We characterize how the fluctuations evolve by studying (i) probability distributions of local observables such as individual particle displacements $\Delta x$ and intermediate scattering functions $C_r$ associated with small regions and (ii) dynamic correlation functions such as the four-point density correlation $g_4({\bf r}, t, t_w)$. We find that, similar to small molecule glasses, the probability distributions of local observables approximately collapse when the global two-time correlation $C_{\mbox{global}}(t,t_w)$ is held fixed. We test for universality by comparing the probability distributions in the small molecule glass with those in the polymer glass.