Renormalization-group methods provide a viable approach for investigating the emergent collective behavior of classical and quantum statistical systems in both equilibrium and nonequilibrium conditions. Within this approach we investigate here the dynamics of an isolated quantum system represented by a scalar ${\varphi }^4$ theory after a global quench of the potential close to a dynamical critical point. We demonstrate that, within a prethermal regime, the time dependence of the relevant correlations is characterized by a short-time universal exponent, which we calculate at the lowest order in a dimensional expansion.

• Received 28 November 2014
• Revised 28 May 2015

DOI:https://doi.org/10.1103/PhysRevB.91.220302