Non-conformal brane plane waves and entanglement entropy

Following Narayan (2012) [4] and Narayan et al. (2013) [8], we study non-conformal brane plane wave backgrounds dual to strongly coupled gauge theories with constant energy flux and holographic entanglement entropy for strip subsystems in them. We find that for the strip direction along the direction of the energy flux, the finite cutoff-independent part of entanglement entropy can be estimated in terms of a dimensionless combination of the energy density and the strip dimensions, alongwith an effective scale-dependent number of degrees of freedom. For the strip orthogonal to the flux direction, there are indications of phase transitions. We also briefly discuss NS5-brane backgrounds corresponding to plane wave states in little string theories.