  Prethermalization refers to the relaxation to a quasi-stationary state before
reaching thermal equilibrium. Recently, it is found that not only local
conserved quantities but also entanglement plays a key role in a special type
of prethermalization, called entanglement prethermalization. Here, we show that
in the Tomonaga-Luttinger model the entanglement prethermalization can also be
explained by the conventional prethermalization of two independent subsystems
without entanglement. Moreover, it is argued that prethermalization in the
Tomonaga-Luttinger model is essentially different from entanglement
prethermalization in the Lieb-Liniger model because of the different types of
energy degeneracies.
