Pseudogauge-Invariant Nonequilibrium Density Operator.

We obtain a form of the local thermodynamic equilibrium density operator, which is invariant under pseudogauge transformations of the stress-energy and the spin tensors. This operator is an excellent candidate to describe the dynamics of a system that is assumed to achieve local equilibrium from a pseudogauge-invariant quantum state, a situation that is believed to occur, for instance, in nuclear collisions at very high energy. As a consequence of pseudogauge invariance, the ambiguity affecting the predictions of mean values of observables from a local equilibrium state can be removed.