Pseudogauge-Invariant Nonequilibrium Density Operator

Area of Science:

• Quantum mechanics
• Statistical mechanics
• High-energy physics

Background:

• Local thermodynamic equilibrium is crucial for describing systems far from global equilibrium.
• Pseudogauge transformations affect stress-energy and spin tensors in physical systems.
• Ambiguity in predicting observable values arises from standard local equilibrium descriptions.

Purpose of the Study:

• To derive a local thermodynamic equilibrium density operator invariant under pseudogauge transformations.
• To provide a quantum state description for systems achieving local equilibrium from pseudogauge-invariant states.
• To resolve ambiguities in the predictions of mean values of observables.

Main Methods:

• Derivation of a novel density operator.
• Application of pseudogauge invariance principles.
• Analysis of stress-energy and spin tensors.

Main Results:

• Obtained a pseudogauge-invariant local thermodynamic equilibrium density operator.
• Demonstrated the operator's suitability for describing systems in local equilibrium from pseudogauge-invariant states.
• Showcased the removal of ambiguity in observable value predictions.

Conclusions:

• The derived operator offers a more precise description of systems in local thermodynamic equilibrium.
• This formalism is particularly applicable to high-energy nuclear collisions.
• Pseudogauge invariance provides a method to resolve ambiguities in quantum state predictions.