Pseudo-gauge dependence of quantum fluctuations of energy in a hot relativistic gas of fermions

Abstract

Explicit expressions for quantum fluctuations of energy in subsystems of a hot relativistic gas of spin-$1/2$ particles are derived. The results depend on the form of the energy-momentum tensor used in the calculations, which is a feature described as pseudo-gauge dependence. However, for sufficiently large subsystems the results obtained in different pseudo-gauges converge and agree with the canonical-ensemble formula known from statistical physics. As different forms of the energy-momentum tensor of a gas are a priori equivalent, our finding suggests that the concept of quantum fluctuations of energy in very small thermodynamic systems is pseudo-gauge dependent. On the practical side, the results of our calculations determine a scale of coarse graining for which the choice of the pseudo-gauge becomes irrelevant.

6 pages, 4 figures, comments are welcome

References in corpus (5)

• Hydrodynamics of spin currents
• Spin tensor and pseudo-gauges: from nuclear collisions to gravitational physics
• Intrinsic ambiguity in second order viscosity parameters in relativistic hydrodynamics
• Quantum fluctuations of energy in subsystems of a hot relativistic gas
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