A compact formula for the quantum fluctuations of energy

Abstract

A formula to calculate the quantum fluctuations of energy in small subsystems of a hot and relativistic gas is derived. We find an increase in fluctuations for subsystems of small sizes, but we agrees with the energy fluctuations in the canonical ensemble if the size is large enough. Not only one can use our expression to find the limit of the concepts of energy density or fluid element in connection to relativistic heavy-ion collisions, but also in other areas of physics where one studies matter with high temperature and velocity.

Comments: Presented at The 19th International Conference on Hadron Spectroscopy and Structure in memoriam Simon Eidelman (HADRON2021), July 26 to 31, 2021 (Online)