Work

Gauge invariance and color charge fluctuations

Year: 2025

Type: article

Abstract: The nature of confinement is connected with color charge. Unfortunately, the color charge densities in QCD, the Noether charge densities associated with the global color invariance, are not invariant under local color rotations. This implies that the expectation values of the net color charge in any region of any physical state in QCD—states that satisfy the color Gauss law—are automatically zero for all components of color. In this Letter, it is shown that the expectation value of the square of the net color charge in a region—a measure of the color charge fluctuations—is necessarily nonzero when evaluated in physical states and the result, while depending on the scheme and scale by which the theory is regulated, is gauge invariant. This holds despite the formal lack of gauge invariance of the operator. Moreover, there is a particular combination of the color charge fluctuations for the vacuum and for a system describable by a nontrivial density matrix that is independent that has a well-defined continuum limit.

Source: Physical Review C

DOI: 10.1103/czq9-xl61

Author: Thomas D. Cohen

Institution: University of Maryland, College Park

Language: English

Topic: Quantum Chromodynamics and Particle Interactions

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Funders: U.S. Department of Energy, Nuclear Physics

Awards: G2354460126, APPROACHING QCD WITH QUANTUM SIMULATORS AND QUANTUM COMPUTERS, G4101936891, THEORETICAL STUDIES IN HADRONIC & NUCLEAR PHYSICS