Does chiral perturbation theory rule out QCD-based solutions to the strong CP problem?

Cohen, Thomas D. (Department of Physics and the Maryland Center for Fundamental Physics University of Maryland, 20742 Maryland, USA)

07 May 2019

Abstract: The conventional view is that a solution of the strong CP problem lies beyond QCD. A strong argument supporting this view is that the chiral expansion shows that observables depend on theta (unless a quark mass is zero); this eliminates the possibility that theta is physically irrelevant and appears to necessitate an explanation beyond the standard model. However, scenarios that solve the strong CP problem that are consistent with known chiral behavior exist; in these, QCD becomes nonviable as a theory for nonzero theta. Such scenarios appear to be compatible with lattice studies of the topological susceptibility.

Published in: Physical Review D 99 (2019)
Published by: APS
DOI: 10.1103/PhysRevD.99.094007
arXiv: 1811.04833
License: CC-BY-4.0

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