Alternative to Axions

Abstract

The $U(1)$ CP-violating phase which arises below chiral symmetry breaking in a non-Abelian gauge theory is ``secretly" the magnetic dual of the flux of a $U(1)$ $4$-form gauge field. Thus the discharge of this $4$-form flux by Schwinger production of charged membranes reduces the total CP-violating phase toward zero. This can safely restore CP symmetry to within the observational limits, ${\theta }_{\cancel{\mathtt{CP}}}\text{la}10^{-10}$, while also satisfying all limits from cosmology, when the charge and the tension of the gauge field sources are in the $\text{la}keV$ range.

Comments: 12+1 pages, LaTeX; accepted as a Letter to PRD; title changed in journal; references and discussion added, typos corrected