Can confinement ensure natural CP invariance of strong interactions?
Abstract
P and Tinvariance violation in quantum chromodynamics due to the socalled θterm is discussed. It is shown that irrespectively of how the confinement works there emerge observable P and Todd effects. The proof is based on the assumption that QCD resolves the U(1) problem, i.e., the mass of the singlet pseudoscalar meson does not vanish in the chiral limit. We suggest a modification of the axion scheme which restores the natural P and T invariance of the theory and cannot be ruled out experimentally.
 Publication:

Nuclear Physics B
 Pub Date:
 April 1980
 DOI:
 10.1016/05503213(80)902096
 Bibcode:
 1980NuPhB.166..493S