BibTeX
@MISC{Lavoura08softcp,
author = {L. Lavoura},
title = {Soft CP breaking and the strong-CP problem},
year = {2008}
}
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Abstract
I put forward a model with vectorlike isosinglet quarks in which soft breaking of CP leads to strong CP violation only arising at two-loop level. Non-perturbative effects in Quantum Chromodynamics (QCD) may lead to P and CP violation, characterized by a parameter θ, in strong interactions. The experimental upper bound on the electric dipole moment of the neutron requires θ< ∼ 2 × 10 −10 [1]. (Electric dipole moments of elementary particles are both P-and T-violating; in normal field theory, T violation is equivalent to CP violation.) The presence of this unnaturally small number in QCD is known as the strong-CP problem. θ is the sum of two terms, θQCD and θQFD. θQCD is the original value of the angle θ characterizing the QCD vacuum. θQFD originates in the chiral rotation of the quark fields needed to render the quark masses real and positive. If Mp and Mn are the mass matrices of the up-type (charge 2/3) and down-type (charge
Keyphrases
strong-cp problem soft cp breaking electric dipole moment cp violation quark field strong interaction quantum chromodynamics soft breaking strong cp violation elementary particle non-perturbative effect p-and t-violating experimental upper bound qcd vacuum chiral rotation original value vectorlike isosinglet quark two-loop level small number mass matrix normal field theory
