title: CP violation from five-dimensional QED.
abstract: It is shown that QED in (1 + 4)-dimensional space-time, with the fifth dimension compactified on a circle, is, in general, a CP violating theory. Depending on the fermionic boundary conditions, CP violation may be either explicit (through the Scherk-Schwarz mechanism) or spontaneous (via the Hosotani mechanism). The fifth component of the gauge field acquires (at the one-loop level) a nonzero vacuum expectation value which, in the presence of two fermionic fields, leads to spontaneous CP violation when the boundary conditions are CP symmetric. Phenomenological consequences are illustrated by a calculation of the electric dipole moment for the fermionic zero modes.
authors.affiliation: Institute of Theoretical Physics, Warsaw University Hoza 69, PL-00-681 Warsaw, Poland. bohdan.grazadkowski@fuw.edu.pl
authors.forename: Bohdan
authors.initials: B
authors.lastname: Grzadkowski
authors.forename: José
authors.initials: J
authors.lastname: Wudka