title: Muon anomaly and dark parity violation.
abstract: The muon anomalous magnetic moment exhibits a 3.6σ discrepancy between experiment and theory. One explanation requires the existence of a light vector boson, Z(d) (the dark Z), with mass 10-500 MeV that couples weakly to the electromagnetic current through kinetic mixing. Support for such a solution also comes from astrophysics conjectures regarding the utility of a U(1)(d) gauge symmetry in the dark matter sector. In that scenario, we show that mass mixing between the Z(d) and ordinary Z boson introduces a new source of "dark" parity violation, which is potentially observable in atomic and polarized electron scattering experiments. Restrictive bounds on the mixing (m(Z(d))/m(Z))δ are found from existing atomic parity violation results, δ2<2×10(-5). Combined with future planned and proposed polarized electron scattering experiments, a sensitivity of δ2∼10(-6) is expected to be reached, thereby complementing direct searches for the Z(d) boson.
authors.affiliation: Department of Physics, Brookhaven National Laboratory, Upton, New York 11973, USA. hooman@bnl.gov
authors.forename: Hooman
authors.initials: H
authors.lastname: Davoudiasl
authors.forename: Hye-Sung
authors.initials: HS
authors.lastname: Lee
authors.forename: William J
authors.initials: WJ
authors.lastname: Marciano