title: New parity-violating muonic forces and the proton charge radius.
abstract: The recent discrepancy between proton charge radius measurements extracted from electron-proton versus muon-proton systems is suggestive of a new force that differentiates between lepton species. We identify a class of models with gauged right-handed muon number, which contains new vector and scalar force carriers at the ∼100 MeV scale or lighter, that is consistent with observations. Such forces would lead to an enhancement by several orders-of-magnitude of the parity-violating asymmetries in the scattering of low-energy muons on nuclei. The relatively large size of such asymmetries, O(10(-4)), opens up the possibility for new tests of parity violation in neutral currents with existing low-energy muon beams.
authors.affiliation: Perimeter Institute for Theoretical Physics, Waterloo, ON, Canada.
authors.forename: Brian
authors.initials: B
authors.lastname: Batell
authors.forename: David
authors.initials: D
authors.lastname: McKeen
authors.forename: Maxim
authors.initials: M
authors.lastname: Pospelov