An extension of the standard model in which parity is conserved at high energies

TL;DR

This paper proposes an extended standard model that preserves parity at high energies, introduces mirror fermions, and offers solutions to issues like the strong-CP problem and dark matter candidates.

Contribution

It presents a novel parity-invariant extension of the standard model with spontaneous parity breaking and stable mirror fermions as dark matter.

Findings

Mirror fermions acquire mass without flavor-changing neutral currents.

The model eliminates the strong-CP problem and anomalies.

Heavy mirror fermions could form dark matter candidates.

Abstract

To be compatible with general relativity, every fundamental theory should be invariant under general coordinate transformations including spatial reflection. This paper describes an extension of the standard model in which the action is invariant under spatial reflection, and the vacuum spontaneously breaks parity by giving a mean value to a pseudoscalar field. This field and the scalar Higgs field make the gauge bosons, the known fermions, and a set of mirror fermions suitably massive while avoiding flavor-changing neutral currents. In the model, there is no strong-CP problem, there are no anomalies, fermion number (quark-plus-lepton number) is conserved, and heavy mirror fermions form heavy neutral mirror atoms which are dark-matter candidates. In models with extended gauge groups, nucleons slowly decay into pions, leptons, and neutrinos.