Parity from gauge symmetry

TL;DR

This paper proposes that Left-Right parity symmetry can originate from a unified gauge symmetry involving gravity, leading to a gravi-GUT framework where parity is spontaneously broken at lower energies.

Contribution

It introduces a novel unification scheme where parity arises as a discrete remnant of a gauge symmetry that includes gravity, extending traditional GUT models.

Findings

Parity can emerge from a unified gauge symmetry including gravity.

Possible unifying groups are SO(1,7) and SO(7,7).

Parity remains unbroken below the Planck scale and can be spontaneously broken at lower energies.

Abstract

We argue that Left-Right parity symmetry $\mathcal{P}$ can arise as a discrete remnant of a unified gauge symmetry. The high-energy unification necessarily includes the gauging of the Lorentz symmetry, bringing into the game gravitational interactions, and leading to a gravi-GUT scheme. Parity emerges unbroken below the Planck scale, and can be broken spontaneously at lower energies making contact with the Standard Model. This framework motivates the spontaneous origin of parity violation as in Left-Right symmetric theories with $\mathcal{P}$. The possible unifying gauge groups are identified as SO(1,7) for gravitational and weak interactions, or SO(7,7) for a complete unification.