Enhanced Global Symmetries and a Strong Electroweak Sector

TL;DR

This paper discusses the possibility that near a chiral phase transition, vector-like gauge theories exhibit enhanced global symmetries, which could impact electroweak symmetry breaking and related parameters.

Contribution

It proposes that near a critical fermion number, an enhanced global symmetry leads to parity doubling, influencing electroweak sector phenomenology.

Findings

Parity doubling emerges near the critical point.

Enhanced symmetry suppresses S parameter contributions.

Effective Lagrangian analysis supports the symmetry enhancement.

Abstract

In this talk I review the intriguing possibility (see Reference[1]) that the physical spectrum of a vector-like gauge field theory exhibits an enhanced global symmetry near a chiral phase transition. A transition from the Goldstone phase to the symmetric phase is expected as the number of fermions Nf is increased to some critical value. Various investigations have suggested that a parity-doubled spectrum develops as the critical value is approached. Using an effective Lagrangian as a guide one observes that a parity doubling is associated with the appearance of an enhanced global symmetry in the spectrum of the theory. If such a near-critical theory describes symmetry breaking in the electroweak theory, the additional symmetry suppresses the contribution of the parity doubled sector to the S parameter.