TeV Symmetry and the Little Hierarchy Problem

TL;DR

This work addresses the tension between precision electroweak constraints and naturalness by introducing a discrete TeV-scale symmetry, $T$-parity, within a $SO(5)$ little Higgs framework. The authors construct a concrete three-site moose model in which $T$-parity suppresses tree-level contributions from new TeV-scale states while preserving one-loop cancellations that stabilize the Higgs mass up to $10$ TeV. The model predicts a two-Higgs-doublet low-energy sector, $T$-odd heavy states, and a stable LTP dark matter candidate, yielding collider signatures similar to SUSY with $R$-parity and distinctive dark matter phenomenology. Overall, this approach reconciles naturalness with precision data and motivates novel LHC and astrophysical searches for TeV-scale parity-odd particles.

Abstract

Constraints from precision electroweak measurements reveal no evidence for new physics up to 5 - 7 TeV, whereas naturalness requires new particles at around 1 TeV to address the stability of the electroweak scale. We show that this "little hierarchy problem" can be cured by introducing a symmetry for new particles at the TeV scale. As an example, we construct a little Higgs model with this new symmetry, dubbed T-parity, which naturally solves the little hierarchy problem and, at the same time, stabilize the electroweak scale up to 10 TeV. The model has many important phenomenological consequences, including consistency with the precision data without any fine-tuning, a stable weakly-interacting particle as the dark matter candidate, as well as collider signals completely different from existing little Higgs models, but rather similar to the supersymmetric theories with conserved R-parity.

Figures (1)

• Figure 1: The moose diagram for the theory space. It has the topology of a torus.