2016 CAP Congress / Congrès de l'ACP 2016

The spontaneous Z2 breaking Twin Higgs

16 Jun 2016, 14:30

15m

Colonel By D207 (University of Ottawa)

Oral (Student, Not in Competition) / Orale (Étudiant(e), pas dans la compétition) Particle Physics / Physique des particules (PPD) R2-3 Testing Fundamental Symmetries II (PPD-DNP-DTP) / Tests de symétries fondamentales II (PPD-DPN-DPT)

Speaker

Kevin Earl (Carleton University)

Description

The Twin Higgs model seeks to address the little hierarchy problem by making the Higgs a pseudo-Goldstone of a global $SU(4)$ symmetry that is spontaneously broken to $SU(3)$. Gauge and Yukawa couplings, which explicitly break $SU(4)$, enjoy a discrete ${\mathbb{Z}}_2$ symmetry that accidentally maintains $SU(4)$ at the quadratic level and therefore keeps the Higgs light. Contrary to most beyond the Standard Model theories, the quadratically divergent corrections to the Higgs mass are cancelled by a mirror sector, which is uncharged under the Standard Model groups. However, the Twin Higgs with an exact ${\mathbb{Z}}_2$ symmetry leads to equal vevs in the Standard Model and mirror sectors, which is phenomenologically unviable. An explicit ${\mathbb{Z}}_2$ breaking potential must then be introduced and tuned against the $SU(4)$ breaking terms to produce a hierarchy of vevs between the two sectors. This leads to a moderate but non-negligible tuning. We propose a model to alleviate this tuning, without the need for an explicit ${\mathbb{Z}}_2$ breaking sector. The model consists of two $SU(4)$ fundamental Higgses, one whose vacuum preserves ${\mathbb{Z}}_2$ and one whose vacuum breaks it. As the interactions between the two Higgses are turned on, the ${\mathbb{Z}}_2$ breaking is transmitted from the broken to the unbroken sector and a small hierarchy of vevs is naturally produced. The presence of an effective tadpole and feedback between the two Higgses lead to a sizable improvement of the tuning. The resulting Higgs boson is naturally very Standard Model like.

Presentation materials

presentation.pdf