The anomalous shift of the weak boson mass and the quintessence electroweak axion

TL;DR

This paper explores how a triplet Higgs boson can explain the W-boson mass shift and, through a larger gauge coupling, how an electroweak axion could account for the cosmological constant, linking particle physics and cosmology.

Contribution

It proposes a model combining a triplet Higgs and an electroweak axion to simultaneously address the W-boson mass anomaly and the cosmological constant problem.

Findings

Triplet Higgs explains W-boson mass shift without conflicting with observations.

Enhanced gauge coupling at Planck scale supports electroweak axion dark energy.

Electroweak axion near the hill top accounts for observed cosmological constant.

Abstract

One of the simplest ways to account for the observed W-boson mass shift is to introduce the $SU(2)_L$ triplet Higgs boson with zero hypercharge, whose vacuum expectation value is about 3 GeV. If the triplet is heavy enough at $\mathcal{O}(1)$ TeV, it essentially contributes only to $T$ parameter without any conflict to the observation. The presence of a complex triplet Higgs boson raises the $SU(2)_L$ gauge coupling constant to $\alpha_2(M_{\rm PL} )\simeq 1/44$ at the Planck scale. Thanks to this larger gauge coupling constant, we show that the electroweak axion vacuum energy explains the observed cosmological constant provided that the axion field is located near the hill top of the potential at present.