[Paper Review] 125 GeV Higgs Boson From Gauge-Higgs Unification: A Snowmass white paper

Ilia Gogoladze, Nobuchika Okada+1 more|arXiv (Cornell University)|Jul 18, 2013

Particle physics theoretical and experimental studies4 references3 citations

TL;DR

This paper proposes a five-dimensional gauge-Higgs unification model where the Higgs boson mass is predicted via unification of the top quark Yukawa and SU(2) gauge couplings at a compactification scale near 10⁹ GeV. The model reproduces the observed 125 GeV Higgs mass within experimental uncertainties of top quark and QCD coupling measurements, offering a natural mechanism for electroweak symmetry breaking and a testable prediction for new physics.

ABSTRACT

In certain five dimensional gauge theories compactified on the orbifold $S^1/Z_2$ the Standard Model Higgs doublet is identified with the zero mode of the fifth component of the gauge field. This gauge-Higgs unification scenario is realized at high energies, and the Standard Model as an effective theory below the compactification scale satisfies the boundary condition that the Higgs quartic coupling vanishes at the compactification scale (gauge-Higgs condition). This is because at energies above the compactification scale, the five dimensional gauge invariance is restored and the Higgs potential vanishes as a consequence. We consider scenario where top quark Yukawa and weak gauge coupling unification can be realized and identify the compactification scale as one at which this two coupling couplings have the same value. Taking into account the experimental uncertainties in measurements of the top quark mass and the QCD coupling constant, the Higgs mass prediction of 119-126 GeV from the gauge-Higgs unification scenario is consistent with the experimentally measured value of 125-126 GeV. More precise measurements of the top quark mass and the QCD coupling constant are crucial to reduce the interval of the Higgs mass prediction and thereby test the feasibility of the gauge-Higgs unification scenario.

Motivation & Objective

• To explore whether gauge-Higgs unification in a 5D SU(3)×U(1)' model can naturally explain the 125 GeV Higgs boson mass observed at the LHC.
• To determine the compactification scale as the unification scale of the top quark Yukawa and SU(2) gauge couplings.
• To test the consistency of the gauge-Higgs unification scenario with experimental measurements of the top quark pole mass and QCD coupling constant.
• To assess the predictive power of the model by evaluating the Higgs mass prediction range under current experimental uncertainties.
• To identify future precision measurements of the top quark mass and α₃(m_Z) as critical tests for validating the gauge-Higgs unification framework.

Proposed method

• Utilizes a 5D SU(3) gauge theory compactified on the S¹/Z₂ orbifold, where the Higgs doublet arises as the zero mode of the fifth-dimensional gauge field.
• Imposes the gauge-Higgs condition: the Higgs quartic coupling vanishes at the compactification scale due to restored 5D gauge invariance.
• Applies two-loop renormalization group equations (RGEs) of the Standard Model to run couplings from the Z-boson scale down to the compactification scale.
• Identifies the compactification scale μ as the unification point of the SU(2) gauge coupling and top quark Yukawa coupling, derived from RGE running with input values of Mₜ and α₃(m_Z).
• Uses the gauge-Higgs condition at the unification scale to evolve the Higgs quartic coupling down to the electroweak scale, computing the physical Higgs pole mass via matching conditions.
• Varying input parameters within experimental uncertainties (172.24–174.12 GeV for Mₜ, 0.1179–0.1193 for α₃(m_Z)) to map the predicted Higgs mass range.

Experimental results

Research questions

• RQ1 Can the observed 125 GeV Higgs boson mass be naturally explained within a gauge-Higgs unification framework in 5D spacetime?
• RQ2 At what compactification scale do the SU(2) gauge coupling and top quark Yukawa coupling unify in the 5D model?
• RQ3 How sensitive is the predicted Higgs mass to experimental uncertainties in the top quark pole mass and QCD coupling constant?
• RQ4 Does the gauge-Higgs unification scenario predict a Higgs mass consistent with the LHC measurement of 125 GeV within current experimental errors?
• RQ5 What precision measurements are required to test the viability of the gauge-Higgs unification model?

Key findings

• The SU(2) gauge coupling and top quark Yukawa coupling unify at a compactification scale of approximately 10⁹ GeV, identified as the energy scale of the 5D theory.
• The predicted Higgs boson mass ranges from 119 GeV to 126 GeV, depending on input values of the top quark pole mass and α₃(m_Z), which is consistent with the observed 125–126 GeV value.
• The model's prediction is most consistent with the measured Higgs mass when the top quark pole mass is at the upper end of its uncertainty range and α₃(m_Z) is at the lower end.
• The Higgs mass prediction is highly sensitive to the precision of Mₜ and α₃(m_Z), making future improvements in these measurements crucial for testing the model.
• The gauge-Higgs unification scenario provides a dynamical mechanism for electroweak symmetry breaking without introducing a fundamental Higgs field, with the Higgs potential generated via quantum corrections from Kaluza-Klein modes.
• The model realizes a natural unification of the top quark and weak gauge interactions at the compactification scale, offering a potential explanation for the hierarchy between the top quark and W boson masses.