The Probable Fate of the Standard Model

TL;DR

This paper assesses the long-term viability of the Standard Model by analyzing how the Higgs boson mass influences its stability or potential breakdown at high energy scales, using global fit data.

Contribution

It provides a probabilistic evaluation of the Standard Model's fate based on current Higgs mass measurements and theoretical extrapolations.

Findings

Blow-up scenario is highly disfavoured at 99% confidence level.

Standard Model may remain valid up to the Planck scale.

Metastability of the vacuum remains a plausible possibility.

Abstract

Extrapolating the Standard Model to high scales using the renormalisation group, three possibilities arise, depending on the mass of the Higgs boson: if the Higgs mass is large enough the Higgs self-coupling may blow up, entailing some new non-perturbative dynamics; if the Higgs mass is small the effective potential of the Standard Model may reveal an instability; or the Standard Model may survive all the way to the Planck scale for an intermediate range of Higgs masses. This latter case does not necessarily require stability at all times, but includes the possibility of a metastable vacuum which has not yet decayed. We evaluate the relative likelihoods of these possibilities, on the basis of a global fit to the Standard Model made using the Gfitter package. This uses the information about the Higgs mass available directly from Higgs searches at LEP and now the Tevatron, and indirectly from precision electroweak data. We find that the `blow-up' scenario is disfavoured at the 99% confidence level (96% without the Tevatron exclusion), whereas the `survival' and possible `metastable' scenarios remain plausible. A future measurement of the mass of the Higgs boson could reveal the fate of the Standard Model.