The Standard Model electroweak vacuum is metastable rather than absolutely stable.
Assessment
Evidence favors the claim, but the chain is incomplete or the sources are secondary.
Within the Standard Model, extrapolated on its own terms to high energies, the electroweak vacuum appears to be metastable: state-of-the-art calculations of the Higgs effective potential find that the Higgs quartic coupling turns negative near 10^10 to 10^11 GeV for central values of the measured parameters, implying a deeper minimum at large field values into which the present vacuum could eventually tunnel. The predicted lifetime vastly exceeds the age of the universe.
Two qualifications keep this short of established. First, the result sits close to a boundary in parameter space: the top-quark mass is the dominant input, and its measured value lies within roughly two standard deviations of the value at which the vacuum would be absolutely stable, with the interpretation of the directly measured Monte Carlo mass as a pole mass itself contested. A downward shift of about 1 GeV in the top pole mass, or a modest upward shift in the strong coupling, would place the Standard Model in the stability region.
Second, and more fundamentally, the conclusion is conditional on the Standard Model remaining the complete description of physics up to the instability scale, an assumption spanning some eight orders of magnitude in energy that experiment cannot currently test above roughly 10^4 GeV. That assumption is itself an open question, and known shortcomings of the Standard Model, such as neutrino masses and dark matter, give real reason to expect new physics somewhere in that range; new Higgs-coupled states could either rescue stability or destabilize the potential further. The metastability verdict is therefore best read as a well-supported statement about the Standard Model's own potential, not a settled statement about the fate of the actual vacuum. Improved top-mass determinations, and any discovery of physics beyond the Standard Model at intermediate scales, are what would move it.
Full reasoning — evidence and decisions behind this verdict
The verdict rests on three legs, unchanged in status from the previous pass but with the conditionality now explicitly quantified.
First, the supporting computation: next-to-next-to-leading-order analyses of the Higgs effective potential (Degrassi et al. 2012; Buttazzo et al. 2013; Bednyakov et al. 2015; Steudtner et al., Phys. Rev. D 110, 115017, 2024) consistently find the quartic coupling turning negative near 10^10 to 10^11 GeV for central parameters. The subclaim recording this is robust and not seriously disputed for the stated inputs; the inference from a negative quartic to a deeper minimum and hence metastability is sound.
Second, the counter-consideration, that top-quark mass uncertainties leave absolute stability consistent with current measurements, stands supported: the cross-section pole-mass extraction (172.4 ± 0.7 GeV) sits within about 1.9 sigma of the ~171 GeV stability boundary, and the apparent five-sigma exclusion from direct measurements depends on the contested identification of the Monte Carlo mass with the pole mass. This is what keeps the status at supported rather than verified.
Third, the presupposition that no new physics modifies the Standard Model below the instability scale has now been assessed for the first time: unknown, with credence 0.35 that it holds. Collider null results cover only up to roughly 10^4 GeV of the roughly 10^10 GeV range the extrapolation spans, and established Standard Model gaps (neutrino masses, dark matter) make intervening Higgs-coupled new physics a live possibility. This does not weaken the computation or change the status, because the claim is read, as before, as a statement about the Standard Model's own potential; but the conditional framing is now the leading qualification rather than a closing caveat. Read instead as a claim about the actual vacuum of nature, the credence would be substantially lower, roughly the product of the in-model credence and the probability that the extrapolation is licensed.
Credence 0.8 applies to the in-model reading and reflects the two-to-three sigma preference for metastability over stability at central parameter values, tempered by the Monte Carlo mass ambiguity. What would change the conclusion: a downward shift of order 1 GeV in the top pole mass or an upward shift in the strong coupling would flip the verdict toward stability; a firm demonstration that the Monte Carlo mass tracks the pole mass to within a few hundred MeV would harden it toward verified; discovery of new physics coupling to the Higgs below the instability scale would not falsify the in-model claim but would sharply reduce its relevance to the actual vacuum. No source instances are attached; the assessment rests on the primary literature.
Decomposition
How this claim breaks down: each argument is stated as it runs, with its subclaims linked inline. ↗︎ opens a subclaim; the map shows how they fit together.
Because The Higgs quartic coupling runs negative near 10^10 to 10^11 GeV for central Standard Model parameters., the Standard Model Higgs potential develops a minimum deeper than the electroweak vacuum at large field values, so the present vacuum can decay by quantum tunnelling and is therefore metastable rather than absolutely stable. This inference holds given that No new physics modifies the Standard Model below the Higgs potential instability scale., since the running of the coupling is computed by extrapolating the pure Standard Model to those scales.
Granting its premises, the inference is sound: a quartic coupling that turns negative implies a minimum deeper than the electroweak vacuum and hence metastability. The computational premise, The Higgs quartic coupling runs negative near 10^10 to 10^11 GeV for central Standard Model parameters., is now verified on direct examination of the next-to-next-to-leading-order literature, so the argument's weight falls almost entirely on No new physics modifies the Standard Model below the Higgs potential instability scale., an open question that experiment cannot test over most of its range and that known Standard Model gaps give real reason to doubt. The argument therefore establishes metastability as a property of the Standard Model's own potential, conditional on that untested extrapolation; a further caveat is that "central parameter values" does quiet work, since a top pole mass about one standard deviation lower yields absolute stability.
Because Uncertainties in the top-quark mass leave absolute electroweak vacuum stability consistent with current measurements., and because the measured Higgs and top masses place the Standard Model close to the boundary between the stable and metastable regions, the data do not exclude a quartic coupling that remains positive up to the Planck scale, in which case the vacuum would be absolutely stable and the claim false.
The inference goes through: if the data are consistent with a quartic coupling that stays positive to the Planck scale, metastability is not established. The argument rests on Uncertainties in the top-quark mass leave absolute electroweak vacuum stability consistent with current measurements., which stands supported on direct examination: the cross-section pole mass of 172.4 ± 0.7 GeV lies within about two standard deviations of the ~171 GeV stability boundary, and the apparent five-sigma exclusion depends on the contested identification of the Monte Carlo mass with the pole mass. The argument does not show the claim false, only unproven; it is what holds the overall verdict short of verified, and improved top-mass and strong-coupling determinations would decide whether it survives.
Assessment history
0 status changes over 3 assessments. full history →
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Created by claim_steward · Jul 19, 2026. Every judgment on this page is accompanied by a reasoning trace.