31 October 2026 · three hypotheses from the 99 Original Hypotheses and Thirty Unconventional Hypotheses collections, turned into tests with the statistic and decision rule fixed before the data were touched.
All three hypotheses make the same kind of claim: that a celebrated anomaly is not in the data but in the theory, the calibration, or a single measurement. That makes them unusually cheap to attack, because the numbers needed already exist in public.
| # | Hypothesis | Test | Result |
|---|---|---|---|
| A | P18 — the determinations disagree, and one of them is biased | consistency of the three primary determinations | Partly supported. The ensemble is inconsistent at for 2 dof (); the Cs recoil value is the unique outlier, but removing it still leaves a 2.1σ residual |
| B | P02 — the muon anomaly is a hadronic-vacuum-polarisation problem | two Standard Model predictions that differ only in the HVP input, against one measurement | Supported. The anomaly is with the data-driven HVP and with the lattice HVP |
| C | P03 — the neutron-lifetime discrepancy is real and not shrinking | weighted means of the complete PDG compilation, split by technique | Supported. Beam and bottle differ by ; the tension has grown from before 2010 to after |
Two of the three survive; one survives only in a weaker form than it was stated. That is the normal yield of a test that is allowed to fail.
The two collections contain 129 entries. Most are laboratory, instrument or spacecraft proposals — deposition chambers, dilution refrigerators, synchrotrons, wet labs — and cannot be tested from a desk. The screen was:
That leaves a specific and slightly unrepresentative pool: hypotheses whose inputs are published numbers. The three below are all audits of an anomaly claim, which is why they can be done at all. The selection is a limitation of the exercise, not a judgement about the other 126 entries.
A separate forty-entry portfolio (Forty New & Original Hypotheses) was published on the Desktop while this run was in progress. It was screened too, and none of its entries cleared the bar: most call for new instrument data — a levitated nanosphere, a thorium-229 clock, a detector archive — rather than a number that already exists in public. The three below are the entries from the two established collections whose inputs could be checked today.
The pre-registered designs, including the decision rules, are in
PREREGISTRATION.md. Two earlier candidates were dropped
before any statistic was computed: E13 (Mars thermal cracking), because
the InSight catalogue’s detection is gated by the wind-noise cycle and
confounds the diurnal test it needs; and T05 (stochastic magnetic bits),
because the only available test is a model that assumes the answer.
The electron magnetic moment implies an that disagrees with atom-interferometry determinations by about ten times the new precision. The disagreement is a metrology problem in one determination, not a failure of QED.
Three determinations that do not share data:
| Determination | Method | Uncertainty | |
|---|---|---|---|
| Fan et al. 2023 | electron + QED | 137.035 999 166 | 15 × 10⁻⁹ |
| Morel et al. 2020 | ⁸⁷Rb recoil | 137.035 999 206 | 11 × 10⁻⁹ |
| Parker et al. 2018 | ¹³³Cs recoil | 137.035 999 046 | 27 × 10⁻⁹ |
CODATA 2022, 137.035 999 177(21), is a weighted combination of the recoil measurements and is not independent. It is shown as a cross-check, not counted.
The weighted mean is 137.035 999 178(8), with
The three values are not drawn from one distribution. The pulls from the mean are −0.8σ (g-2), +2.6σ (Rb) and −4.9σ (Cs). Pairwise:
| Pair | Difference (10⁻⁹) | Tension |
|---|---|---|
| Cs − Rb | 160 | 5.5σ |
| Cs − g-2 | 120 | 3.9σ |
| Rb − g-2 | 40 | 2.1σ |
The g-2 and Rb values agree at 2.1σ; the Cs value is the outlier. Removing each determination in turn:
| Dropped | (1 dof) | |
|---|---|---|
| Fan (g-2) | 30.1 | |
| Morel (Rb) | 15.1 | |
| Parker (Cs) | 4.6 | 0.032 |
The pre-registered rule asked for the leftover to exceed 0.05 after removing one determination. It reaches 0.032 — close, but not through the bar. So the verdict is split:
The hypothesis’s numerical claim about the size of the disagreement holds: the g-2/Cs difference is 8.0× the g-2 uncertainty, and the full spread is 10.7× — “about ten times the new precision”.
Verdict: partly supported. The determinations are inconsistent and the Cs recoil value is the outlier; the claim that this one measurement explains the whole discrepancy does not clear the pre-registered threshold.
The final Fermilab measurement sits between the data-driven and lattice-QCD predictions for hadronic vacuum polarisation. The true Standard Model value lies near the lattice result, so there is no anomaly to explain.
| Quantity | Value () | Source |
|---|---|---|
| , data-driven HVP (WP20) | 116 591 810(43) | arXiv:2006.04822 |
| , lattice HVP (WP25) | 116 592 033(62) | arXiv:2505.21476 |
| , final E989 | 116 592 070.5(14.6) | E989 final, June 2025 |
The two predictions differ only in the treatment of the leading-order hadronic vacuum polarisation: WP20 uses the data-driven dispersion relation, WP25 uses a consolidated lattice average. Everything else — QED, electroweak, hadronic light-by-light — is common.
Against the same measurement:
| Prediction | Tension | ||
|---|---|---|---|
| WP20 data-driven | 116 591 810(43) | 260.5 | 5.74σ |
| WP25 lattice | 116 592 033(62) | 37.5 | 0.59σ |
The two predictions differ by , or 2.96σ. The experimental uncertainty, 14.6, is four times smaller than the theory uncertainty in either scenario, so the conclusion is set entirely by which theory one believes.
Two internal checks pass. WP25 quotes the difference from its own average as ; recomputing from the numbers used here gives 37.5(63.7) — the same result to the precision quoted. And the shift between WP20 and WP25, 223(75), matches the change in the LO-HVP central value that the white paper reports as the cause.
Verdict: supported. A prediction that gives a 5.7σ anomaly and one that gives 0.6σ cannot both be right, and the experiment did not move. The anomaly lives in the HVP input.
What this does not prove is that the lattice value is the correct one. WP25 itself says the data-driven evaluations can no longer be combined because CMD-3 disagrees with the earlier experiments. The honest statement is narrower than the hypothesis: the anomaly is not robust to a defensible change in one Standard Model input, so it cannot yet be called evidence for new physics. Whether the lattice or the dispersive value is right is a separate question, and the one that will decide the fate of the anomaly.
The beam-versus-bottle discrepancy stands at 4.4σ and is a real physical effect, not mirror-neutron oscillation.
The complete PDG compilation of neutron mean-life measurements
(pdgLive node S017T, retrieved 31 October 2026). Thirty measurement rows
are parsed; the curation keeps modern entries (1995 or later), total
uncertainty at or below 5 s, and one number per apparatus lineage —
entries whose own comment says “see
| Experiment | Year | Method | (s) | σ |
|---|---|---|---|---|
| Serebrov | 2005 | bottle | 878.50 | 0.76 |
| Pichlmaier | 2010 | bottle | 880.70 | 1.77 |
| Steyerl | 2012 | bottle | 882.50 | 2.05 |
| Arzumanov | 2015 | bottle | 880.20 | 1.20 |
| Pattie | 2018 | bottle | 877.70 | 0.76 |
| Serebrov | 2018 | bottle | 881.50 | 0.92 |
| Ezhov | 2018 | bottle | 878.30 | 1.89 |
| Musedinovic | 2025 | bottle | 877.82 | 0.29 |
| Byrne | 1996 | beam | 889.20 | 4.84 |
| Yue | 2013 | beam | 887.70 | 2.25 |
| Group | Weighted mean (s) | /dof | Scale factor |
|---|---|---|---|
| Bottle (n = 8) | 878.32 ± 0.23 | 24.1/7 () | 1.85 |
| Beam (n = 2) | 887.97 ± 2.04 | 0.1/1 | — |
The tension is
or 4.63σ after applying the PDG-style scale factor to the bottle group. The hypothesis’s quoted 4.4σ is reproduced within the averaging choices.
The discrepancy is not shrinking. Splitting at 2010 (where the modern bottle programme begins):
| Epoch | Bottle | Beam | Tension |
|---|---|---|---|
| before 2010 | 878.50(76) | 889.20(4.84) | 2.18σ |
| 2010 and later | 878.30(25) | 887.70(2.25) | 4.16σ |
The bottle mean has drifted down by 0.083 ± 0.037 s per year (2.3σ), while the beam mean has not moved (−0.088 ± 0.314 s/yr). The newest and most precise bottle result, 877.82(29), is the lowest value ever published. The gap grew because the bottle measurements improved, not because they converged.
The result is stable against the one selection choice that matters. Putting the superseded Nico 2005 beam value back in — the same apparatus lineage as Yue 2013, before its fluence revision — gives a beam mean of 887.53(1.75) and a tension of 5.21σ. The pre-registered rule is met either way.
Verdict: supported. The discrepancy is real at 4.7σ, it has grown, and it is not a transient artefact of one experiment.
The second half of the hypothesis — that mirror-neutron oscillation is ruled out — is not tested here. It is an input from the PSI field-scan null, not a result of this analysis, and is reported as such.
In all three cases the experimental number is stable and the argument is about something adjacent to it:
That is the pattern the three hypotheses predicted, and it is why they were worth testing. It is also the pattern that makes them hard to finish: in each case the decisive next step is a better calculation or a better systematic control, not more data.
| Item | Source |
|---|---|
| PDG neutron mean life, node S017T | https://pdgprod.lbl.gov/pdgprod/pdgLiveJson/DataBlock.action?node=S017T,
saved as data/pdg_neutron_lifetime.html |
| from electron | Fan et al. 2023, arXiv:2209.13084 (abstract) |
| from ⁸⁷Rb recoil | Morel et al. 2020, Nature 588, 61; HAL record hal-03107990 |
| from ¹³³Cs recoil | Parker et al. 2018, Science 360, 191; Europe PMC 29650669 |
| CODATA 2022 | NIST CODATA value page,
pml.nist.gov/cgi-bin/cuu/Value?alphinv |
| data-driven | arXiv:2006.04822 (abstract) |
| lattice | arXiv:2505.21476 (abstract) |
| final E989 | E989 final result, June 2025, as stated in the source hypothesis; corroborated by the WP25 difference |
Reproduction:
python code/01_alpha_consistency.pypython code/02_muon_g2.pypython code/03_neutron_lifetime.pypython code/make_figures.pyEach writes JSON into results/; figures go to
figures/. The selected neutron-lifetime rows are written to
data/neutron_lifetime_selected.csv so the curation can be
audited.