PreliminaryBari Release 2026.a: preliminary results, the paper is in preparation. Values may still change; no data files are distributed yet.

Current results

Bari Release 2026.a Preliminary

full releasevalues as of 2026-10-15; paper in preparation

Preliminary Bari Release 2026.a: the paper is in preparation and these values may still change. Data files will be published with the paper.

Best fit, normal ordering (NO); the inverted-ordering (IO) value below each.

δm² / 10⁻⁵ eV²
7.465±0.076
IO 7.439
sin²θ₁₂
0.3047±0.0055
IO 0.3036
Δm² / 10⁻³ eV²
2.4720±0.0134
IO −2.4810
sin²θ₁₃
0.02218±0.00055
IO 0.0223
sin²θ₂₃
0.491+0.047−0.021
IO 0.5446
δ/π
1.19±0.15
IO 1.52

NO IO · Nσ = √Δχ² up to 5σ, both orderings on the common scale (guides at 1σ and 3σ); shaded: the 1σ range (NO). Profiles of the final combination.

Normal ordering favoured at 3.9σ · Δχ²(IO−NO) = +15.34

What changed

against the published values (2025 release with the 2026 (1, 2)-sector update)

  • δm² 1σ accuracy 1.3% → 1.0%*
  • sin²θ₁₂ 1σ accuracy 2.4% → 1.8%*
  • Δm² 1σ accuracy 0.8% → 0.5%*
  • sin²θ₁₃ 1σ accuracy 2.4% → 2.5%*
  • sin²θ₂₃ 1σ accuracy 5.1% → 4.4%*
  • δ/π 1σ accuracy 18% → 12.3%*
  • Ordering NO at 2.2σ → NO at 3.9σ (Δχ² +5.0 → +15.34)

1σ accuracy, in percent. Bari Release 2026.a: the 1σ error (half the 1σ range) divided by the best fit — its errors are Gaussian to a very good approximation; δ/π too, whose profile is far from Gaussian but not because of the octant degeneracy — except sin²θ₂₃: one sixth of the 3σ range divided by the best fit, since its range spans both octants. Earlier releases: as published, one sixth of the 3σ range divided by the best fit, in percent, as in the tables of our papers.

* computed from the release's unrounded ranges, with its definition stated above.

The six parameters, as measured

current values · normal ordering

-20% -10% best fit +10% +20% δm² / 10⁻⁵ eV² 3σ: 7.239 – 7.681 (−3% / +3%) 1σ: 7.386 – 7.538 (−1% / +1%) best fit 7.465 7.465 sin²θ₁₂ / 10⁻¹ 3σ: 2.888 – 3.217 (−5% / +6%) 1σ: 2.993 – 3.104 (−2% / +2%) best fit 3.047 3.047 Δm² / 10⁻³ eV² 3σ: 2.4317 – 2.5174 (−2% / +2%) 1σ: 2.4586 – 2.4853 (−1% / +1%) best fit 2.4720 2.4720 sin²θ₁₃ / 10⁻² 3σ: 2.05 – 2.38 (−8% / +7%) 1σ: 2.16 – 2.27 (−3% / +2%) best fit 2.22 2.22 sin²θ₂₃ / 10⁻¹ 3σ: 4.439 – 5.735 (−10% / +17%) 1σ: 4.703 – 5.383 (−4% / +10%) best fit 4.908 4.908 δ/π 3σ: 0.79 – 1.95 (−33% / +65%) 1σ: 1.05 – 1.34 (−11% / +13%) best fit 1.19 1.19 −34% +64% width = 3σ range as a percentage of the best fit Bari Release 2026.a

Best fit with 1σ and 3σ ranges for the current values in the panel above, normal ordering. All six rows share one scale, in percent of each parameter's own best fit, so the width of a row is how well that parameter is known; a row that runs past the axis is marked with an arrow and its true extent. Absolute values are printed at the right. Full tables and both orderings are on the results page.

How the precision improved

1σ accuracy · logarithmic scale

1% 2% 5% 10% 20% 2011 2012 2013 2016 2017 2018 2021 2025 2026 δm², 2011: 1σ accuracy 2.6% δm², 2012: 1σ accuracy 2.6% δm², 2013: 1σ accuracy 2.6% δm², 2016: 1σ accuracy 2.4% δm², 2017: 1σ accuracy 2.3% δm², 2018: 1σ accuracy 2.2% δm², 2021: 1σ accuracy 2.3% δm², 2025: 1σ accuracy 2.3% δm², 2026: 1σ accuracy 1.3% δm², 2026.a: 1σ accuracy 1.0% Δm², 2011: 1σ accuracy 4.3% Δm², 2012: 1σ accuracy 2.9% Δm², 2013: 1σ accuracy 2.6% Δm², 2016: 1σ accuracy 1.7% Δm², 2017: 1σ accuracy 1.6% Δm², 2018: 1σ accuracy 1.4% Δm², 2021: 1σ accuracy 1.1% Δm², 2025: 1σ accuracy 0.8% Δm², 2026.a: 1σ accuracy 0.5% sin²θ₁₂, 2011: 1σ accuracy 5.4% sin²θ₁₂, 2012: 1σ accuracy 5.4% sin²θ₁₂, 2013: 1σ accuracy 5.4% sin²θ₁₂, 2016: 1σ accuracy 5.8% sin²θ₁₂, 2017: 1σ accuracy 5.8% sin²θ₁₂, 2018: 1σ accuracy 4.4% sin²θ₁₂, 2021: 1σ accuracy 4.5% sin²θ₁₂, 2025: 1σ accuracy 4.5% sin²θ₁₂, 2026: 1σ accuracy 2.4% sin²θ₁₂, 2026.a: 1σ accuracy 1.8% sin²θ₁₃, 2011: 1σ accuracy 34.1% sin²θ₁₃, 2012: 1σ accuracy 10.0% sin²θ₁₃, 2013: 1σ accuracy 8.5% sin²θ₁₃, 2016: 1σ accuracy 4.8% sin²θ₁₃, 2017: 1σ accuracy 3.9% sin²θ₁₃, 2018: 1σ accuracy 3.8% sin²θ₁₃, 2021: 1σ accuracy 3.0% sin²θ₁₃, 2025: 1σ accuracy 2.4% sin²θ₁₃, 2026.a: 1σ accuracy 2.5% sin²θ₂₃, 2011: 1σ accuracy 11.9% sin²θ₂₃, 2012: 1σ accuracy 13.2% sin²θ₂₃, 2013: 1σ accuracy 9.6% sin²θ₂₃, 2016: 1σ accuracy 9.0% sin²θ₂₃, 2017: 1σ accuracy 9.2% sin²θ₂₃, 2018: 1σ accuracy 5.2% sin²θ₂₃, 2021: 1σ accuracy 6.7% sin²θ₂₃, 2025: 1σ accuracy 5.1% sin²θ₂₃, 2026.a: 1σ accuracy 4.4% δ/π, 2018: 1σ accuracy 14.6% δ/π, 2021: 1σ accuracy 16.1% δ/π, 2025: 1σ accuracy 18% δ/π, 2026.a: 1σ accuracy 12.3% δ/π sin²θ₂₃ sin²θ₁₃ sin²θ₁₂ δm² Δm² last point: release 2026.a (preliminary, values of 2026-10-15)

Each line is one parameter’s 1σ accuracy in each release — a sixth of its 3σ range over its best fit, as in the tables of our papers; for Bari Release 2026.a its 1σ error over its best fit (sin²θ₂₃: a sixth of the 3σ range), see the note under the results. Computed from the same tables the parameter history is built on.