neutrino

Neutrino hypothesis support

Require positive compatibility evidence and explicit alternatives before accepting the classification.

1. Which production or interaction observations support a neutrino interpretation? definition
2. Which photon, neutron, unseen charged-particle or instrumental explanations remain viable? boundary

Contextual species assignment

Record each species label with its production or detection context and unresolved alternatives.

1. Does the flavour label describe production, detection or a predicted intermediate state? definition
2. Which parent process or final-state charge measurement supports the neutrino or antineutrino label? provenance
3. Must the assignment remain probabilistic because the available channel cannot distinguish the alternatives? boundary

Parent process constraints

Identify which source evidence constrains the initial flavour, energy and emission time.

1. Which decay, nuclear reaction or collision is proposed to have produced the neutrino? provenance
2. Is the association supported by a tagged parent, beam timing, directional coincidence or a population model? measurement
3. Which alternative sources remain compatible with the timing and direction uncertainties? boundary

Incoming state estimate

Record energy, direction and timing estimates together with the assumptions that produce them.

1. How is incoming neutrino energy inferred from visible products, missing energy and target recoil? measurement
2. What joint uncertainties and reaction assumptions accompany the reconstructed energy and direction? measurement
3. Does the evidence support an individual candidate estimate or only an ensemble distribution? boundary

Propagation state contract

Make basis, coherence assumptions and mixing inputs explicit before calculating a transition probability.

1. Is the initial state represented by flavour amplitudes, mass amplitudes or an incoherent mixture? definition
2. Which dated mixing-parameter fit, mass-ordering assumption and parameter correlations are used? provenance
3. Do production localization, energy resolution and baseline justify coherent evolution or averaging? boundary

Transition probability validity

Bound the calculation by path uncertainty, medium assumptions and the selected evolution approximation.

1. What baseline distribution and electron-density profile describe the proposed path? measurement
2. Are vacuum evolution, ordinary matter effects and coherent propagation sufficient for this regime? boundary
3. Which arrival-flavour probabilities can be calculated, and how must input uncertainties be propagated? action

Channel and target compatibility

Select reaction hypotheses and interaction estimates with an explicit domain of validity.

1. Which charged-current or neutral-current reactions are accessible for this energy, species and target? boundary
2. Which cross-section calculation or measurement applies, including target composition and uncertainty? provenance
3. What interaction probability follows from the target column density and applicable cross section? measurement

Candidate identification strength

Link observed products to identification confidence while preserving detector and background limitations.

1. Which tracks, showers, recoil signals or delayed coincidences support the proposed reaction? measurement
2. What flavour and neutrino-versus-antineutrino discrimination does this signature support? boundary
3. Should the agent accept, retain as ambiguous or reject the candidate after background and efficiency assessment? action

Mass constraint applicability

Require an identified observable before a mass result is used in a decision.

1. Does the result constrain an individual mass, a squared-mass difference, an effective decay mass or a cosmological mass sum? definition
2. Which confidence convention, dataset and theoretical assumptions accompany the result? provenance
3. Which conclusions about this neutrino state are justified by that observable? boundary

Hypothesis-dependent actions

Separate calculations under an extension from accepted identity claims.

1. Does the interpretation require sterile mixing, neutrino decay, a magnetic moment or lepton-number violation? definition
2. Which evidence constrains the proposed extension, and which competing explanations remain? provenance
3. Which predictions may be explored conditionally, and which identification claims must remain withheld? action

Kinds and varieties

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Electron neutrino (νe)
• Muon neutrino (νμ)
• Tau neutrino (ντ)
• Corresponding antineutrinos (ν̄e, ν̄μ, ν̄τ), distinguished in Dirac theory and in charged-current detection
• Mass eigenstates ν1, ν2, ν3 (the states that propagate)
• Sterile neutrinos (hypothetical flavours with no Standard Model weak coupling)
• Solar, atmospheric, reactor, accelerator, geoneutrino, supernova, and relic/cosmological populations (source classes used in practice)
• Dirac versus Majorana neutrinos (whether neutrino and antineutrino are distinct particles)

1. Which of these kinds and varieties hold for the sense of neutrino this model covers, and on what evidence? provenance

Identifiers and schemes

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Wikidata - Q402 - Item for the neutrino as a particle species; flavour-specific items exist separately.
• PDG Monte Carlo particle numbering - 12 (νe), 14 (νμ), 16 (ντ); negatives for antineutrinos - Standard HEP event-generator and detector-simulation codes; charged leptons are the odd numbers 11, 13, 15.

1. Which of these identifiers and schemes hold for the sense of neutrino this model covers, and on what evidence? provenance

Standards and regulation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Particle Data Group Review of Particle Physics (PDG / Lawrence Berkeley National Laboratory and collaborating labs) - de facto properties, names, and Monte Carlo numbering.
• ISO 80000-10 (ISO) - quantities and units in atomic and nuclear physics, including the notation used for neutrino-related quantities.
• IAEA technical work on reactor antineutrino monitoring - safeguards and non-proliferation applications, not a product safety code for the particle itself.

1. Which of these standards and regulation hold for the sense of neutrino this model covers, and on what evidence? provenance

Real-world use

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Detected as solar, atmospheric, reactor, and accelerator beams in underground and under-ice experiments (Super-Kamiokande, SNO, IceCube, Daya Bay, T2K, NOvA, JUNO, DUNE).
• Reactor electron antineutrinos used or proposed for remote monitoring of reactor power and fissile inventory.
• Geoneutrinos used to constrain radiogenic heat production in the Earth's crust and mantle.
• Astrophysical neutrinos (MeV supernova bursts; TeV-PeV IceCube events) used as messengers that escape dense sources.
• Cosmological relic neutrinos inferred from big-bang nucleosynthesis and CMB/large-scale structure (N_eff and Σmν), not detected as individual particles.
• Background to rare-event searches (dark matter, 0νββ) rather than a tool in those detectors.

1. Which of these real-world use hold for the sense of neutrino this model covers, and on what evidence? provenance

Typical measurements

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Rest-mass scale (direct kinematic bound on the effective electron-neutrino mass) - unknown; laboratory upper bound of order 0.45 eV (KATRIN-class tritium beta endpoint) - eV/c²
• Sum of neutrino masses (cosmological) - ≳ 0.06 (oscillation minimum) to ≲ 0.12 in typical ΛCDM analyses; model-dependent - eV/c²
• Solar-mass-squared splitting Δm²₂₁ - about 7.4×10⁻⁵ to 7.5×10⁻⁵ - eV²
• Atmospheric-mass-squared splitting |Δm²₃₁| - about 2.4×10⁻³ to 2.6×10⁻³ - eV²
• Energy of detected neutrinos - 0.1-20 MeV (solar, reactor, geo); 0.1-20 GeV (atmospheric, long-baseline beams); TeV-PeV (astrophysical) - eV (quoted in MeV, GeV, or PeV)
• Solar neutrino flux at Earth (all pp-chain flavours after oscillation) - about 6×10¹⁰ - cm⁻² s⁻¹
• Neutrino-nucleon charged-current cross section (order of magnitude) - about 10⁻³⁸ at E ~ 1 GeV, rising roughly linearly with energy in the deep-inelastic regime - cm²

1. Which of these typical measurements hold for the sense of neutrino this model covers, and on what evidence? provenance

Failure modes and hazards

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• The particle itself is not a practical radiological hazard: interaction probability in tissue is negligible at terrestrial fluxes.
• Flavour oscillation makes a produced flavour disappear and another appear; a beam or reactor monitor that assumes a fixed flavour will mis-count unless oscillation is modelled.
• Misidentification of muons, neutrons, or radioactive backgrounds as neutrino events is the dominant experimental failure mode.
• A nearby core-collapse supernova produces an intense MeV burst that is still not a human health hazard at Earth, but it can saturate neutrino detectors.
• Extra light sterile species would alter N_eff and big-bang nucleosynthesis; that is a cosmological consistency constraint, not an operational hazard.
• Detector plant hazards (cryogens, high voltage, liquid scintillator, underground fire and oxygen deficiency) are those of the apparatus, not of the neutrino.

1. Which of these failure modes and hazards hold for the sense of neutrino this model covers, and on what evidence? provenance

Regional variation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• The English name is international (neutrino / ニュートリノ / нейтрино); historical usage sometimes treated "neutrino" as the electron flavour only, with muon and tau named later.
• "Mass hierarchy" is common in East Asian and older US usage; "mass ordering" (normal vs inverted) is now preferred in many global fits.
• Practice clusters by laboratory geology more than by legal jurisdiction: Kamioka (Japan), SNOLAB (Canada), Gran Sasso (Italy), SURF (USA), JUNO (China), IceCube (South Pole).

1. Which of these regional variation hold for the sense of neutrino this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Neutron - A neutron is a baryon with mass ~939 MeV that participates in the strong interaction and beta-decays; a neutrino is a lepton with mass ≪ 1 eV that does not bind in nuclei. Track ionization and hadronic showers separate them in detectors.
• Photon - A photon couples electromagnetically (pair production, Compton, photoelectric); a neutrino does not. Neutral-current neutrino events lack the electromagnetic conversion signature of a photon of the same energy.
• Neutralino (or other WIMP) - A hypothetical supersymmetric dark-matter fermion, not a Standard Model lepton flavour. Neutrinos are produced in weak decays and oscillate among flavours; WIMP searches look for nuclear recoils without an accompanying charged lepton of definite flavour.
• Antineutrino of the same flavour - In Dirac theory they carry opposite lepton number; reactor inverse beta decay (ν̄e + p → n + e⁺) tags electron antineutrinos and does not fire on νe. If neutrinos are Majorana, the distinction is not fundamental.
• Sterile neutrino - An extra state with no Standard Model weak current. Active neutrinos produce charged-current leptons (e, μ, τ) at the appropriate energy; a sterile state does not, except through mixing.
• Cosmic-ray muon - The usual background in surface and shallow detectors. A muon leaves a long ionizing track; a neutrino is inferred from a vertex with no incoming track, often deep underground or with directional Cherenkov/timing cuts.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of neutrino this model covers, and on what evidence? provenance