← Back to Basic Science

Three Neutrino Families

1989
PhysicsQuantum Field Theory & Particle PhysicsEmpirical Resultfoundational

Precision measurement of the invisible decay width of the Z boson at LEP established that there are exactly 3 light neutrino species (N_v = 2.98 +/- 0.06), ruling out a hypothetical fourth generation of light neutrinos/leptons. Multiple LEP collaborations (ALEPH, DELPHI, L3, OPAL) published closely related results starting in 1989; this node anchors to the earliest of that series.

Discovery Velocity

Normalized OpenAlex paper velocity, one point per year.

Originators

  • LEP Collaborations (ALEPH, DELPHI, L3, OPAL)

Landmark Paper

W2170321376 ↗
Not retracted (OpenAlex)

Checked 2026-08-30 — interim signal only, see docs/BASIC_ROADMAP.md Phase 10

Connections

No verified edges into the applied tree or elsewhere in Basic yet — never rendered as fabricated, just absent.