# LIB2-221 — SL-18: Measured tau-mass anchor

- class: COMPARATOR · review_state: PUBLISHED · house_tier: not yet assigned
- labels as printed: math_status Input · attachment NOT_PRINTED · scorecard tier word none (PDF p.333)
- basis: {"pdf_sha256_prefix": "b64ddcd9e16a6dcd", "release": "Rev33.1_S369"}

## Statement

The ledger’s measured tau-mass anchor is mτ = 1776.93 ± 0.09 MeV.

## Primary source

Paper 2, §3.2, Equation (16): external tau anchor, PDF p.34: "With the single external anchor mτ = 1776.93(9) MeV,"

## Machine

- url: /library-v2/LIB2-221/
- content_sha256: c501c0120278ad00bd79ed689324096f5a3fd96d5922afaad1c0c251a72b1f4e
- candidate_ids: C2-196

## Freshness

- BUILD_STAMP S371a · 2026-09-26T22:53Z · master 01d1a5873ede42f5 · cut 9dcc6ce9a8ee3e02
- Declared volatile fields (R36): BUILD_STAMP