name: pdg-lookup
description: Use when the user asks for a canonical Particle Data Group value — particle mass, lifetime, branching ratio, decay width, magnetic moment, mixing parameter, charge, spin, or any quoted "PDG average" constant. Backed by https://pdg.lbl.gov/ via WebFetch (HTML pdgLive pages and the PDG REST API where available). Always cites the PDG record URL and edition year. Does NOT cover ATLAS Monte Carlo metadata (use atlas-opendata), measured values from a specific paper (use read-publication), HEPData tabulated measurements (use hepdata), or conceptual physics explanations of why a particle has the value it does (use the tutor agent). Disambiguator phrase: PDG particle data group lookup.
data_scope: both
experiment: all
pdg-lookup — canonical particle physics constants
This skill is the only correct path for quoting a particle mass, lifetime,
branching ratio, or any other PDG-averaged constant. Critical rule 5
forbids quoting these from training-data memory.
Scope
Load this skill when the user asks for a canonical particle physics
constant — values that appear in the PDG Review and pdgLive listings.
Examples:
- "What is the Z mass?"
- "Look up the muon lifetime."
- "What's BR(B0 → K*0 μ+ μ-)?"
- "What's the τ → πν branching fraction?"
Do NOT load this skill for:
- A measurement from a specific paper or experiment →
read-publication.
- Numerical tables attached to a published measurement →
hepdata.
- ATLAS / CMS Monte Carlo cross-section metadata →
atlas-opendata
(DSID, generator-level cross-section, k-factor — not the same as
PDG-averaged values).
- Conceptual explanations ("why does the Z have a mass") →
tutor agent.
The always-cite rule
Every value quoted from this skill MUST include:
- The numerical value with units.
- The PDG uncertainty (statistical + systematic combined, as PDG presents it).
- The PDG record URL.
- The PDG edition year (currently 2024; bump when the next review ships).
Example reply:
The Z boson mass is m_Z = 91.1880 ± 0.0020 GeV (PDG 2024).
Source: https://pdg.lbl.gov/2024/listings/rpp2024-list-z-boson.pdf
This skill exists specifically to close the rule 5 loophole. Never quote
a particle constant without running this skill or a comparable tool call.
PDG retrieval
The PDG offers several access surfaces; pick the cheapest that answers the
question:
| Surface | URL pattern | Use for |
|---|
| pdgLive HTML (preferred) | https://pdglive.lbl.gov/ | Interactive listings — WebFetch-friendly HTML; the cheapest reliable surface when it carries the value |
| pdgLive listing pages (PDF) | https://pdg.lbl.gov/2024/listings/rpp2024-list-<particle>.pdf | Full review entries with averages and inputs |
| pdgLive summary tables (PDF) | https://pdg.lbl.gov/2024/tables/rpp2024-sum-<group>.pdf | Quick cross-particle comparisons |
| PDG Booklet PDF | https://pdg.lbl.gov/2024/booklet/rpp2024-booklet.pdf | Bulk reading offline |
| PDG REST API (where available) | https://pdgapi.lbl.gov/... | Programmatic single-value lookup |
Prefer the HTML surfaces (pdgLive, REST API) — they are WebFetch-friendly
and avoid the fragile PDF-extraction path. The rpp2024-list-* / rpp2024-sum-*
links are PDFs (note the .pdf): fall back to them, plus the v1.6.0 PDF
guideline (pdftotext over the listing), only when pdgLive and the REST API
lack the value. The REST API is evolving and not all values are exposed yet.
Common particle URL cheatsheet
(Not the values — the URLs. The values come from a fresh fetch every time.)
| Particle | Listing URL |
|---|
| Z boson | https://pdg.lbl.gov/2024/listings/rpp2024-list-z-boson.pdf |
| W boson | https://pdg.lbl.gov/2024/listings/rpp2024-list-w-boson.pdf |
| Higgs boson | https://pdg.lbl.gov/2024/listings/rpp2024-list-higgs-boson.pdf |
| Top quark | https://pdg.lbl.gov/2024/listings/rpp2024-list-t-quark.pdf |
| Muon | https://pdg.lbl.gov/2024/listings/rpp2024-list-muon.pdf |
| Tau | https://pdg.lbl.gov/2024/listings/rpp2024-list-tau.pdf |
| Pion (π±) | https://pdg.lbl.gov/2024/listings/rpp2024-list-pi-plus-minus.pdf |
| B0 | https://pdg.lbl.gov/2024/listings/rpp2024-list-B0.pdf |
| B± | https://pdg.lbl.gov/2024/listings/rpp2024-list-B-plus-minus.pdf |
For particles not in this cheatsheet, search the PDG index page first:
https://pdg.lbl.gov/2024/listings/contents_listings.html.
Edition bump procedure
When a new PDG Review is published (typically every two years, July):
- Update the year in URL examples above (
2024 → 2026).
- Update the "PDG 2024" citation format string to the new edition.
- Update the description disambiguator if needed.
- Bump VERSION (patch).
