pdg-lookup

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.

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:

1. The numerical value with units.
2. The PDG uncertainty (statistical + systematic combined, as PDG presents it).
3. The PDG record URL.
4. 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):

1. Update the year in URL examples above (2024 → 2026).
2. Update the "PDG 2024" citation format string to the new edition.
3. Update the description disambiguator if needed.
4. Bump VERSION (patch).