liminfoPDG Reference
Free reference guide: PDG Reference
About PDG Reference
The PDG Particle Data Reference is a searchable quick-reference for fundamental particle physics data based on the Particle Data Group (PDG) Review of Particle Physics. It covers leptons (electron, muon, tau, electron neutrino), all six quarks (up, down, strange, charm, bottom, top), baryons (proton, neutron, Lambda, Sigma+, Omega-), mesons (pion+/0, kaon+, J/psi, D0, B+), and gauge bosons (photon, W+/-, Z0, gluon, Higgs).
Each particle entry includes mass (in MeV or GeV), charge, spin, lifetime, primary decay modes with branching ratios, and PDG Monte Carlo ID numbers. This makes it a practical desk reference for particle physicists, graduate students, and anyone studying the Standard Model.
All 26 particles are organized into five categories -- Leptons, Quarks, Baryons, Mesons, and Gauge Bosons -- with instant search and category filtering for fast lookup during calculations, homework, or data analysis.
Key Features
- Lepton data: electron, muon, tau masses, lifetimes, and decay channels with branching ratios
- All six quarks with masses, charges, quantum numbers (isospin, strangeness, charm, bottomness)
- Baryon reference: proton, neutron, Lambda, Sigma+, Omega- with quark compositions and decay modes
- Meson data: pion, kaon, J/psi (charmonium), D0, B+ with lifetimes and dominant decay channels
- Gauge boson properties: photon, W+/-, Z0, gluon, and Higgs boson masses, widths, and decay fractions
- PDG Monte Carlo ID numbers included for every particle for simulation and analysis code
- Neutrino mass upper limits and solar neutrino flux data
- Searchable and filterable across all five particle categories with instant results
Frequently Asked Questions
What particle data does this PDG reference include?
It includes 26 fundamental particles organized by type: 4 leptons (electron, muon, tau, electron neutrino), 6 quarks (up, down, strange, charm, bottom, top), 5 baryons (proton, neutron, Lambda, Sigma+, Omega-), 6 mesons (pion+, pion0, kaon+, J/psi, D0, B+), and 5 gauge bosons (photon, W, Z, gluon, Higgs). Each entry has mass, lifetime, decay modes, and PDG ID.
Where does the particle data come from?
The data is based on the Particle Data Group (PDG) Review of Particle Physics, which is the authoritative compilation of particle physics measurements published by an international collaboration. Values include the most recent measured masses, lifetimes, and branching ratios.
What is the PDG Monte Carlo ID?
The PDG ID is a standardized numbering scheme used in particle physics simulation software (e.g., Pythia, Geant4, HERWIG). For example, electron is 11, up quark is 2, proton is 2212, and Higgs is 25. These IDs are essential for interfacing with Monte Carlo event generators and detector simulations.
What is the mass of the Higgs boson?
The Higgs boson mass is 125.25 +/- 0.17 GeV/c^2 with quantum numbers J^PC = 0^++. Its dominant decay modes are bb-bar (58.2%), WW* (21.4%), gg (8.2%), tau-tau (6.3%), and ZZ* (2.6%), with a total width of approximately 3.2 MeV.
How heavy is the top quark compared to other quarks?
The top quark at 172.69 GeV is by far the heaviest quark -- about 40 times heavier than the bottom quark (4.18 GeV) and roughly 80,000 times heavier than the up quark (2.16 MeV). Its extremely short lifetime (~5x10^-25 s) means it decays before forming hadrons, always via t -> W+ b.
What is the difference between baryons and mesons?
Baryons are made of three quarks (e.g., proton = uud, neutron = udd, Omega- = sss) and have half-integer spin. Mesons are made of a quark-antiquark pair (e.g., pion+ = u d-bar, J/psi = c c-bar) and have integer spin. Both are hadrons bound by the strong force.
Why does the neutron decay but the proton does not?
The free neutron (mass 939.565 MeV) is heavier than the proton (938.272 MeV), so it can decay via n -> p + e- + nu_e-bar with a lifetime of about 878 seconds. The proton is the lightest baryon and baryon number conservation prevents its decay. Experimental bounds put the proton lifetime at >3.6x10^29 years.
Is this PDG reference free to use?
Yes, completely free with no account or download required. All particle data loads in your browser with no server interaction. It is part of liminfo.com's collection of free science and engineering reference tools.