{
  "metadata": {
    "source": "Particle Data Group",
    "year": 2025,
    "url": "https://pdg.lbl.gov",
    "version": "2025.1",
    "last_updated": "2025-07-01"
  },
  "particles": {
    "W": {
      "mass": {
        "value": 80.377,
        "stat_error": 0.012,
        "sys_error": 0.000,
        "unit": "GeV"
      },
      "width": {
        "value": 2.085,
        "error": 0.042,
        "unit": "GeV"
      }
    },
    "Z": {
      "mass": {
        "value": 91.1876,
        "error": 0.0021,
        "unit": "GeV"
      },
      "width": {
        "value": 2.4952,
        "error": 0.0023,
        "unit": "GeV"
      }
    },
    "Higgs": {
      "mass": {
        "value": 125.20,
        "error": 0.11,
        "unit": "GeV"
      },
      "width": {
        "value": 0.00407,
        "error": 0.00016,
        "unit": "GeV"
      }
    },
    "top": {
      "mass": {
        "value": 172.57,
        "stat_error": 0.29,
        "sys_error": 0.00,
        "unit": "GeV"
      }
    },
    "electron": {
      "mass": {
        "value": 0.51099895000,
        "error": 0.00000000015,
        "unit": "MeV"
      }
    },
    "muon": {
      "mass": {
        "value": 105.6583755,
        "error": 0.0000023,
        "unit": "MeV"
      },
      "lifetime": {
        "value": 2.1969811e-6,
        "error": 0.0000022e-6,
        "unit": "s"
      }
    },
    "tau": {
      "mass": {
        "value": 1776.86,
        "error": 0.12,
        "unit": "MeV"
      }
    }
  },
  "constants": {
    "alpha_em": {
      "value": 0.0072973525693,
      "error": 0.0000000000011,
      "description": "Fine structure constant"
    },
    "G_F": {
      "value": 1.1663787e-5,
      "error": 0.0000006e-5,
      "unit": "GeV^-2",
      "description": "Fermi coupling constant"
    },
    "sin2_theta_W": {
      "value": 0.23122,
      "error": 0.00003,
      "description": "Weak mixing angle (MS-bar scheme)"
    }
  }
}