This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Muon (particle) | |
|---|---|
| Name | Muon |
| Type | Lepton |
| Generation | Second |
| Charge | −1 e |
| Mass | 105.6583745 MeV/c2 |
| Spin | 1/2 |
| Lifetime | 2.1969811 μs |
| Interactions | Electromagnetic, Weak, Gravitational |
Muon (particle) The muon is an elementary Lepton of the second generation, an electrically charged, spin‑1/2 fermion with a mass about 207 times that of the electron and a mean lifetime of ~2.2 microseconds. It participates in electromagnetism and weak processes and plays a central role in experiments at facilities such as CERN, Fermilab, SLAC, KEK and observatories like Super-Kamiokande.
Muons appear in cosmic ray air showers initiated by primary particles interacting with the Upper atmosphere, and are produced abundantly in accelerators including the Proton Synchrotron and the Tevatron. Their existence connects research programs at Brookhaven, LBNL, DESY, TRIUMF, RAL, and experiments such as Muon g−2, MEG, COMET, and Mu2e. Muons serve as probes in studies tied to Standard Model tests, searches connected to Supersymmetry, Dark matter models, and precision measurements relevant to the Weak mixing angle and Quantum electrodynamics.
Muons are members of the lepton family alongside the electron and tau, with associated neutrinos (muon neutrino). Their rest mass is measured precisely at facilities including LEP, ISR, and RHIC, informing calculations in Quantum Field Theory and Quantum Electrodynamics. The muon’s magnetic moment and anomalous magnetic moment link to theoretical work originating from Julian Schwinger, Richard Feynman, Sin-Itiro Tomonaga, and ongoing analyses by collaborations at CERN and Fermilab. Muon spin and parity properties are exploited in experiments at PSI, ISIS, and PSI.
Charged pions produced in collisions at accelerators like CERN SPS and interactions involving cosmic primaries from sources such as Supernova remnants decay into muons via weak processes mediated by W±. Typical production channels include the decay π+ → μ+ + νμ and K+ → μ+ + νμ studied in experiments at NA62, KOTO, and T2K. Muon decay μ− → e− + ν̄e + νμ defines key tests of V–A theory and conservation laws examined by teams at PSI and the ILL. Radiative and rare decays, and lepton flavor violating channels targeted by MEG II, Mu3e, and COMET probe extensions like Leptoquark scenarios and GUT frameworks.
Muon detection techniques are integral to detectors at ATLAS, CMS, LHCb, ALEPH, and neutrino observatories such as IceCube and Super-Kamiokande. Tracking uses chambers including drift chambers, RPCs, CSCs, gas detectors, and silicon layers as deployed in CMS muon systems and ATLAS muon spectrometers. Scintillators, Cherenkov counters, calorimeters, and magnetic spectrometers at Pierre Auger Observatory, MINOS, NOvA, and Soudan Underground Laboratory enable momentum and charge measurements critical to studies performed by collaborations such as IceCube Collaboration and Auger Collaboration.
Muons provide precision tests of the Standard Model, inform determinations of the Fine-structure constant, and constrain models from Supersymmetry to Extra dimensions. Muon tomography, pioneered using principles similar to those in experiments at CERN and industry collaborations, has been applied to imaging at Pyramids of Giza, volcano monitoring at Mount Vesuvius, and cargo scanning for agencies like IAEA. Muon spin rotation and relaxation techniques at Paul Scherrer Institute and ISIS probe materials science problems in superconductors studied at institutes including Max Planck Society, LANL, and ORNL. Muon beams for muon colliders and neutrino factories are under study by consortia such as the Muon Accelerator Program and the MICE.
The muon was discovered in cosmic ray studies by Carl D. Anderson and Seth Neddermeyer in 1936, with confirmations and mass measurements by groups at Rice University, Caltech, Princeton University, and University of Chicago. Its initial identification challenged ideas summarized by Isidor Isaac Rabi with famous remarks linking to the Brookhaven National Laboratory era. Subsequent accelerator experiments at CERN and Fermilab refined muon properties; precision magnetic moment measurements trace to work at Brookhaven National Laboratory and modern efforts at Fermilab.
Muon observables such as the anomalous magnetic moment g−2 have generated tension between experimental results from BNL E821 and Fermilab Muon g-2 and theoretical predictions from collaborations including FLAG, HPQCD, RBC, MILC, and lattice groups at RIKEN. Discrepancies motivate models involving Dark photon portals, Lepton flavor violation mechanisms explored by Belle II and LHCb, and hypotheses from Supersymmetry and Composite Higgs frameworks. Ongoing work by theorists associated with Perimeter Institute, CERN Theory Department, Institute for Advanced Study, and experimentalists at Fermilab, CERN, KEK, and PSI seeks to resolve anomalies via improved lattice QCD, reanalysis of hadronic vacuum polarization, and new precision experiments such as MUonE and upgraded g−2 runs.
Category:Elementary particles