Fundamental Muon Physics

Anomalous Magnetic Moment (AMM) of The Muon (Muon g-2)

Magnetic Moment

  • A measure of the strength of a magnetic source
  • The g-factor is a dimensionless quantity that characterizes the magnetic moment and angular momentum of a particle
  • The muon’s spin precesses in the presence of a magnetic field
  • The precession frequency is related to its magnetic moment

Anomalous Magnetic Moment

  • Deviation from Dirac’s prediction for a free lepton (g=2)
  • A contribution of effects of virtual particles, expressed by Feynman diagrams with loops, to the anomalous magnetic moment of muon
  • Precision tests of Standard Model calculations and searches for physics beyond the Standard Model

Related experiments: Fermilab muon g-2 experiment E989, J-PARC muon g-2 experiment, Brookhaven experiment E821

Electric Dipole Moment (EDM) of The Muon (Muon EDM)

Electric Dipole Moment

  • A measure of the charge distribution within a muon.
  • The spin precesses around the direction of the electric field in the presence of a non-zero EDM.
  • This precession frequency is related to its electric dipole moment.
  • A sensitive probe for studying additional sources of charge-parity symmetry breaking.
  • It could shed light on the matter-antimatter asymmetry observed in our universe.

Charged Lepton Flavor Violating (cLFV) Processes

  • Evidence of LFV: neutrinos oscillate
  • Charged lepton flavor violating processes are highly suppressed in the Standard Model
  • A transition between the e, μ, τ sectors that does not conserve lepton family number
  • Total lepton number: L = Le + Lμ+ Lτ
  • To open a unique window on many New Physics (NP) scenarios
  • Related experiments: MEGA experiment, MEG experiment, SINDRUM experiment, SINDRUM II, MEG-II and Mu3e experiments at PSI, Mu2e experiment, COMET/PRISM experiment, DeeMe experiment

Muonic channel: CLFV reactions

References

  1. A. Keshavarzi, K. S. Khaw, T. Yoshioka, Nuclear Physics B, 975 (2022)
  2. K. S. Khaw, A. Adelmann et. al, Search for the muon electric dipole moment using frozen-spin technique at PSI, In Proceedings of the 22nd International Workshop on Neutrinos from Accelerators (2022)
  3. R. H. Bernstein, P. S. Cooper, Charged lepton flavor violation: an experimenter’s guide, Physics Reports, 532, 2 (2013)
  4. W. J. Marciano, T. Mori, J. M. Roney, Charged lepton flavor violation experiments, Annual Review of Nuclear and Particle Science, 58, 1 (2008)