About Muons

Muon Discovery and its Properties 

  • In the Standard Model, muon is the second generation charged lepton.
  • The muon was discovered in cosmic rays by Anderson and Neddermeyer in 1936 [1].
  • Initially, the muon was mistakenly identified as the Yukawa meson 

Muon and the Weak Interaction 

  • Muons are produced through π , K decay.
  • Muon subsequently decay into an electron and neutrinos. 
  • Weak interaction violates parity.
  • Muons from π , K decay are highly polarized.
  • High-energy electrons are emitted preferably in muon spin direction.
  • The asymmetry of the electrons is energy-dependent. 

Muon and the Building of the Standard Model 

  • The parity problem has been questioned by Lee and Yang [3].
  • The violation was soon observed in the decay of Cobalt-60 and the muon [4].
  • The observation helps establish the V-A theory, a basis for weak interaction in the standard model [5]. 

References

  1. Anderson, C.D. & Neddermeyer, S.H., Phys. Rev. 50, 263 (1936)
  2. Lattes, C., Occhialini, G., Powell, Nature 159, 694-697 (1947)
  3. T.D., Lee & C.N.,Yang, Phys. Rev. 104, 254 (1957)
  4. Garwin, R.L., Lederman, L.M. & Marcel, W., Phys. Rev. 105,1415 (1957)
  5. Roberts, B.L., J. Phys. Soc. Jpn., 76, 111009 (2007)