Mu mesons

The positive muon was discovered in cloud chamber photographs made by C D. Anderson and S.H. Neddermyer on Pike s Peak in 1935, and the negative muon almost simultaneously in cloud chamber photographs made by J.C. Street and E.C. Stevenson. These particles have long been called mu-mesons, but since they are fermions (spin h while all other mesons arc bosons, the name muon is preferred, as is their classification with the leptons because of their small rest mass, which is about 206 mr, where me is the mass of the electron. Another reason is their inability to interact with other particles through the nuclear forces. 

Conditions in the universe almost immediately after the big bang were not favorable for the formation of electrons. At that point in time, gamma rays, photons, and neutrinos had very large amounts of energy, much more than was needed to produce electrons. Instead, conditions favored the creation of much more massive particles with large energy equivalents. Among these particles were the muon and the proton. A muon (also known as a mu meson) is a much more massive relative of the electron. It has amass of 1.870 x 10"25 g, about 2,000 times that of an electron. A proton is even heavier, with a mass of about 1.660 x 10 24 g, nearly 3,000 times that of an electron. 

Muons suffered a similar fate to that of neutrons. A mu meson decays into an electron and two neutrinos with a half-life of only 2.2 x 10-6 second ... 

Anderson, Cari David (1905-91) US physicist who became a professor at the California Institute of Technology, where he worked mainly in particle physics. In 1937 he discovered the "positron in "cosmic radiation, and four years later was awarded the Nobel Prize. In 1939 he discovered the mu-meson (muon). 

Horowitz Murdock [Ho 85] [Mu 87] r-space lA one-meson exchange PV" explicit from one-meson exchange diagram RMF no yes no no... 

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