Lepton coupling in the proposed medium interaction and breakdown of muon-electron universality

Abstract

It is argued from analyses of experimental data that the gauge bosons B which mediate the proposed medium interactions may couple to a doublet of the muon and heavy muon but not to the electron. This conjectured μ-B gauge coupling seems to explain the apparent small breakdown of μ-e universality observed in elastic and inelastic $mu$+p scattering and leptonic decay of phi meson. The mass of B is estimated to be around 4 GeV. It is also shown that the anomalous bump (after psi and psi' are subtracted) indicated in muon pair production in high-energy hadron collisions can be explained qualitatively as an effect of muon pair production via a virtual B boson. Several other consequences of the $mu$-B coupling are discussed.