Puzzle of W Leptonic Decay Branching Fractions and Gauge Model of   Generation Nonuniversality
  Lepton generation universality holds very well in Z decays, but appears to be violated in recent LEP data of W leptonic decay branching fractions. If this trend persists, a consistent and natural explanation is a model of generation nonuniversality, based on the gauge group SU(2)_L X U(1)_R X U(1)_{B-L}. 
Xiao-Yuan Li (ITP Beijing) and Ernest Ma (UC Riverside)