Is a Standard Model interpretation of the Isolated High Energy Lepton   and Missing Transverse Momentum HERA events disfavoured?
  The H1 collaboration has recently reported the observation of events with an isolated high energy lepton and missing transverse momentum. All analysed Standard Model processes were found to fail in explaining the origin of muon events leaving a statistical fluctuation as the only explanation of their appearance. In this paper I discuss mechanisms by which Standard Model processes could either produce or mimic such events and point out several biases of the H1 analysis which led to an underestimation of their contribution. 
M.W. Krasny