== W and H+ polarizations in top decays  ==
   1. Generate %$e^+e^-  \to t \bar t$% at threshold and force the tops to decay leptonically (to %$e$% or %$\mu$%).
      a. Compare the charged and neutral lepton %$p_T$% (or energy) distributions with those shown in the MC lectures.
      a. Explain why the neutrinos tend to have higher %$p_T$% than the charged leptons. 
      a. How would things change if the decay went via %$t\to b H^+$% with %$m_{H^+}=m_W$%? Check by using
          the 2HDM (Use the on-line calculator to get a consistent set of parameters for the 2HDM).
   1. As the previous exercise, but in  %$pp \to t\bar t$% at the LHC. 


-- Main.FabioMaltoni - 06 Dec 2008