== Decay Chains  ==



=== People ===
   1. Johan Alwall
   1. Tim Stelzer

=== Aim of the project ===
Allow MadGraph to specify decay chains of the type pp>(t>(W+>e+ve)b)(t~>(W->jj)b~).

=== Tools ===
   * MadGraph

=== Work ===
   * MadGraph: 
      * Implementation of pruning of topologies to speed up process generation for many final state particles
      * Example: pp>(t>(w+>jj)b)(t~>(w->l-vl~)b~): 16 min 15 s with decay chains, 2 h 33 min without decay chains
      * Allow only specified decay chains. Give information on which resonances must be on-shell to MadEvent
      * Allow more than 9 external particles
   * MadEvent: 
      * Read on-shell resonance information to generate only correct diagrams
      * Allow more than 9 external particles

The implementation in MadGraph and MadEvent is completed, but needs to be tested with "real" physics. Still to do is:
   * Diagram drawing for more than 9 external particles
   * Allowing more than 10 external particles in MadGraph

==== Physics results and papers writeup ====
To be decided

-- Main.JohanAlwall - 31 Aug 2007