MadGraph + MadEvent Automated Tree-Level Feynman Diagram, Helicity Amplitude, and Event Generation + Tim Stelzer Fabio Maltoni

Outline What is MadGraph? What’s New in MadGraph II? Example: W+ 3 jets FNAL What is MadEvent? Capability Future

What is MadGraph? Fortran computer program that: –Generates fortran helicity code (HELAS) to calculate tree level matrix elements –Includes color/symmetry factors –Creates postscript file of Feynman diagrams.

New in MadGraph II! User defined models –Standard Model –MSSM Unlimited external particles –Within reason! (12?) Color Flow Information –Helps interface with HERWIG/PYTHIA Jets + Required/Excluded particles –pp ~ > W+ W- b b~ j –pp~ > tt~ >W+ W- b b~ j // Z Phase Space Information

PP → W + 3 jets Enter Process: pp > e+ ve jjj Enter QCD Order: 4 Enter QED Order: 2 (…… wait 2 minutes) Generated 53 sub processes

What is MadEvent? Fortran computer program that: –Uses output from MadGraph –Generates Cross sections Events (Les Houche format) –W + 3 jets: First 10,000 unweighted events about 30 minutes.

Examples: Vector Bosons

Examples: Heavy Quarks

What about W+8 jets? Current Limitations –PP -> W + 5 jets (1 week) – 9999 diagrams (1000 is nice) –10 external particles (8 is easy) –7 summed particles (protons/jets) Future Improvements –Housekeeping –Phase Space (factor of 10 in speed!)