Introducing Mad Graph II Automated TreeLevel Feynman Diagram

Introducing Mad. Graph II + Automated Tree-Level Feynman Diagram and Helicity Amplitude Generation

Outline • • • What is Mad. Graph? What’s New in Mad. Graph II? Why use Mad. Graph? Example: Top production at FNAL Future Plans

What is Mad. Graph? • 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.

What’s New in Mad. Graph II? • User defined models – Standard Model – MSSM • Unlimited external particles – Within reason! (12? ) • Color Flow Information – Helps interface with HERWIG/PYTHIA • Required/Excluded particles – uu~ > W+ W- b b~ g – uu~ > tt~ >W+ W- b b~ g // Z

Why use Mad. Graph? • User interface ………NOT • Powerful (Lots of diagrams/external particles) • Relatively fast – Amplitude generation – Matrix element evaluation a N not N 2 • Keeps Spin Information – Easy to add decay chains

Top Pairs at Fermilab • Signal uu~ > tt~ > e+ ve b e- ve~ b~ • Background: uu~ > e+ ve b e- ve~ b~ • Radiation: uu~ > tt~ > e+ ve b e- ve~ b~ g

Signal (1) uu~ > tt~ > e+ ve b e- ve~ b~

Diagrams Feynman Background (66)

Signal+Radiation (7)

Future of Mad. Graph • Tell me what you want! • Improved Interface – User – PYTHIA/HERWIG – Integration • Improved Speed