1. MadGraph/MadEvent 4.0 SUSY, 2HDM and more
Johan Alwall Center for Particle Physics and Phenomenology (CP3), Université Catholique de Louvain
Fabio Maltoni (UCL)
Tim Stelzer (UIUC)
Simon de Visscher (UCL)
Rikkert Frederix (UCL)
Michel Herquet (UCL)
Charged 2006, Uppsala, Sweden, 15 September 2006

2. What is MadGraph/MadEvent?
Given any* process, generates Feynman diagrams, cross-section and events
New models (previously only SM)
SUSY, 2HDM and Higgs EFT
Framework for easy implementation of new models
Web-based generation (no need for Fortran compiler!) or download code
Pythia and detector simulation packages for complete event simulation on-line
Three clusters (UIUC, Rome and UCL)
* Within reason
September
Johan Alwall - MadGraph/MadEvent 4.0

3. Johan Alwall - MadGraph/MadEvent 4.0
How MG/ME works
MadGraph:
Generates all possible Feynman diagrams for a process using info from particles.dat and interactions.dat
Generates Fortran file with HELAS (Helicity ampliude library) calls for the matrix element of the process
Keeps full spin correlations / interference throughout
MadEvent:
Integrates cross-section and produces weighted/unweighted events using the Single diagram enhanced multichannel integration technique
Method parallell in nature – optimal for clusters!
September
Johan Alwall - MadGraph/MadEvent 4.0

4. MG/ME 4 generation structure
Calculator
banner
proc_card
param_card
run_card
pythia_card
pgs_card MG ME
Pythia
PGS
Emph. more independance of each block
Feyn. diags.
HELAS
amplitudes
Parton-level events
Root-file
Plots
Hadron-level
events
Reconstructed
events
Root-file
September
Johan Alwall - MadGraph/MadEvent 4.0

5. New models: MSSM CP- and R-parity conserving MSSM
Hagiwara, Kaoru, Plehn, Rainwater, Stelzer + Alwall
CP- and R-parity conserving MSSM
SUSY Les Houches input files – independent of SUSY breaking scheme
Using Calculator to get consistent calculations of dependent SM parameters and decay widths
Detailed comparison of cross sections for more than 500 processes between SMadGraph, Omega and Amegic++ (hep-ph/ )
Input files for the 10 Snowmass benchmark points available on the web page
September
Johan Alwall - MadGraph/MadEvent 4.0

6. Studies done with SMadGraph
Comparison with Pythia: Squarks/gluinos+jets Plehn, Rainwater, Skands (hep-ph/ ) Matrix element g ̃g ̃+2j and g ̃u ̃L+2j against Pythia showers
SUSY easier than tops! QCD – the heavier the bettter!
September
Johan Alwall - MadGraph/MadEvent 4.0

7. Studies done with SMadGraph
Gluino spin determination Compare with “bosonic SUSY” Universal extra dimensions Alves, Eboli, Plehn (hep-ph/ ) (many ideas: Smillie & Webber)
– gluino decay chain as for mass measurement
– compare with first KK g, q, Z, and l
– decay asymmetr y b vs. b ̄ [instead of near/far b]
– Pure jet obser vables which work:
– Obviously need full spin correlations throughout decay chain
Gluino spin sits in decay kinematics
September
Johan Alwall - MadGraph/MadEvent 4.0

8. Johan Alwall - MadGraph/MadEvent 4.0
General 2HDM
de Vissher, Herquet
Completely general 2HDM, with FCNC and CP violation
New tree-level calculator with a web interface, TwoHiggsCalc, to generate the LHA-like param_card
Tested in the SM & MSSM limit
Also simplified version without FCNC and off-diagonal CKM
Sample files including: SM limit, MSSM, type I, II, III, CP viol.,...
September
Johan Alwall - MadGraph/MadEvent 4.0

9. Johan Alwall - MadGraph/MadEvent 4.0
TwoHiggsCalc
Herquet
Tree level parameter calculator for the general 2HDM written in C.
Starting from Lagrangian parameters, performs numerical computations to minimize the potential and extract relevant parameters for ME: masses, widths, couplings and mixings, as well as BRs that can be useful for cross checking results.
Unusual cases (explicit CP violation, FCNCs, ...) are covered.
Conversion from any basis to Higgs basis via invariants (see hep-ph/ )
Input and output files similar to the SUSY Les Houches format.
Parameter space can be scanned automatically to produce sets of param_card.
September
Johan Alwall - MadGraph/MadEvent 4.0

10. Johan Alwall - MadGraph/MadEvent 4.0
TwoHiggsCalc
September
Johan Alwall - MadGraph/MadEvent 4.0

11. Johan Alwall - MadGraph/MadEvent 4.0
Higgs EFT & User model
Higgs Effective Theory (Frederix)
Effective couplings of (scalar and pseudoscalar) Higgs to gluons
User model (de Visscher)
General framework for user-defined models
User only needs to introduce the new particles, new interactions, new parameters and new couplings. A Perl script takes care of the rest!
Used by Pierce et al. in simulation of higher-order operators in Higgs pair production (hep- ph/ )
September
Johan Alwall - MadGraph/MadEvent 4.0

12. Johan Alwall - MadGraph/MadEvent 4.0
Work in progress
More models: UED (Alves), Technicolor (Gudnason), ...
Specification of complete decay chains
Allows for large number of final state particles
Still keeps full spin correlations
Automatic matching of matrix elements and parton showers (Alwall - Höche)
Using CKKW and MLM schemes
Automatic width calculator for new models
Matrix element techniques for signal selection
September
Johan Alwall - MadGraph/MadEvent 4.0

13. Johan Alwall - MadGraph/MadEvent 4.0
Conclusion
MadGraph/MadEvent 4.0 is available now!
Key points of its philosophy:
Multi purpose : signal + background with same tool; new models easy to implement, and several already there (MSSM, 2HDM, Higgs EFT, ...)
Complete : from model to detector in one run
User friendly : on-line or downloaded
Fast : thanks to parallelized, cluster oriented generation
Portable : easily install on new clusters from CVS
Open : LHA and LHEF compliant, interfaces for Pythia, PGS, Root, Herwig ...
September
Johan Alwall - MadGraph/MadEvent 4.0

14. Johan Alwall - MadGraph/MadEvent 4.0
Try it out
Clusters found at:
UCL:
Rome:
UIUC: (still version 3)
Registration for on-line process generation is quick and automatic
To do on-line event generation – send us a mail!
We are continually improving MadGraph/MadEvent, grateful for all feedback!
September
Johan Alwall - MadGraph/MadEvent 4.0

15. Johan Alwall - MadGraph/MadEvent 4.0
Backup slides
September
Johan Alwall - MadGraph/MadEvent 4.0

16. Johan Alwall - MadGraph/MadEvent 4.0
The cards
pp > W+jjj
QCD=3
QED=1 sm
The proc_card:
Defines the process(es), order in couplings and model.
The param_card:
Defines the model parameters (masses, widths and couplings) in SUSY Les Houches-like format
The run_card:
Defines the collider, cuts, parton densities and scales
The pythia_card and pgs_card determine the operation of Pythia and PGS.
Block MASS
E+00
1 = lpp1 ! beam 1 type
1 = lpp2 ! beam 2 type
7000 = ebeam1 ! beam 1 energy
7000 = ebeam2 ! beam 2 energy
September
Johan Alwall - MadGraph/MadEvent 4.0

17. Particles and interactions
September
Johan Alwall - MadGraph/MadEvent 4.0

18. Johan Alwall - MadGraph/MadEvent 4.0
Matching of ME and PS
MLM-like with Pythia showers (Alwall) (Sudakov suppression from parton showers)
CKKW-like with Sherpa showers (Höche - Alwall) (analytic Sudakovs)
September
Johan Alwall - MadGraph/MadEvent 4.0

19. Johan Alwall - MadGraph/MadEvent 4.0
Results of the web run
September
Johan Alwall - MadGraph/MadEvent 4.0

20. Johan Alwall - MadGraph/MadEvent 4.0
Results of the web run 2
September
Johan Alwall - MadGraph/MadEvent 4.0