MadGraph5_aMC@NLO is an event generator.
This event generator can do multiple type of computation
- LO cross-section computation and event generation (tree level and loop induced processes)
- NLO fix order computation
- NLO+PS computation (via the MC@NLO method)
Those type of computation are available for the SM and for a large class of model via the UFO format.
The package also include a lot of additional feature
- matrix-element provider (tree level and one loop)
- MadSpin (decay of massive particle in the NWA limit)
- Systematics a code for computation of theoretical uncertainties via re-weighting
- Re-weighting a code to reuse a sample of events (LO OR NLO) and change the weight of each event to predict the shape of a new BSM/SM benchmark
External package can also be interfaced to MadGraph5_aMC@NLO (you can use the "install" command to install those)
- maddm : tools for DM computation (relic density, direct detection,...)
- pythia8 : allow to automatically shower your sample as soon as they are generated
- madanalysis5: analysis and recasting tool
- Delphes: Detector simulation (fast sim)
- ExRootAnalysis: convert your LHE file to root
- NINJA/COLLIER: Additional package to speed up loop computation
The definition of a physical process to generate supports the following syntax, shown by example of the process :
p p > z > e+ e- # requires one s-channel z (but doesn't require it to be on-shell) p p > z, z > e+ e- # on-shell z decaying p p > e+ e- $ z # forbids s-channel z to be on-shell) p p > e+ e- $$ z # forbids any z in s-channel p p > e+ e- / z # forbids any z
Usage in ATLAS
Instructions for using MadGraph5_aMC@NLO in the ATLAS software can be found here (internal).
As MG5_aMC@NLO can run in both LO and NLO modes the naming convention for samples is not entirely obvious. So we make the choice to use the following convention:
- LO process (MadGraph or MG5_aMC@NLO) = "MadGraph" or short "MG"
- NLO process (aMC@NLO or MG5_aMC@NLO) = "aMcAtNlo" or short "aMC"
This convention should be maintained at every stage of the MC production chain – i.e LHE file inputs, JOs, evgenConfig.generators, etc. But it should be noted that the generator should still formally be referred to as MadGraph5_aMC@NLO, the sample naming convention is for our internal ATLAS convenience, to easily distinguish between LO and NLO samples.