Models of Madgraph

Asked by Winston on 2020-03-23

Hi expert,
I am a user of Madgraph. Would you mind I ask you a question about models in Madgrah?
what's the distinguish between models sm, sm_v4, loop_sm and loop_qcd_qed_sm? Look forword your reply.

Best regards,
Renqi Pan

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2020-03-23
Last query:
2020-03-23
Last reply:
2020-03-23

Hi,

sm_v4 is the Standard Model following the Madgraph4 format.
It does not use the ALOHA routine but the HELAS routine for the evaluation of the matrix-element.
This is a quite old format and various functionality of MadGraph5_aMC@NLO will not be supported for this model due to that.

"sm" is the equivalent model but following UFO convention.

loop_sm is the also standard model but it also contains all the information needed to be able to compute loop (in QCD).
loop_qcd_qed_sm is the same but also contains the information for Electroweak loop.

Note that we have put in place automatic model switch from the sm model to either loop_sm or loop_qcd_qed_sm model.
So if you do
import model sm
generate p p > t t~ [QCD]
We will automatically use the loop_sm model.

Cheers,

Olivier

Winston (adampan) said : #2

Thanks Olivier Mattelaer, that solved my question.