MadGraph5_aMC@NLO

Process involving NP loop in MadGraph

Asked by Dipankar Pradhan

I am trying to generate a process involving a 2 -> 3 process through a box loop where all the couplings are NP. Can MG5 handle NP loops? If yes, how to generate model files for such loop induced NP (similar to loop_qed_qcd_sm)?

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

For loop-induced process, yes this should not be a problem (now this is not tested as far as I know --but for QED loop--).

For the model, you will likely need to write the UFO model by hand (like we did for the loop_qcd_qed_sm model)(please check the UFO2 paper for the details of the syntax and for what is needed).

The main non-trivial part being that you need to compute anylitically all the R2 term for the loop that you consider and put them in the model. Depending of your model, you might also need some UV counter-term but this is quite rare for loop-induced process.

Cheers,

Olivier

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