MadGraph5_aMC@NLO

Generate Signal events only

Asked by Daniel Schieber

Hello,
I'm currently working on extended Higgs models N2HDM and 2HDMS and the Trilinear Higgs coupling in e+ e- colliders.
I am currently generating events "e+e- > z h h" which contains the signal "e+e- > z h > z h h" with the THC and the background "e+e- > z h h /h" In the Models it gets more complicated with the h1 h2 and h3. I want to analyse the cross-sections combined and separated. Therefore, i use add process. However, as a check i tested what happens if i generate the process
"e1 e1bar > z h2 h2 /ah2 e1 e2 e3 e1bar e2bar e3bar", separately and add them together (See below), the cross-sections differs, because it is not taking the Interference into account. So my question is, is there a way to add processes with the same final state, but also considering the interference. For example: I want to generate "e1 e1bar > z hi > z h2 h2" where hi = h1, h2 or h3 and with the Interference. I tried "define multiparticle h = h1 h2 h3" But it did not worked in the generation. Maybe someone can help me with that? I'm rather new to MadGraph.

Daniel

import model N2HDM -modelname
generate e1 e1bar > z h1 > z h2 h2 /ah2 e1 e2 e3 e1bar e2bar e3bar
add process e1 e1bar > z h2 > z h2 h2 /ah2 e1 e2 e3 e1bar e2bar e3bar
add process e1 e1bar > z h3 > z h2 h2 /ah2 e1 e2 e3 e1bar e2bar e3bar
add process e1 e1bar > z h2 h2 /ah2 e1 e2 e3 e1bar e2bar e3bar h1 h2 h3
output /home/documents/master_thesis/mg5_runs/mg5_analysis/eezhh_NTHDM_TEST

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Solved by:
Olivier Mattelaer
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Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

No we do not have syntax to add process with interference.
The way to do it is then to generate all diagrams and then write a python routine that select the diagram that you want to keep
(see https://answers.launchpad.net/mg5amcnlo/+faq/3322)

maybe another option is to use the "or" multiparticles:
generate e1 e1bar > z h1 | h2 | h3 > z h2 h2 /ah2 e1 e2 e3 e1bar e2bar e3bar

So this require that you have (at least) one S-channel propagator with a Z and a second S-channel propagator which is either h1, h2 or h3.

Cheers,

olivier

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Daniel Schieber (themaker845) said : 		#2

Thanks Olivier Mattelaer, that solved my question.

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Jyotiranjan (jyotiranjan-beuria) said : 		#3

Hello Daniel and Olivier,

Where can I find the model files for N2HDM and 2HDMS?

Best regards
JB

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Daniel Schieber (themaker845) said : 		#4

Hello JB,

I got my model files from my supervisor. Also, my 2HDMS has an additional Z3 symmetry.
However, I think they used SARAH (https://sarah.hepforge.org/) to generate the model files (UFO files) for MadGraph5.
I do not know how to do that, though, but there should be a documentation.

Daniel

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Jyotiranjan (jyotiranjan-beuria) said : 		#5

Okay, thanks