Generating multijet events with met>120 GeV

Asked by HH on 2020-08-24

Dear experts,

Thanks for your good support and MadGraph. In a study I need to analyse p p > j j events with missing Et>120 GeV (as high-level trigger cut). Since the met of most of the events is smaller than 120 GeV, collecting enough number of events is time-consuming. I know that MG provides the possibility for imposing a number of cuts (e.g. misset: minimum missing Et (sum of neutrino's momenta)), however these cuts are imposed in parton-level which (I think) is not effective for multijet events since their missing energy is due to final state neutrinos not parton-level neutrinos.

Q1: I wanted to ask if there is a way to generate p p > j j events with met>120 ?
Q2: If it is not possible to impose a met>120 cut at parton-level, is it possible for MG to impose met>120 after showering and before delphes simulation? I mean, can MG impose such cuts at showering level and veto events with lower met?

Thanks in advance for you help

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2020-09-05
Last query:
2020-09-05
Last reply:
2020-09-01

Hi,

Q1: I wanted to ask if there is a way to generate p p > j j events with met>120 ?

No we can not (at the level of MG5aMC) impose cut on missing-et (since at our level met is always zero so you either cut the full signal or nothing).

Q2: If it is not possible to impose a met>120 cut at parton-level, is it possible for MG to impose met>120 after showering and before delphes simulation? I mean, can MG impose such cuts at showering level and veto events with lower met?

We do not have any filtering step in place between the parton-shower and Delphes. So no.
Now I would be surprised if most of the parton-shower does not have a way to filter event on the flight. (at worse via a plugin/hook method) For that you would need to refer to the manual of the parton-shower that you are using.

Cheers,

Olivier

HH (hh-madgrapher) said : #2

Thanks Olivier Mattelaer, that solved my question.