Events in interference processes

Asked by daniel camargo on 2018-07-30

Hey guys,

I´m generating p p > l- l+ QED=2 where there is an extra Z´ (I want to see interference effects...). I expect the invariant mass mll contain 2 approximate resonances at the Z and Z´ masses, but it just generate the one of Z, and no events left for Z´. What I am missing here in order to see both resonances?

Thanks in advance!

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2018-08-01
Last query:
2018-08-01
Last reply:
2018-07-31

Hi,

> What I am missing here in order to see both resonances?

Well to give us the full information about what you try such that we can do something more than just speculate.
So here is wild guess
1) what is the mass of the Z'
2) what is the cross-section for the Z (alone)
3) what is the cross-section for the Z' (alone)
4) what is the cross-section for the sum of the two (with interference)

Cheers,

Olivier

> On 30 Jul 2018, at 22:07, daniel camargo <email address hidden> wrote:
>
> New question #671236 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/671236
>
> Hey guys,
>
> I´m generating p p > l- l+ QED=2 where there is an extra Z´ (I want to see interference effects...). I expect the invariant mass mll contain 2 approximate resonances at the Z and Z´ masses, but it just generate the one of Z, and no events left for Z´. What I am missing here in order to see both resonances?
>
> Thanks in advance!
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

daniel camargo (dacamargov) said : #2

hey Oliver,

1) what is the mass of the Z'
> ~TeV scale (1-3 TeV).

2) what is the cross-section for the Z (alone)
> 1201 (pb)

3) what is the cross-section for the Z' (alone)
>for mz´ = 1 TeV, sigma = 0.008833 (pb)

4) what is the cross-section for the sum of the two (with interference)
>for mz´ = 1 TeV , sigma=1660 (pb)

Thanks

Ok so how many events did you generate? You will need a huge amount of event in order to see a z prime due to the ratio of cross section

Cheers

Olivier

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________________________________
From: <email address hidden> <email address hidden> on behalf of daniel camargo <email address hidden>
Sent: Tuesday, July 31, 2018 6:22:28 PM
To: Olivier Mattelaer
Subject: Re: [Question #671236]: Events in interference processes

Question #671236 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/mg5amcnlo/+question/671236

daniel camargo posted a new comment:
hey Oliver,

1) what is the mass of the Z'
> ~TeV scale (1-3 TeV).

2) what is the cross-section for the Z (alone)
> 1201 (pb)

3) what is the cross-section for the Z' (alone)
>for mz´ = 1 TeV, sigma = 0.008833 (pb)

4) what is the cross-section for the sum of the two (with interference)
>for mz´ = 1 TeV , sigma=1660 (pb)

Thanks

--
You received this question notification because you are an answer
contact for MadGraph5_aMC@NLO.

daniel camargo (dacamargov) said : #4

100k events, I guess more than that is not recommendable per-run right?

Cheers,

Ok in a sample of 100k events, you expect in average ~ 1 events to be from the Z prime peak.
So if you do not see any of those, this should not be a problem in itself. Now if you do not see any of those in 25 different samples, then this is a sign of a bug.

This being said, you can actually generate larger sample without any problem.

Cheers,

Olivier

daniel camargo (dacamargov) said : #6

Thanks Olivier Mattelaer, that solved my question.