MadGraph5_aMC@NLO

Some Subtle Question on a Matching

Asked by Han

Dear MadGraph team !

I have few questions on a matching.

Q1. What does precisely '@' flag do in the process of matching? Can I just not using '@' flag?

e.g.)
generate p p > z, z > l- l+ @0
add process p p > z j, z > l- l+ @1
add process p p > z j j, z > l- l+ @2

Q2. How can I properly generate the single top production (i.e. z t/t~ + 1,2 jets)? I'm attempting to do in the following way:

define pp = p b b~
generate pp pp > z t j , z > l- l+, (t > w+ b, w+ > j j)
add process pp pp > z t j j , z > l- l+, (t > w+ b, w+ > j j)
add process pp pp > z t~ j , z > l- l+, (t~ > w- b~, w- > j j)
add process pp pp > z t~ j j , z > l- l+, (t~ > w- b~, w- > j j)

The reason why I am asking is that there seems to be an issue on 'special processes, p p > t b~ j + p p > t b~ j j (with 4-flavor matching)' in which matching cannot be done properly. Does this concern apply to my case as well? Then any suggestion for a correct way?

Best Regards

Jeong-han Kim

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MadGraph5_aMC@NLO Edit question
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Solved by:
Olivier Mattelaer
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Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Dear Jeong,

> Q1. What does precisely '@' flag do in the process of matching? Can I just not using '@' flag?

The only impact of the @ is to modify the way the html summary are created. Such that it does automatically the sum of the all the process which are defined with the same @ value.

 > Q2. How can I properly generate the single top production (i.e. z t/t~ + 1,2 jets)? I'm attempting to do in the following way:

In 5 flavor matching, you need also to have the line
define j = pp
(and ensure that maxjetflavor is on 5 in the run_card.
The rest should be fine.

Cheers,

Olivier

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Han (jeonghan-kim) said : 		#2

Thank you so much !