gg -> ta+ ta- j

Hi,

The first think that I need to be sure is which contribution do you want to include in your computation.
Here my understanding is that you are only interested in the loop-induced contribution (the Z diagram can also be generated via quark pair at tree level and I will here remove that contribution).

Removing correctly all the loop related to the tree-level Z diagram is not something trivial that you can do out of the box and you need to hack madgraph in the following way:

=== modified file 'madgraph/loop/loop_diagram_generation.py'
--- madgraph/loop/loop_diagram_generation.py 2017-07-31 12:50:36 +0000
+++ madgraph/loop/loop_diagram_generation.py 2018-02-20 16:49:23 +0000
@@ -384,7 +384,7 @@
         # By default the user filter does nothing if filter is not set,
         # if you want to turn it on and edit it by hand, then set the
         # variable edit_filter_manually to True
- edit_filter_manually = False
+ edit_filter_manually = True
         if not edit_filter_manually and filter in [None,'None']:
             return
         if isinstance(filter,str) and filter.lower() == 'true':
@@ -418,8 +418,8 @@
 # if any([abs(pdg) not in range(1,7) for pdg in diag.get_loop_lines_pdgs()]):
 # valid_diag = False

-# if any([abs(i)!=1000021 for i in diag.get_loop_lines_pdgs()]):
-# valid_diag=False
+ if any([abs(i)==21 for i in diag.get_loop_lines_pdgs()]):
+ valid_diag=False
 # if len(diag.get_loop_lines_pdgs())<4:
 # valid_diag = False

after that change you can do:

generate p p > Z | h > ta+ ta- j [noborn=QCD]

Cheers,

Olivier

> On 20 Feb 2018, at 09:42, shaodingyu <email address hidden> wrote:
>
> New question #664668 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/664668
>
> Dear MG5 authors,
>
> I am trying to generate process gg>ta+ta-j, where I want to include both off-shell processes z*(a*)>ta+ta- and h*>ta+ta-.
>
> The document pro_card.dat is written as
>
> *************************************************
>
> import model loop_sm
> # Define multiparticle labels
> define p = g
> define j = g u c d s u~ c~ d~ s~
> define l+ = e+ mu+
> define l- = e- mu-
> define vl = ve vm vt
> define vl~ = ve~ vm~ vt~
> # Specify process(es) to run
> generate p p > ta+ ta- j [QCD]
> # Output processes to MadEvent directory
> output ggllj
>
> *************************************************
>
> However, the output results don't include h*>ta+ta- channel. If I specify the intermedia states as
>
>
> *************************************************
>
> generate p p > z g > ta+ ta- g [QCD]
> add process p p > h g > ta+ ta- g [QCD]
>
>
> *************************************************
>
> Then I can generate two processes. But the output result looks like it doesn't include interference effects. Do you know how to generate interference for this channel correctly?
>
> Best,
> Dingyu
>
>
>
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