Gluon Gluon Fusion cross-section for Higgs Production with 'heft' model

Asked by Samadrita Mukherjee


I am trying to generate a process for the production of the Higgs boson with ggF using the 'heft' model.

I am using the following commands in Madgraph_v3.1.1

import model heft --modelname
generate g g > h
output test_ggh_heft

and using the default param_card and run_card at 13 TeV, I get the cross-section 17.62 pb.

Now following the link, we know that Higgs production cross-section through ggF is ~ 48.5 pb at N3LO etc.....

my question is how to get the ggF cross-section close to this actual number in Madgraph.

I tried with g g > h [QCD], but the 'heft' model does not support NLO calculations.

Thanks for any help.


Question information

English Edit question
MadGraph5_aMC@NLO Edit question
No assignee Edit question
Last query:
Last reply:
Revision history for this message
Samadrita Mukherjee (samadritamisti) said :


I am also trying these things with 'loop_sm' model in MG5.

There it is showing the following error for g g > h [QCD] process:


MG5_aMC>import model loop_sm --modelname
INFO: Restrict model loop_sm with file models/loop_sm/restrict_default.dat .
INFO: Run "set stdout_level DEBUG" before import for more information.
Kept definitions of multiparticles p / j / l+ / l- / vl / vl~ unchanged
Defined multiparticle all = g gh gh~ d u s c d~ u~ s~ c~ a ve vm vt e- m- ve~ vm~ vt~ e+ m+ b t b~ t~ z w+ h w- tt- tt+
MG5_aMC>generate g g > h [QCD]
INFO: Checking for minimal orders which gives processes.
INFO: Please specify coupling orders to bypass this step.
INFO: Trying coupling order WEIGHTED<=2: WEIGTHED IS QCD+2*QED
INFO: Trying coupling order WEIGHTED<=3: WEIGTHED IS QCD+2*QED
Error detected in "generate g g > h [QCD]"
write debug file MG5_debug
If you need help with this issue please contact us at
str :
 Automatic process-order determination lead to negative constraints:
 QED: 3, QCD: -2
 Please specify the coupling orders from the command line.


Consulted the slides found here :

It says that the process g g > h [QCD] should work and also giving the cross-section at the ballpark of 15-17 pb.

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said :


Since 3.0.0 for loop-induced you need to specify a coupling order to have it working
generate g g > h qed<=1 [QCD]

Now in the loop-sm model, you have massive b and therefore you will include the (negative b-t) interference
and your cross-section will be slightly smaller than if you do not include that contribution (like using loop_sm-no_b_mass)
The prediction for loop_sm-no_b_mass should match the one of the heft model

This process has been used to validate the implementation of the loop-induced processes within mG5aMC, so you will have all the details in the loop-induced paper: 1507.00020



PS: The Higgs production is know to have very (very) large K-factor (even larger than naive scale variation) both from LO to NLO and also from NLO to NNLO. Therefore since all the computation done at loop-induced level (or at tree level within heft) under-estimate the total cross-section by large number. Consequently, such type of simulation should not be used for the normalization but rather for the shape of the distribution where error / impact of higher order are milder.

Revision history for this message
Samadrita Mukherjee (samadritamisti) said :

Thanks for the detailed explanation and for the reference 1507.00020.

But when I am trying to use:

g g > h qed<=1 [QCD]

it gives the following error:

MG5_aMC>generate g g > h QED<=1 [QCD]
Command "generate g g > h QED<=1 [QCD]" interrupted with error:
Exception : Potentially ambigious syntax detected. Note that the syntax of paper 1804.10017 (used in 3.0.x) is not used anymore (since version 3.1.0).
 If you want to follow the syntax of that paper, you can just replace "QED" by "aEW" and "QCD" by "aS".
 More information here:
 If you know the current meaning of the syntax you can bypass this crash by running (once per machine) this command:
  set acknowledged_v3.1_syntax True --global
Please report this bug on
More information is found in 'MG5_debug'.
Please attach this file to your report.

tried with 'QED', 'aEW', 'aS', but didn't work.

Can you please suggest which model to import to do such!


Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said :

you can either run
set acknowledged_v3.1_syntax True --global
(you need to run that command only once)
and then reuse the above command

or move to
generate g g > h QED<=1 [noborn=QCD]



Revision history for this message
Samadrita Mukherjee (samadritamisti) said :

Thanks a lot. It worked.

Can you help with this problem?

Provide an answer of your own, or ask Samadrita Mukherjee for more information if necessary.

To post a message you must log in.