Cross section of madgraph higgs production

Asked by Ta'el Coren on 2019-06-03

Dear Madgraph team.
I'm currently trying to simulate higgs production (gloun-gloun fusion) by using the model heft.
When I generate the process (generate P P > H) I get a production cross section of 17.62 ipb.
Comparing this to the CERN yellow pages, which is 43.92 ipb at a center of mass energy of 13 TeV, there is a factor of 2.5 difference between the two.
What is the source of this discrepancy? Is it because the yellow pages compute it at NNLO while madgraph works at LO?
How do I go about solving this issue? Is there a way to get the correct cross section from MadGraph, or should I just scale the events (give them appropriate weights) to match the cross section from the literature?

Thank you for the help
-Ta'el Coren

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2019-06-04
Last query:
2019-06-04
Last reply:
2019-06-03

Hi,

It is well known that the LO cross-section for this process under-estimates a lot both the central value but also the theoretical uncertainties.
This being said using heft introduces additional approximation:
1) the bottom quark loop is not included in the computation (including it decreases even more the LO cross-section actually)
2) you can not describe any kinematics where scale is higher than the top quark mass (which is fine for p p > h at LO)

But yes, you will have to scale the weights in this case.

Cheers,

Olivier

> On 3 Jun 2019, at 15:57, Ta'el Coren <email address hidden> wrote:
>
> New question #681212 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/681212
>
> Dear Madgraph team.
> I'm currently trying to simulate higgs production (gloun-gloun fusion) by using the model heft.
> When I generate the process (generate P P > H) I get a production cross section of 17.62 ipb.
> Comparing this to the CERN yellow pages, which is 43.92 ipb at a center of mass energy of 13 TeV, there is a factor of 2.5 difference between the two.
> What is the source of this discrepancy? Is it because the yellow pages compute it at NNLO while madgraph works at LO?
> How do I go about solving this issue? Is there a way to get the correct cross section from MadGraph, or should I just scale the events (give them appropriate weights) to match the cross section from the literature?
>
> Thank you for the help
> -Ta'el COren
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Ta'el Coren (tcoren) said : #2

Thanks Olivier Mattelaer, that solved my question.