discrepancy in cross-sections for ggF Higgs production

Hi,

The result provided by MG5aMC is the LO results (with full top mass), while the result that you quote is likely to be the N^3LO (assuming infinite top mass).

Cheers,

Olivier

> On 5 May 2017, at 12:43, liuwei <email address hidden> wrote:
>
> New question #631240 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/631240
>
> I use the loopsm model to simulate ggF of a 125 GeV Higgs with the syntax g g > H [QCD]. From the LHC yellow book I expect a value around 19 pb at sqrt(s)=8 TeV. However, what I obtain is ~7 pb. Do you know why this discrepancy appears? I did not modify any kinematical cuts. Actually I know the scales affect the result, so I set all of them equal to 125 GeV. And I choose cteq6l1 PDF set.
>
> #*********************************************************************
> # Renormalization and factorization scales *
> #*********************************************************************
> True = fixed_ren_scale ! if .true. use fixed ren scale
> True = fixed_fac_scale ! if .true. use fixed fac scale
> 125 = scale ! fixed ren scale
> 125 = dsqrt_q2fact1 ! fixed fact scale for pdf1
> 125 = dsqrt_q2fact2 ! fixed fact scale for pdf2
> -1 = dynamical_scale_choice ! Choose one of the preselected dynamical choices
> 1.0 = scalefact ! scale factor for event-by-event scales
> ******************************************************************
> cteq6l1 = pdlabel ! PDF set
>
> --
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> contact for MadGraph5_aMC@NLO.

Hi Olivier,
So now I understand this difference, but how can I manage to get this number to become 19pb ?

Best
Wei Liu

Thanks Olivier Mattelaer, that solved my question.