Integrated weight and the cross section

Asked by Lailin Xu on 2018-02-13

Hi,

When I run LHE files generation from a gridpack, I find that in the LHE file header, the "Integrated weight" and the cross section number shown in the "<init>" event header are not the same. For example,

<MGGenerationInfo>
# Number of Events : 5500
# Integrated weight (pb) : 0.0985250476819
</MGGenerationInfo>
</header>
<init>
2212 2212 6.500000e+03 6.500000e+03 0 0 262000 262000 -3 1
1.036085e-03 1.538543e-05 1.788850e-05 1
<generator name='MadGraph5_aMC@NLO' version='5.2.4.3'>please cite 1405.0301 </generator>
</init>

The integrated weight is 0.0985250476819, while in "<init>" the cross section is "1.036085e-03".
Do you have any idea why this should happen?
Sorry if I misread the information from the LHE file.

Thanks,
Lailin

Question information

Language:
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Last query:
2018-02-13
Last reply:
2018-02-20

Hi,

I actually do not reproduce this with 2.6.1, so maybe this is something particular to your version.

Other possibiltity, if you have negative PDF, then it is possible thatn the integrated weight is reporting the absolute cross-section
(the one where all contribution are consider as positive)

Cheers,

Olivier

> On 13 Feb 2018, at 14:37, Lailin Xu <email address hidden> wrote:
>
> New question #664348 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/664348
>
> Hi,
>
> When I run LHE files generation from a gridpack, I find that in the LHE file header, the "Integrated weight" and the cross section number shown in the "<init>" event header are not the same. For example,
>
>
> <MGGenerationInfo>
> # Number of Events : 5500
> # Integrated weight (pb) : 0.0985250476819
> </MGGenerationInfo>
> </header>
> <init>
> 2212 2212 6.500000e+03 6.500000e+03 0 0 262000 262000 -3 1
> 1.036085e-03 1.538543e-05 1.788850e-05 1
> <generator name='MadGraph5_aMC@NLO' version='5.2.4.3'>please cite 1405.0301 </generator>
> </init>
>
>
> The integrated weight is 0.0985250476819, while in "<init>" the cross section is "1.036085e-03".
> Do you have any idea why this should happen?
> Sorry if I misread the information from the LHE file.
>
> Thanks,
> Lailin
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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