MadGraph5_aMC@NLO

calculation cross section for full process

Asked by Avirup Shaw

I have considered a process is given below,

p p > D+ D-

for one set of parameter xsection is 0.019 pb. and this numer is correct.

Now if we consider the process

p p > D+ D-, D+ > h+ DO, D- > h- DO.

then I have faced some erroneous results. First of all when we consider the process, we allow the decay of D+/D-.
So that I would expect that the number 0.019 should be multiplied by the respective branching fraction. Now in our case, the branching fraction of (D- > h- DO) is almost 100%. so the cross section should be of the order of 0.019. But the actual cross section which I obtained ~ 10^-13 pb. and also this number is vary in different time.

However throughout process madgraph not shown ay kind of error or warning.

So how can I get proper result for the process with longer chain.

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

Are you aware of the following page:
https://answers.launchpad.net/mg5amcnlo/+faq/2442
It contains the most typical reason why you can face such type of problem. So it is likely to contains the solution of your problem.

My best guess in this case, is that your total width is not set correctly in your param_card.

Cheers,

Olivier

> On 17 May 2017, at 10:03, Avirup Shaw <email address hidden> wrote:
>
> New question #632805 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/632805
>
> I have considered a process is given below,
>
> p p > D+ D-
>
> for one set of parameter xsection is 0.019 pb. and this numer is correct.
>
> Now if we consider the process
>
> p p > D+ D-, D+ > h+ DO, D- > h- DO.
>
> then I have faced some erroneous results. First of all when we consider the process, we allow the decay of D+/D-.
> So that I would expect that the number 0.019 should be multiplied by the respective branching fraction. Now in our case, the branching fraction of (D- > h- DO) is almost 100%. so the cross section should be of the order of 0.019. But the actual cross section which I obtained ~ 10^-13 pb. and also this number is vary in different time.
>
> However throughout process madgraph not shown ay kind of error or warning.
>
> So how can I get proper result for the process with longer chain.
>
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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