# Individual cross section and corresponding diagram

Dear MG authors:

After calculating the cross section for some process, I want to have a check in the "HTML/run_

However, for 'a a > h+ h-', in the matrix1.ps, the diagram1 comes from four-point vertex. However, I don't see the assignment of diagram 1 to any GXX. Thus I would like to ask How such diagram is assigned? (For e- e+ > e- e+ h+ h-, I also don't see the assignment of the diagrams involving four-point vertex to any GXX)

Further, I also would like to know more detail about GXX, as I can see like G1xxx, or G1.02 etc, what does this mean? Thanks!

Best

Ted Wu

## Question information

- Language:
- English Edit question

- Status:
- Solved

- Assignee:
- No assignee Edit question

- Solved by:
- Olivier Mattelaer

- Solved:
- 2020-09-10

- Last query:
- 2020-09-10

- Last reply:
- 2020-09-05

Hi,

The document about this is here:

https:/

> However, for 'a a > h+ h-', in the matrix1.ps, the diagram1 comes from four-point vertex. However, I don't see the assignment of diagram 1 to any GXX. Thus I would like to ask How such diagram is assigned? (For e- e+ > e- e+ h+ h-, I also don't see the assignment of the diagrams involving four-point vertex to any GXX)

Four point diagram are by default not used for the channel of integration so indeed you will never have a channel GXXX associated to them. (the only case where this is not the case is if they are no diagram with only 3-point vertex.

> Further, I also would like to know more detail about GXX, as I can see like G1xxx, or G1.02 etc, what does this mean? Thanks!

The presence of .XX or .XXX means that madgraph identifies a breitwigner conflict in that channel of integration. The channel is then split in 3^N pieces (where N is the number of particles in breitwigner conflict)

and the value XX or XXX correspond to a ternary encoding of which particle is assume to be below his onshell mass, onshell or above his onshell mass.

Cheers,

Olivier

> On 5 Sep 2020, at 02:25, teddym <email address hidden> wrote:

>

> New question #692757 on MadGraph5_aMC@NLO:

> https:/

>

> Dear MG authors:

> After calculating the cross section for some process, I want to have a check in the "HTML/run_

>

> However, for 'a a > h+ h-', in the matrix1.ps, the diagram1 comes from four-point vertex. However, I don't see the assignment of diagram 1 to any GXX. Thus I would like to ask How such diagram is assigned? (For e- e+ > e- e+ h+ h-, I also don't see the assignment of the diagrams involving four-point vertex to any GXX)

>

> Further, I also would like to know more detail about GXX, as I can see like G1xxx, or G1.02 etc, what does this mean? Thanks!

>

>

> Best

> Ted Wu

>

> --

> You received this question notification because you are an answer

> contact for MadGraph5_aMC@NLO.

teddym (niepanchongsheng) said : | #2 |

Hi Olivier:

Thanks for your answer.

> Four point diagram are by default not used for the channel of integration so indeed you will never have a channel GXXX associated to them. (the only case where this is not the case is if they are no diagram with only 3-point vertex.

Then, Does that mean I can't get a rough idea of what is the contribution from those four point diagrams? And since the sum of all GXX are the total cross section, I even can't have a rough sense of what are the contributions from other diagrams, as the four-point diagram is hidden behind that.

Thanks

Ted Wu

Yes,

Those number are not the contribution of a given diagram. They are linked to them but not in a trivial way.

Cheers,

Olivier

> On 5 Sep 2020, at 16:55, teddym <email address hidden> wrote:

>

> Question #692757 on MadGraph5_aMC@NLO changed:

> https:/

>

> Status: Answered => Open

>

> teddym is still having a problem:

> Hi Olivier:

> Thanks for your answer.

>

>> Four point diagram are by default not used for the channel of

> integration so indeed you will never have a channel GXXX associated to

> them. (the only case where this is not the case is if they are no

> diagram with only 3-point vertex.

>

> Then, Does that mean I can't get a rough idea of what is the

> contribution from those four point diagrams? And since the sum of all

> GXX are the total cross section, I even can't have a rough sense of what

> are the contributions from other diagrams, as the four-point diagram is

> hidden behind that.

>

>

> Thanks

>

> Ted Wu

>

> --

> You received this question notification because you are an answer

> contact for MadGraph5_aMC@NLO.

teddym (niepanchongsheng) said : | #4 |

Thanks Olivier Mattelaer, that solved my question.