MadGraph5_aMC@NLO

Include ISR in electron ion collider

Asked by Hongkai Liu

Hi,

I want to study the process e- ion > e- ion X. The particle X is produced via photon fusion a a > X.

To achieve this, I generate process: a ion > X ion in the Madgraph v3_2_0 and set set lpp1 = 3 (a from e-) and lpp2 = 0.

According to https://arxiv.org/pdf/2108.10261.pdf, I set pdlabel = isronlyll to include ISR, but zero cross section is returned.

So did I do something essentially wrong or how can I fix this issue?

Best,
Hongkai

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Olivier Mattelaer
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Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

"isronlyll" is only implemented for e+e- collider.
here you can set pdlabel on "none" (maybe only supported since 3.3.0)
or keep the label to the default (nnpdf23lo1).
and you should get the photon from the improved weisiker williams approximation.

You will find more details from this paper:
The Effective Vector Boson Approximation in High-Energy Muon Collisions <https://inspirehep.net/literature/1960240>
but with is detailed in that paper correspond to 3.3.0.

Cheers,

Olivier

> On 29 Nov 2021, at 22:01, Hongkai Liu <email address hidden> wrote:
>
> New question #699677 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/699677
>
> Hi,
>
> I want to study the process e- ion > e- ion X. The particle X is produced via photon fusion a a > X.
>
> To achieve this, I generate process: a ion > X ion in the Madgraph v3_2_0 and set set lpp1 = 3 (a from e-) and lpp2 = 0.
>
> According to https://arxiv.org/pdf/2108.10261.pdf, I set pdlabel = isronlyll to include ISR, but zero cross section is returned.
>
> So did I do something essentially wrong or how can I fix this issue?
>
> Best,
> Hongkai
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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Hongkai Liu (hol42) said : 		#2

Thanks Olivier, I will take a look.

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Hongkai Liu (hol42) said : 		#3

Thanks Olivier Mattelaer, that solved my question.

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Thomas Ingalls (thomasin) said : 		#4

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