Heavy ion beams at NLO

Asked by Skelas on 2020-03-23

Hello!

I want to know if it is possible to specify heavy ion beams, i.e. beams with protons and neutrons, for NLO calculations?

The "update ion_pdf" options for updating run_card.dat, which is available for LO calculations, does not work when calculating NLO processes.

Thanks!
Aleksas

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Last query:
2020-03-23
Last reply:
2020-03-23

Hi,

This is not implemented.
I believe that implementing Lead-Lead collision should be possible and easy.
However assymetric beams are likely very difficult to do.

Cheers,

Olivier

> On 23 Mar 2020, at 22:09, Skelas <email address hidden> wrote:
>
> New question #689460 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/689460
>
> Hello!
>
> I want to know if it is possible to specify heavy ion beams, i.e. beams with protons and neutrons, for NLO calculations?
>
> The "update ion_pdf" options for updating run_card.dat, which is available for LO calculations, does not work when calculating NLO processes.
>
> Thanks!
> Aleksas
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Skelas (aleksasmaz-gmail) said : #2

Dear Olivier,

Thanks for the quick reply. I would be happy to have at least symmetric beams. Can you point me to what should be done to port heavy ion functionality from LO to NLO?

I think the bare minimum what I need are the calculations for proton-proton, proton-neutron and neutron-neutron collisions. Maybe it is as simple as telling aMC@NLO to choose a different PDF?

Best,
Aleksas

You should look at the change introduced for LO:
https://code.launchpad.net/~maddevelopers/mg5amcnlo/2.6.2_heavyion/+merge/342192
and mainly copy-paste those for NLO.
(probably just drop the tracking of the beam since that part will be problematic at NLO)

Note that proton-neutron will not be possible in this case.

Cheers,

Olivier

> On 23 Mar 2020, at 22:27, Skelas <email address hidden> wrote:
>
> Question #689460 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/689460
>
> Status: Answered => Open
>
> Skelas is still having a problem:
> Dear Olivier,
>
> Thanks for the quick reply. I would be happy to have at least symmetric
> beams. Can you point me to what should be done to port heavy ion
> functionality from LO to NLO?
>
> I think the bare minimum what I need are the calculations for proton-
> proton, proton-neutron and neutron-neutron collisions. Maybe it is as
> simple as telling aMC@NLO to choose a different PDF?
>
> Best,
> Aleksas
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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