Madgraph and events involving mesons

Asked by Maksym Ovchynnikov on 2018-03-27

Hi!

I'm a newbie in madgraph and can't find the answer on simple question.

Consider p p collisions. I need to compute the number of B^+ mesons produced in these collisions. However, I don't know whether this is possible. Could you please answer?

If this is impossible, then how Madgraph calculates number of events in p p collisions when neutrinos are produced? Namely, most of neutrinos are produced in decays of mesons, and if Madgraph doesn't work with mesons, then it can't predict correct amount of neutrinos.

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2018-03-28
Last query:
2018-03-28
Last reply:
2018-03-27
Maksym Ovchynnikov (name-xxx) said : #1

Another related question. Am I right that when simulating events, say, p p > b b~ > ve with pre-installed Pythia the output will automatically include production from hadronized states?

Dear Maksym,

MadGraph is handling the hard process of the collisions.
The parton-shower and the hadronization are not include in our soft
but you can use our software to run those codes (for example Herwig of Pythia).

> If this is impossible, then how Madgraph calculates number of events in p p collisions when neutrinos are produced? Namely, most of neutrinos are produced in decays of mesons, and if Madgraph doesn't work with mesons, then it can't predict correct amount of neutrinos.

At the output of MG5aMC, you will only have the neutrinos from the hard process.
The production and decay of the mesons are handle by the code you choose and simulate according to their setup.

> Another related question. Am I right that when simulating events, say, p
> p > b b~ > ve with pre-installed Pythia the output will automatically
> include production from hadronized states?

We do not have pre-installed Pythia. (we just have a command to download his source from the web and run their installer)
But if you have an version of pythia8 available, then the default (at LO) is to use it.

Cheers,

Olivier

> On 27 Mar 2018, at 18:22, Maksym Ovchynnikov <email address hidden> wrote:
>
> New question #667277 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/667277
>
> Hi!
>
> I'm a newbie in madgraph and can't find the answer on simple question.
>
> Consider p p collisions. I need to compute the number of B^+ mesons produced in these collisions. However, I don't know whether this is possible. Could you please answer?
>
> If this is impossible, then how Madgraph calculates number of events in p p collisions when neutrinos are produced? Namely, most of neutrinos are produced in decays of mesons, and if Madgraph doesn't work with mesons, then it can't predict correct amount of neutrinos.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Maksym Ovchynnikov (name-xxx) said : #3

Thanks Olivier Mattelaer, that solved my question.

Maksym Ovchynnikov (name-xxx) said : #4

Could you please clarify to me the following?

Just to be sure: first I use madgraph to generate .lhe files, and then somehow run them in within pythia with specifying final channel (say, from b b~ output .lhe file obtain first B-mesons, and then their decay onto some particle)? Did I understand you correctly that this stage is completely independent on madgraph?

Hi,

> Did I understand you correctly that this stage is
> completely independent on madgraph?

yes. This rely on factorization theorem obviously.

Cheers,

Olivier

> On 28 Mar 2018, at 02:32, Maksym Ovchynnikov <email address hidden> wrote:
>
> Question #667277 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/667277
>
> Maksym Ovchynnikov posted a new comment:
> Could you please clarify to me the following?
>
> Just to be sure: first I use madgraph to generate .lhe files, and then
> somehow run them in within pythia with specifying final channel (say,
> from b b~ output .lhe file obtain first B-mesons, and then their decay
> onto some particle)? Did I understand you correctly that this stage is
> completely independent on madgraph?
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Maksym Ovchynnikov (name-xxx) said : #6

Dear Olivier, thank you! Sorry for this qiestion, but maybe you know where to find examples of code on pythia allowing to compute first hadronization to given meson and then to decay from give .lhe file? I tried to find suxh program in pythia examples, but it seems that there are no such examples.