maddump

Details about meson Flux simulation

Asked by Guillermo Palacio

Hi MadDump team,

 I am using MadDump to study of a Dark photon model and explore the potential sensitivitiy reach of DUNE experiment. However, I am facing some issues and have some questions regarding the use of maddump.My questions are:

1. In the SHiP example folder found inside the maddump plugin you provide a hepmc2 file with the information of pions, etas and additional mesons. Did you use Pythia for the generation of these events?.

If you use Pythia, would you please tell me if you considered HardQCD or SoftQCD processes or a combination of both?.

Any parton distribution PDF was used for the generation? or preliminary cut on some kinematic variable at the generation level?

2. In the particular case of DUNE Near Detector, one of the backgrounds for my signal is the muon neutrino - electron scattering. I asked in the launchpad sometime ago about the possibility of that background simulation in maddump. I did perform the simulation by using pythia ( with the flag of SoftQCD processes only and simulating the collision of proton at 120 GeV against carbon at rest) and storing only charged pion and later implementing an effective coupling that allows the charged pion to decay into muon neutrino and muon. However, the number of events according to the Maddump output is around twice the number of events of background events reported in the literature. However, this number depends on the choice of SoftQCD vs HardQCD in pythia and for that I am writing.

Any comment, answer or suggestion will be of great help.

Cheers,

Guillermo Palacio

Question information

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Assignee:
Luca Edit question
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Luca
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Luca (lbuono) said : 		#1

Dear Guillermo,

1. the neutral mesons were produced with Pythia using the SoftQCD generation.
We did not put any cuts at the generation level and we stayed with the default
settings.
According to Pythia manual, one should not use simultaneously the SoftQCD and
the hardQCD generation because of double counting.

2. can you briefly recall me why you are not generating the neutrino flux directly
in Pythia ? Is this due to the focus horn system in DUNE?
According to my understanding, you should stay with the SoftQCD simulation
if you want to generate the minimum bias.

Cheers,
Luca

Revision history for this message
Guillermo Palacio (gapalacic) said : 		#2

Dear Luca,

Thanks a lot for the anwers.

1. For the meson flux I am using pythia and considering only the SoftQCD generation. I asked about HardQCD because I was thinking that maybe you used any special parton distribution function and a cut on p_T at the generation level.

2. Regarding the fluxes. I did generate directly the neutrino fluxes in pythia, but I was unable to added to the other chain of processes shown in the maddump examples, so instead I do generate the charged pion fluxes and then decay those to muon-neutrino plus muon by using an effective interaction (in an analogous way as is done for the neutral mesons shown in the example)

Now, regarding the DUNE setup, after the colission of the proton against the fixed-target there are some focusing magnetic horns, the charged pions travel inside it before decay. It is correct to assume that for that reason alone the background can not be simulated using maddump?

Cheers

Revision history for this message
Best Luca (lbuono) said : 		#3

Dear Guillermo,

thanks for the clarification about the second point, you are right. In principle it is possible to
use directly the neutrinos provided by Pythia by selecting neutrino as DM particle. I do not know
if it will work out of the box in the public version of maddump (in the development version
I'm currently trying to work also in that direction)

As for the magnetic horns, I cannot predict the impact of totally neglecting their effects.
They are responsible for a modification of the neutrino flux reaching the detector.
Have you tried to contact people in DUNE for this? Perhaps, they have public data
of they simulation for the neutrino fluxes.

Cheers,
Luca

Revision history for this message
Guillermo Palacio (gapalacic) said : 		#4

Thanks Luca, that solved my question.

Revision history for this message
Guillermo Palacio (gapalacic) said : 		#5

Dear Luca,

Thanks a lot for the help.

The neutrino fluxes at DUNE near detector are free access (https://home.fnal.gov/~ljf26/DUNEFluxes/). I will use it to compute the total number of events for the background and also to see the background distribution. Later on I will check this results with maddump output.

Cheers,

Guillermo Palacio