CalcHEP

event generation stuck in a diagram

Asked by Marco Merchand

Dear Experts

I am trying to generate events as lhe file to be used later on CheckMATE. The process of interest is p,p->j, ~X,~X where X is DM.
The batch_file I am using is the following:

"Model: I(1+2)HDMtypeI
Model changed: False
Gauge: Feynman
Process: p,p->j,~X,~X
Alias: p=u,u~,d,d~,s,s~,c,c~,b,b~,g
Alias: j=u,u~,d,d~,s,s~,c,c~,b,b~,g

pdf1: NNPDF23_lo_as_0130_qed(proton)
pdf2: NNPDF23_lo_as_0130_qed(proton)

p1: 6500
p2: 6500

Parameter: MX=50
Parameter: metap=0.0
Parameter: metam=22.930329

parton dits. alpha : ON
alpha(MZ) : 0.118
alpha nf : 5
alpha order : NLO
mb(mb) : 4
Mtop(pole) : 173
alpha Q : T45
Factorization1 Qren
Factorization2 Qren
Showering Qren

#Cuts
Cut parameter : T(~X,~X)
Cut invert: False
Cut min: 100
Cut max:

Number of events (per run step): 1000
Filename: labc_01

#(default) Parallelization mode: local

nSess_1 : 5
nCalls_1: 100000
nSess_2 : 5
nCalls_2: 100000
"
the event generation gets stuck at one diagram for hours. So I have to cancel the generation and i have no event files at the end of the day.

Since I want to make a grid in parameter space, then use CheckMATE at each point, I tried different parameter values and it runs fast, producing the event files in a reasonable amount of time except for this specific set of values. I checked there isn't any sort of singularity in this process. The Higgs and a heavy Higgs are the only possible mediators.

Can I send you my .mdl files so you could help me out?

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Launchpad Janitor (janitor) said : 		#1

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

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Alexander Belyaev (alexander.belyaev) said : 		#2

Dear Marco,
apologies we have missed your request you asked long ago.
I am happy to take a look now. If you could send me your model, I will be able to advice on hwo to deal with you process.
Regards,
Alexander

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Launchpad Janitor (janitor) said : 		#3

This question was expired because it remained in the 'Needs information' state without activity for the last 15 days.

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Alexander Belyaev (alexander.belyaev) said : 		#4

I was going through the expired question and found yours which was missed.
Apologies!

You did not set the cut on the PT of the jet,
so your proces sis divergent, so the corss section is not converges, the error on it is large.
This means that you can not really trust the cross section you are getting.
Moreover, if the accuracy is bad, then efficiency of the event generation is very low and
the process of event generation could take forever. This what you have.

If you set the cut on the PT of the jet,
you will be able to generate events

regards,
Alexander

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