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Opened 11 years ago

Closed 11 years ago

Last modified 11 years ago

#221 closed How to (fixed)

missing electrons in 4 electrons finale state signal

Reported by: emran ali Owned by:
Priority: major Milestone:
Component: Delphes code Version: Delphes 3
Keywords: Cc:

Description

hi delphes team
i used calchep to produce 4 electrons finale stat signal "2 e- and 2e+" , i linked it with pythia stand alone .. when i run delphes ,i found that, only 2 electrons found in delphes tree !!!!!!!!!!
Also i tried to run the .lhe file from calchep directly to delphes " with out pythia "
i gives me the same result .
Best
emran

Attachments (3)

hepmc4eout.dat (2.2 MB ) - added by emran ali 11 years ago.
hepmc4eout_event_0.png (13.1 KB ) - added by Pavel Demin 11 years ago.
hepmc2e.dat (2.3 MB ) - added by emran ali 11 years ago.

Change History (13)

comment:1 by Pavel Demin, 11 years ago

Dear Emran,

Is it possible, that some of the electrons have transverse momenta less than 10 GeV? By default, Delphes rejects electrons with pT < 10 GeV.

It would be also very helpful if you could provide a small (~10 events) sub-sample of your events.

Regards,

Pavel

by emran ali, 11 years ago

Attachment: hepmc4eout.dat added

comment:2 by emran ali, 11 years ago

hi Pavel
i have attached the hepmc file but is there any way to fix this ????
Best
emran

by Pavel Demin, 11 years ago

Attachment: hepmc4eout_event_0.png added

comment:3 by Pavel Demin, 11 years ago

Hi Emran,

Thanks for the hepmc file.

Looks like the electrons are rejected by the isolation criteria.

I've looked at some of the events using event display and found that there are always 2 electrons/positrons that are very close to each other.

Here are the electrons/positrons from the first event:

P 607 11 -1.5058580625894925e+04 6.9246571676718202e+04 -6.1031001918057031e+04 9.3523428801775110e+04 5.1099999999999990e-01 1 0 0 0 0

P 609 11 3.1333631066264282e+05 -9.4029348818282233e+04 -1.1425374063108706e+04 3.2734034458232252e+05 5.1099999999999990e-01 1 0 0 0 0

P 610 -11 -2.9696830790558219e+04 1.2253455884022835e+04 -3.3211970467438905e+03 3.2296738073506680e+04 5.1099999999999990e-01 1 0 0 0 0

P 612 -11 9.9769099634468905e+04 -5.0120315795352661e+04 1.6751886865299657e+04 1.1290059792169066e+05 5.1099999999999990e-01 23 0 0 -465 0

and here is an event display for this event with electrons/positrons tracks in red:

Version 0, edited 11 years ago by Pavel Demin (next)

comment:4 by Michele Selvaggi, 11 years ago

Hi Emran,

you could try to relax the isolation criteria in your card, and see how the average number of electrons increases.
For instance, you could increase the value of the parameter PTRatioMax for the electron isolation:

module Isolation ElectronIsolation {
...
set PTRatioMax 0.5

If you set PTRatioMax to a very high value (say 1000), all your electrons should pass.

I would however suggest you go and check how CMS/ATLAS perform this type of analysis with very boosted collimated electrons and which kind of isolation criteria they use.

Cheers,

Michele

comment:5 by emran ali, 11 years ago

Hi dr Michele
i set PTRatioMax = 1000 , but still three electrons finale state could pass.
what if i reduce th deltaR to be say 0.1 ????
Cheers
emran

comment:6 by Michele Selvaggi, 11 years ago

Hi Emran,

setting deltaR->0 or PTRatioMax->inf should give you the same result. It is possible you lose some of your electrons because of finite detector acceptance/efficiency.
What do you believe this is a problem? You will always have some events with less than four electrons.

Michele

comment:7 by emran ali, 11 years ago

Thanks Dr Michele & Dr Pavel
i did what you mentioned above but still not all electrons pass . Also i made DY process from SM
,it gives the same error , while the outgoing 2 electrons shouldnt be collimated or close together.
i attached file with DY process with 10 events " there is only 13 electrons in electron branch" !!!
thanks alot for your interset
Emran

by emran ali, 11 years ago

Attachment: hepmc2e.dat added

comment:8 by Michele Selvaggi, 11 years ago

Hi Emran,

by "all your electrons should pass", I meant, "all electrons that pass the other selection criteria (geometrical acceptance, efficiency ..) should pass". It is perfectly normal that some electrons do not pass these criteria.

Michele

comment:9 by Pavel Demin, 11 years ago

Resolution: fixed
Status: newclosed

comment:10 by ahmed hammad, 11 years ago

Hi Dr Michele
iam srry for my leak information , iam just a new user.
i understood what you mentioned above , and , ican calculate the acceptance of the detector by comparing eta of the gen level to that from delphes .
by means of 4 electrons + missing ET , it was the decay of Zp .
i tried Zp->2e , it works good and the plot of Zp mass achieved at exactly at MZp=1500. but , i wonder when i try to examine Zp->4e+missing Et , it gives me wrong results .
i tried to reconstruct MZp as M=sqrt(2*energy(4e)*energy(missing ET)*(1-cos(phi"4e"-phi"Et"))).
Finally i want to thank you for your help .
Emran

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