email from Patricia
Dear Clement
hope this find you well.
As you know I am preparing some studies for different masses of ALP signal, photon photon → ALP → photon photon, from 0.1 GeV to 300 GeV. My LHEs have 25K events for each mass point with very loose cuts (ptmin=0.01GeV, |eta|=3)
After passing my LHEs using the
DelphesPythia8 $DELPHES_DIR/cards/delphes_card_IDEAtrkCov.tcl card, I see different efficiencies in the output samples.
For instance, for sqrt(s)= 91GeV:
for ALP = 0.1 GeV, #eventsDelphes = 23205
for ALP = 0.5 GeV, #eventsDelphes = 9296
for ALP = 1 GeV, #eventsDelphes = 14910
for ALP = 10 GeV, #eventsDelphes = 49889
for ALP = 50 GeV, #eventsDelphes = 50639
I would like to understand this behavior. May I kindly ask you how the detector is designed for photon identification? In particular, is the fragment below, from
delphes_card_IDEAtrkCov.tcl , the only one setting the efficiency of photons?
set EfficiencyFormula
{
(energy
< 2.0)
* (0.000)+
(energy
>= 2.0) * (abs(eta) <= 0.88)
* (0.99)
+
(energy
>= 2.0) * (abs(eta) >0.88 && abs(eta) <= 3.0) * (0.99) +
(abs(eta)
> 3.0)
* (0.000)
}
Thank you.
Regards Pat
Dear @prebello , @dde,
moving this to the forum.
the efficiencies are the raw events you get out of delphes, or its there some cuts from your 25k events?
I don’t really get how you can get more events than the 25k generated ones
Clement
Hi,
I have meant “#eventsDelphes” as the entries in the output Delphes distributions, as Photon.PT, Photon.E etc
I prepared MC samples in Superchicv4 that suggests adding the lines below for Pythia
! for SC4
PartonLevel:ISR = off
PartonLevel:MPI = off
PartonLevel:Remnants = off
Check:event = off
LesHouches:matchInOut = off
Apart from it, I have used the beam spread from FCC instructions
Beams:allowMomentumSpread = on
Beams:sigmaPzA = 0.06006
Beams:sigmaPzB = 0.06006
Then in FCC Delphes environment, I have processed
DelphesPythia8 $DELPHES_DIR/cards/delphes_card_IDEAtrkCov.tcl Pythia_LHE.cmd DelphesPy8.root
From my point of view, Pythia is producing more photons while showering the parton level and Delphes detector is selecting them accordingly. Does it make sense?
Cheers Pat
Hello @prebello ,
the efficiency formulae is as you found in the configuration.
For what concerns the Beam Energy Spread together with LHE, this is not something we should be using in pythia, see the authors note here:
http://home.thep.lu.se/~torbjorn/pythia82html/BeamParameters.html#section2
could you possibly rerun DelphesPythia8 (plain delphes events BTW, and not yet EDM4Hep) removing the BES?
Clement
Hi @clement.helsens
Thank you for this new information.
I have followed the instructions in the page below.
https://github.com/HEP-FCC/FCCeePhysicsPerformance/blob/master/General/README.md#generating-events-under-realistic-fcc-ee-environment-conditions
https://github.com/HEP-FCC/FCCeePhysicsPerformance/blob/master/General/README.md#beam-energy-spread
“It is important to take into account the beam energy spread when generating events. Some Monte-Carlo programs (e.g. Pythia, Whizard) offer a built-in possibility to convolute the matrix elements with a Gaussian beam energy distribution.”
Maybe you want to update it.
Cheers Pat
Hi @clement.helsens
I have noticed a weird behavior with light-by-light at M_X = 0.5 GeV and 1 GeV, so far at 91GeV FCC-ee scenario (I didn’t test others), after detector simulation: the inv mass returns negative values after detector simulation.
The parton level values are ok though.
Would you foresee any detector parameter that could affect this low mass region? For M_X=0.1 GeV, it works well.
Thank you
Cheers Pat
Hello @prebello ,
I must admit I have no idea on top of my head. Some debugging is needed.
Are you sure that the invariant mass you reconstruct is selecting signal photons? do you apply some truth matching?
If not I would start by understanding how the reconstructed photon differs from the parton level one
cheers,
Clement