Confusion on simulation output result
Hi,
I am simulating radiative Bhaba at 1TeV ILC with ISR and beamstrahlung. What I found in different run is different cross-sections varying from ~50pb to ~90pb. Do you think just due to the different seed for random number generation? Below is one such result.
|======
| It Calls Integral[fb] Error[fb] Err[%] Acc Eff[%] Chi2 N[It] |
|======
| [VAMP2] set chain: use chained weights.
1 4690 5.2038349E+04 2.32E+04 44.65 30.58* 0.78
2 4376 3.5869327E+04 2.69E+03 7.50 4.96* 1.33
3 3876 6.1412020E+04 9.01E+03 14.67 9.13 0.75
4 4584 7.5462024E+04 1.29E+04 17.04 11.54 0.75
5 4124 9.3124213E+04 2.74E+04 29.45 18.91 0.48
|------
5 21650 4.0005074E+04 2.50E+03 6.26 9.21 0.48 4.91 5
|------
6 9016 7.4465492E+04 6.62E+03 8.90 8.45* 0.54
7 9016 7.6760487E+04 9.30E+03 12.11 11.50 0.49
8 9016 1.3509076E+05 4.71E+04 34.85 33.09 0.21
|------
8 27048 7.6013984E+04 5.36E+03 7.05 11.60 0.21 0.82 3
|======
What concerned me is with the polarised beam I expected the CS to be on the lesser side it got increased. So, I kept the seed number same to find the CS is actually less.
Now I note the error or error %. Error is 5pb which to me lokked like to be very high. Do you think this is consistent? Even the accuracy (ACC) is 11.6 and Chi^2 is 0.82.
Also, I'm getting a warning saying:
Warning: Encountered events with excess weight: 10302 events ( 10.302 %)
| Maximum excess weight = 1.437E+04
| Average excess weight = 9.287E-01
Again I am sceptic if this is good result or not.
The reason I doubtful is this same kinda problem was there in other packages namely, Calchep. There thwy said this CS is not trustworthy as the error % is high due to the collinear divergence. Even the event generation was taking too indefinite for higher event number. Whizard work like a charm so far. Just this doubt. I suppose Whizard takes care of the hard-collinear divergence by trancating the series at 3rd order. Am I right?
Here is my script-content that I'm using:
#------
model = SM
$integration_method = "vamp2"
process Bhaba = "e-", "e+" => "e-","e+", "A"
sqrts = 1 TeV
beams = e1, E1 => circe2 => isr
!
!beams_pol_density = @(+1), @(-1)
!beams_pol_fraction = 80%, 30%
!
?keep_beams = true
!isr_order = 3
?isr_handler = true
$isr_handler_mode = "recoil"
isr_alpha = 0.0072993
isr_mass = me
!
$circe2_file = "/home/
$circe2_design = "ILC"
?circe2_polarized = false
!
cuts = let subevt @non_isr_photon = [ select if Index > 2 [A] ] in all E > 8 GeV [@non_isr_photon] and all Theta > 5.5 degree [@non_isr_photon] and all Theta < 174.5 degree [@non_isr_photon]
and all Pt < 500 GeV [A]
! and all 174.5 degree > Theta > 5.5 degree [e1:E1]
! and all Dist > 0.4 [e1,E1]
!
analysis = record e_photon (eval E [extract index 1 [sort by - Pt [A]]]) ;
record pt_photon (eval Pt [extract index 1 [sort by - Pt [A]]])
histogram e_photon (0 GeV, 500 GeV, 10 GeV)
histogram pt_photon (0 GeV, 500 GeV, 10 GeV)
!
n_events = 100000
seed = 11683
sample_format = lhef
simulate (Bhaba_Pol)
compile_analysis {$out_file = "Bhaba.dat"}
#------
Regards,
Saumyen
Question information
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- Assignee:
- Juergen Reuter Edit question
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- Juergen Reuter
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