comparison of acceptances and radiative effects for w/z for pythia, herwig and mc@nlo
DESCRIPTION
Comparison of acceptances and radiative effects for W/Z for Pythia, Herwig and Mc@nlo. Marc Goulette, Daniel Froidevaux ATLAS CAT Physics Meeting, CERN 18 April 2007. Outline. Introduction Selection cuts Electron acceptances Understanding the differences Conclusion and plans. - PowerPoint PPT PresentationTRANSCRIPT
Comparison of acceptances and radiative effects for W/Z for Pythia, Herwig and Mc@nlo
Marc Goulette, Daniel Froidevaux
ATLAS CAT Physics Meeting, CERN18 April 2007
2/3118 April 2007 Marc Goulette
Outline
1. Introduction
2. Selection cuts
3. Electron acceptances
4. Understanding the differences
5. Conclusion and plans
3/3118 April 2007 Marc Goulette
Study on We and Zee events at the generator level
Here the study is concentrated on We Software
Release 11.0.4 CBNT_Truth-00-00-41 UserAnalysis-00-05-11 standard DC3-jobOptions (including Photos)
Monte Carlo Generators Pythia 6.323 Lowest order qq’ W Born Herwig 6.507 Jimmy 4.0 Lowest order (approx.) qq’ W Born MC@NLO 3.2 Next to Leading Order At least ~100 K events produced for each generator
1. Introduction
4/3118 April 2007 Marc Goulette
Main Parameters
PYTHIA HERWIG MCATNLO
mW (GeV) 80.42 80.425 80.42
W (GeV) 2.120 2.124 2.124
mZ (GeV) 91.1876 91.19 91.19
Z (GeV) 2.4952 2.495 2.495
σW (pb) 17 210 ± 132 17 315 ± 132 19 885 ± 138
σW+(pb) 10 011 ± 100 10 088 ± 100 11 456 ± 110
σW-(pb) 7 199 ± 85 7 224 ± 85 8 429 ± 82
Same Mass and same Width for all Herwig and Pythia cross sections in agreement to better than 1% !! Higher McAtNlo cross section as expected (see spare slides for K-factors)
5/3118 April 2007 Marc Goulette
Parton Density Function (PDFs) description
PYTHIA: LHAPDF version 4.0 CTEQ6L1-LO with LO alpha_s
HERWIG: HWLHAPDF modpdf 10042 LHAPDF version 4.0 CTEQ6L1-LO with LO alpha_s
MCATNLO: HWLHAPDF modpdf 10000 LHAPDF version 4.0 CTEQ6m (NLO version of CTEQ6L1-LO)
6/3118 April 2007 Marc Goulette
2. Selection cuts
LEPTON FILTER: pT_cut = 0.0 _cut = 5.0
STANDARD CUTS: pT
e > 25 GeV pT
> 25 GeV || < 2.5 Electron and photon merged if R = (2+2) < 0.04
7/3118 April 2007 Marc Goulette
Electron acceptances as a function of max with pTe > 25 GeV,
pT > 25 GeV and || < 2.5:
3. Electron acceptances for We
Cut 1.0 2.5
MCATNLO W 16.14 0.16 38.97 0.21
MCATNLO W+ 15.01 0.11 38.50 0.15
MCATNLO W- 17.27 0.12 39.45 0.15
HERWIG W 15.22 0.11 36.65 0.15
HERWIG W+ 14.11 0.14 36.15 0.19
HERWIG W- 16.78 0.18 37.34 0.23
PYTHIA W 14.46 0.11 35.77 0.14
PYTHIA W+ 13.43 0.13 35.47 0.19
PYTHIA W- 15.90 0.17 36.19 0.22
HERWIG/MCATNLO W 94.34 1.16 94.04 0.64
PYTHIA/MCATNLO W 89.61 1.11 91.79 0.62
HERWIG/PYTHIA W 105.30 1.09 102.50 0.59
HERWIG W+ / MC W+ 94.02 1.17 93.90 0.62
PYT W+ / MC W+ 89.46 1.11 92.12 0.61
HERWIG W+ / MC W- 97.17 1.22 94.67 0.69
PYT W- / MC W- 92.07 1.17 91.76 0.67
Acceptances in %
Acc
epta
nce
_cut
Acc
epta
nce
rati
o
_cut Important differences (413%) !!
8/3118 April 2007 Marc Goulette
4. Source(s) of the difference ?
PDFs (exactly the same used, at least for Pythia/Herwig) ISR/FSR/Underlying Event pTw Atlas interfaces to the generators Photos interfaces to different generators Other parameters (mw and w identical, s, QCD, …)
9/3118 April 2007 Marc Goulette
W+ / W- rapidity (100 K events)
yw+
W-
Nu
mbe
r of
eve
nts
yw-
Nu
mbe
r of
eve
nts
Shape difference due to p-p collision (more valence u than valence d) Same fluctuations observed for both charged bosons W+ chosen as an example in the analysis
u.d u.d
W+
_ _
10/3118 April 2007 Marc Goulette
Rapidity and pseudorapidityN
um
ber
of e
ven
ts
Nu
mbe
r of
eve
nts
Rat
io
Rat
io
W yW
yW yW
After cutsNo cuts Importantfluctuationsfor both (next slide..)
11/3118 April 2007 Marc Goulette
Pdfs for Pythia, Herwig and Mcatnlo
Pythia isquitedifferent for all cases.
xi = fraction of energy taken by the quark
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
xu xd
xc xs
_
_
Herwig and mcatnlo are close for some quarks (xc and xd).
_
Why are pdfsdifferent despitechoice of sameset inJobOptions ?
12/3118 April 2007 Marc Goulette
Do we get mW from √(x1.x2.s) for e.g. udW ?N
um
ber
of e
ven
tsN
um
ber
of e
ven
ts
Nu
mbe
r of
eve
nts
~mW (GeV)
~mW (GeV)~mW (GeV)
Important asymmetry for Pythia (
see next slides)
MC@NLO HERWIG
PYTHIA
_
13/3118 April 2007 Marc Goulette
pTe>25 GeV, pT
>25 GeV and ||<2.5:
Big effect !!
Cut 1.0 2.5
MCATNLO W 16.10 0.16 39.56 0.21
MCATNLO W+ 14.72 0.11 38.73 0.15
MCATNLO W- 17.48 0.12 40.38 0.15
HERWIG W 14.52 0.11 36.80 0.15
HERWIG W+ 13.71 0.14 36.18 0.20
HERWIG W- 15.60 0.17 37.63 0.23
PYTHIA W 14.87 0.11 37.31 0.15
PYTHIA W+ 14.07 0.14 36.80 0.19
PYTHIA W- 16.00 0.17 38.03 0.23
HERWIG/MCATNLO W 90.18 1.12 93.03 0.63
PYTHIA/MCATNLO W 92.35 1.13 94.32 0.63
HERWIG/PYTHIA W 97.65 1.01 98.63 0.55
HERWIG W+ / MC W+ 93.13 1.18 93.42 0.62
PYT W+ / MC W+ 95.58 1.17 95.02 0.61
HERWIG W- / MC W- 89.28 1.15 93.18 0.67
PYT W- / MC W- 91.55 1.16 94.17 0.67
Acceptances in %
Acc
epta
nce
rati
o
before
Remove Underlying Event
_cut
Acc
epta
nce
rati
o
after
_cut
14/3118 April 2007 Marc Goulette
No Underlying Event: effect on pdfs
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
xd
xs
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
xu
xc
_
_
Pythia isstill quitedifferent for all (xc is best).
Herwig and mcatnlo almost equal for all quarks (except xu).
15/3118 April 2007 Marc Goulette
pTe>25 GeV, pT
>25 GeV and ||<2.5:
global increase of acceptanceand big effect on ratios !!
Cut 1.0 2.5
MCATNLO W 17.63 0.17 43.22 0.22
MCATNLO W+ 16.45 0.11 42.73 0.15
MCATNLO W- 18.80 0.12 43.71 0.15
HERWIG W 16.68 0.11 40.58 0.15
HERWIG W+ 15.42 0.15 39.65 0.20
HERWIG W- 18.44 0.19 41.88 0.24
PYTHIA W 16.81 0.11 41.88 0.15
PYTHIA W+ 16.27 0.15 41.50 0.19
PYTHIA W- 17.58 0.18 42.40 0.23
HERWIG/MCATNLO W 94.63 1.11 93.89 0.59
PYTHIA/MCATNLO W 95.40 1.10 96.89 0.59
HERWIG/PYTHIA W 99.20 0.95 96.90 0.50
HERWIG W+ / MC W+ 93.75 1.10 92.79 0.57
PYT W+ / MC W+ 98.93 1.12 97.13 0.57
HERWIG W- / MC W- 98.09 1.12 95.82 0.64
PYT W- / MC W- 93.47 1.11 97.00 0.63
Acceptances in %
Acc
epta
nce
rati
o
before
No UE and no Initial State Radiation
_cut
Acc
epta
nce
rati
o
after
_cut
16/3118 April 2007 Marc Goulette
No UE and no ISR: effect on pdfs
Pdfs
Better
Nu
mbe
r of
eve
nts
xd
xsNu
mbe
r of
eve
nts
xc
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
xu_
_
17/3118 April 2007 Marc Goulette
No UE and no ISR: Pythia 6.3 vs Pythia 6.4N
um
ber
of e
ven
ts
xd
xsNu
mbe
r of
eve
nts
xc
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
xu_
_
Almost no changes (even on the acceptances)
18/3118 April 2007 Marc Goulette
pTe>25 GeV, pT
>25 GeV and ||<2.5:
Some improvement but still not satisfactory.
Cut 1.0 2.5
MCATNLO W 17.63 0.17 43.22 0.22
MCATNLO W+ 16.45 0.11 42.73 0.15
MCATNLO W- 18.80 0.12 43.71 0.15
HERWIG W 17.34 0.05 42.80 0.07
HERWIG W+ 16.26 0.07 41.63 0.09
HERWIG W- 18.86 0.08 44.44 0.11
PYTHIA W 16.56 0.05 41.73 0.07
PYTHIA W+ 15.77 0.07 41.49 0.09
PYTHIA W- 17.68 0.08 42.08 0.11
HERWIG/MCATNLO W 98.38 0.98 99.03 0.52
PYTHIA/MCATNLO W 93.93 0.93 96.55 0.51
HERWIG/PYTHIA W 104.70 0.46 102.60 0.24
HERWIG W+ / MC W+ 98.86 0.80 97.43 0.41
PYT W+ / MC W+ 95.87 0.78 97.09 0.41
HERWIG W- / MC W- 100.30 0.79 101.70 0.43
PYT W- / MC W- 94.00 0.75 96.27 0.42
Acceptances in %
Acc
epta
nce
rati
o
before
No UE, no ISR and no Matrix Element Correction
Acc
epta
nce
rati
o
after
_cut
_cut
19/3118 April 2007 Marc Goulette
No UE, no ISR, no ME: back on yW+
yw+
W+
Nu
mbe
r of
eve
nts
Error bars are correct ! Pythia and Herwig normalized to Mcatnlo Fluctuations still important and cannot be attributed to statistics
Standard100 K events for all
generators
W+
Nu
mbe
r of
eve
nts
yw-
no UE, no ISR, no ME100 K Mcatnlo
500 K Pythia & Herwig
20/3118 April 2007 Marc Goulette
No UE, no ISR and no ME: effect on pdfs
Some improvement
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
xc
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
xu xd
xs
_
_
21/3118 April 2007 Marc Goulette
√(x1.x2.s) for all generators
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
~mW (GeV)
~mW (GeV)~mW (GeV)
The tail is still there andneeds to be understood
MC@NLO HERWIG
PYTHIA
22/3118 April 2007 Marc Goulette
Problem in Pythia to ATLAS interface?
What happened here ?
- We should have : Py_s~+Py_c = Py_W and the same for Px and Pz …- Could it be due to a different frame between the original quarks and the W ?
23/3118 April 2007 Marc Goulette
Problem in Pythia to ATLAS interface?
Standard configuration, 5 K events produced
(GeV)
(MeV) (MeV)
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
But here this isclearly important ..
24/3118 April 2007 Marc Goulette
Problem in Pythia to ATLAS interface?No UE, no ISR, no ME, 5 K events produced
(MeV)
(MeV) (MeV)
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
And stays after UE, ISR and ME removal (but effectSmall, could be precision of
interface ?)
-Torbjorn S. checked on 10 K events (Thanks !): nice delta func. in standalone mode !!
25/3118 April 2007 Marc Goulette
Problem in Herwig to ATLAS interface?
(MeV)
(MeV) (MeV)
No UE, no ISR, no ME, 3 K events produced
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Similar effectseen in Herwig
26/3118 April 2007 Marc Goulette
- Events without a W in theprintout are all without Photons !- These events are in fact“W without jets” (76.3 % of all events).
- Events with a W in the recordAre in fact “W+Jets” (23.7 %).- For these events, we can seesome photons coming out (asexpected..).
McAtNlo printout
27/3118 April 2007 Marc Goulette
Thus, the total number of photons generated with MC@NLO compared to Pythia and Herwig is much lower:
Number of photons generated
- Problem still present in 12.0.X. Thus for other (later) studies, the evgen files and the samples will need to be redone (but Borut K. and Jon B. are aware of that…)- Impact of Photos on acceptance is small (see spare slides).
Nb of Events generated
Nb of Photons
(pT > 0.15 keV)
Nb of Photons (pT
> 10 GeV)
Mcatnlo W+ 105 000 19 236 1008 (1.0%)
Mcatnlo W- 105 000 19 278 882 (0.8%)
Herwig 105 000 80 703 3381 (3.2%)
Pythia 105 000 83 045 3990 (3.8%)
28/3118 April 2007 Marc Goulette
Applying a pTw weighting factor
Weighting factor
Weighting factor
Nb
of e
vent
sN
b of
eve
nts
pTw Mcatnlo
pTw Herwig
pTw (MeV/c)
pTe (MeV/c)
pTe Herwig
before
pTe Herwig
after
Low statistics
29/3118 April 2007 Marc Goulette
pTw: effect on electron acceptances
pTe>25 GeV, pT
>25 GeV and ||<2.5:
Almost no effect because pdfs obscure everything at the moment
Acceptances in %
Acc
epta
nce
rati
o
_cut
before
Cut 1.0 2.5
MCATNLO W 16.14 0.16 38.97 0.21
MCATNLO W+ 15.01 0.11 38.50 0.15
MCATNLO W- 17.27 0.12 39.45 0.15
HERWIG W 15.14 0.11 36.40 0.15
HERWIG W+ 14.01 0.14 35.91 0.19
HERWIG W- 16.67 0.18 37.06 0.23
PYTHIA W 14.44 0.11 35.73 0.14
PYTHIA W+ 13.41 0.13 35.36 0.19
PYTHIA W- 15.80 0.17 36.03 0.22
HERWIG/MCATNLO W 93.83 1.16 93.41 0.64
PYTHIA/MCATNLO W 89.48 1.11 91.68 0.62
HERWIG/PYTHIA W 104.85 1.09 101.88 0.59
HERWIG W+ / MC W+ 93.33 1.16 93.29 0.62
PYT W+ / MC W+ 89.38 1.11 91.84 0.61
HERWIG W+ / MC W- 96.55 1.22 93.95 0.69
PYT W- / MC W- 91.49 1.16 91.34 0.67
Acc
epta
nce
rati
o
after
_cut
30/3118 April 2007 Marc Goulette
Source(s) of the difference ? Status
Done Pdfs partly understood with UE, ISR and ME
But after no ME, no ISR, no UE, all generators are not identical !!
pTw YES, but obscured by pdfs Photos interfaces to different generators NO Pythia shower test with Pythia 6.4 NO
To do Pdfs: Atlas interfaces to generators explain mW tail, pdfs and acc.? ( try Mcatnlo with CTEQ 6L for complete consistency check) Other parameters (s, QCD, …) ? Running Herwig and Pythia in standalone mode ?
31/3118 April 2007 Marc Goulette
Conclusions W enu : Important differences found on the acceptance QED radiation not correct for mcatnlo evgen samples Differences now attributed to pdfs but not fully understood yet There may be some problem in the generator to Atlas interface ?
Plans Continue study : interfaces ?, Other param., run in standalone mode ? Revisit pT
W impact on acceptance Quantify effects for Z e e Study in detail Photos effect Derive estimate of systematic uncertainty on acceptance using
TruthAtlfastFullSim
Conclusion and plans
32/3118 April 2007 Marc Goulette
Additional material
33/3118 April 2007 Marc Goulette
Acceptances for ZeeElectron acceptances as a function of _max with pTe1 > 25 GeV,
pTe2 > 25 GeV and || < 2.5:
cut 0.5 1.0 1.5 2.0 2.5
mcatnlo 11.28 22.47 33.29 42.90 52.59
herwig 10.74 20.97 30.86 40.62 50.14
pythia 10.61 20.91 31.84 41.96 51.52
Mc / Her 105.0 107.2 107.9 105.6 104.9
Mc / Pyt 106.3 107.5 104.6 102.2 102.1
Her / Pyt 101.2 100.3 96.9 96.8 97.3
Difference between Herwig and Pythia is smaller (less than 3.2 %), whichbetter shows that the same pdfs have been used…
34/3118 April 2007 Marc Goulette
Main Parameters
PYTHIA HERWIG MCATNLO
mW (GeV) 80.42 80.425 80.42
W (GeV) 2.120 2.124 2.124
mZ (GeV) 91.1876 91.19 91.19
Z (GeV) 2.4952 2.495 2.495
PDG 2006
80.403 0.029
2.141 0.041
91.1876 0.0021
2.4952 0.0023
Tevatron (2006): mW = 80.413 ± 0.48 GeV
35/3118 April 2007 Marc Goulette
Here we have analytic calculations both at LO and at NLO (NLO code courtesy of James Stirling). For any PDF we get the following total cross-section to be compared with those from the generators. W- cross-section (pb) CTEQ6L1 with LO alphas CTEQ6L1 with NLO alphas CTEQ61m NLO LO calculation 7379.5 6890.1
7570.0 NLO calculation 8172.8 7552.0 8562.8 W+Cross-section (pb) CTEQ6L1 with LO alphas CTEQ6L1 with NLO alphas CTEQ61m NLO LO calculation 10159.3 9472.2
10107.1 NLO calculation 11373.4 10530.1
11512.1 SO 1) the fully correct Nlo calculations are in agreement between the analytic code and MC@NLO to 1% 2) the fully LO calculation is within 1% for W+, a little worse for W- 3) using LO PDf with LO alphas is closer to the truth than using LO PDF with NLO alphas but NLO is still
needed 4) the k-factors for both types of LO PDF are very similar 5) if we want a k-factor which can take us from LO calculation with Lo PDF straight to NLO calculation
with Nlo PDF then we now have it in the above table by dividing bottom right numbers by top left numbers. Then it explains the numbers fine.
Pythia CTEQ6L1-L0 with LO alphas Herwig CTEQ6L1-L0 with LO alphas Mcatnlo CTEQ6m W+ cross-section (pb) 10011 10088 11456
W- cross-section (pb) 7199 7224 8429
Thanks a lot to Amanda Cooper Sarkar !!
K factors
36/3118 April 2007 Marc Goulette
Some numbers
Fraction W+ / W-: Fraction of W- for Herwig: 43806 (41.72 %) Fraction of W+ for Herwig: 61173 (58.26%) Fraction of W- for Pythia: 46013 (41.83%) Fraction of W+ for Pythia: 63987 (58.17%)
Nb of electrons / neutrinos after LeptonFilter cuts: Mcatnlo W-: 105 000 / 104 916 Mcatnlo W+: 105 000 / 105 000 Herwig: 104 979 / 104 979 Pythia: 110 000 / 110 000
Number of events W+jets: Mcatnlo W+: 24 864 (23.68%) Mcatnlo W-: 24 990 (23.80%)
Number of events with weights -1: Mcatnlo W+: 9 324 (8.88%) Mcatnlo W-: 9 051 (8.62%)
Number of events generated: MC@NLO W- with Photos: 105 000 MC@NLO W- without Photos: 105 000 MC@NLO W+ with Photos: 105 000 MC@NLO W+ without Photos: 105 000 HERWIG W with Photos: 105 000 HERWIG W without Photos: 105 000 PYTHIA W with Photos: 110 000 PYTHIA W without Photos: 110 000
Number of Photons generated: MC@NLO W- with Photos: 19 236 MC@NLO W- without Photos: 357 MC@NLO W+ with Photos: 19 278 MC@NLO W+ without Photos: 441 HERWIG W with Photos: 80 703 HERWIG W without Photos: 558 PYTHIA W with Photos: 86 999 PYTHIA W without Photos: 46 783
37/3118 April 2007 Marc Goulette
Info on JobOptions and samples
Pythia and Herwig samples :
- http://alxr.usatlas.bnl.gov/lxr/source/atlas/Generators/DC3_joboptions/share/- In particular DC3.005100.JimmyWenu.py and DC3.005104.PythiaWenu.py
Mcatnlo samples:
- https://twiki.cern.ch/twiki/bin/view/Atlas/WZMcAtNloSample- Use of DC3.005250.McAtNloWminenu.py and DC3.005254.McAtNloWplusenu.py
38/3118 April 2007 Marc Goulette
Parton selection and event record
Mcatnlo Herwig Pythia
39/3118 April 2007 Marc Goulette
No Photos: effect on acceptancespT
e>25 GeV, pT>25 GeV and ||<2.5:
Almost no effect for ||>1.0 !!
Cut 1.0 2.5
MCATNLO W 16.20 0.16 39.07 0.21
MCATNLO W+ 15.08 0.11 38.64 0.15
MCATNLO W- 17.32 0.12 39.49 0.15
HERWIG W 15.42 0.11 37.13 0.15
HERWIG W+ 14.38 0.14 36.77 0.19
HERWIG W- 16.87 0.18 37.63 0.23
PYTHIA W 14.33 0.11 35.98 0.14
PYTHIA W+ 12.74 0.13 34.61 0.19
PYTHIA W- 16.51 0.17 37.87 0.23
HERWIG/MCATNLO W 95.22 1.17 95.03 0.64
PYTHIA/MCATNLO W 88.47 1.09 92.10 0.62
HERWIG/PYTHIA W 107.60 1.11 103.20 0.59
HERWIG W+ / MC W+ 95.38 1.17 95.15 0.63
PYT W+ / MC W+ 84.51 1.07 89.55 0.60
HERWIG W- / MC W- 97.45 1.22 95.28 0.69
PYT W- / MC W- 95.36 1.19 95.89 0.68
Acceptances in %
Acc
epta
nce
rati
o
_cut
before
Acc
epta
nce
rati
o
_cut
after
40/3118 April 2007 Marc Goulette
McAtNlo events with or without jets
The events with/without Jets have a slightly different shape for the pTw:
Nu
mbe
r of
eve
nts
pTw (MeV/c)
W without jet
W with jet
=> But W+jet is a small fraction of all events (23.7%) and pTw
doesn’t affect much the acceptances (see later…)
41/3118 April 2007 Marc Goulette
McAtNlo weights
Should not be forgotten: weight +1 (91.2%) or -1 (8.8%).N
um
ber
of e
ven
ts
Nu
mbe
r of
eve
nts
pTw (MeV/c)pTw (MeV/c)
Weight +1Weight -1
All
42/3118 April 2007 Marc Goulette
pTw and pT
e
Differenceat low pT
Samebehaviourat high pT
pTw (MeV/c)pTw (MeV/c)
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Rat
ioR
atio
pTe (MeV/c)pTe (MeV/c)
43/3118 April 2007 Marc Goulette
mW invariant massN
um
ber
of e
ven
ts
mW (MeV)
44/3118 April 2007 Marc Goulette
Cos(*)N
um
ber
of e
ven
ts
Cos(*)
V-A compatible
45/3118 April 2007 Marc Goulette
No UE and no ISR (1): HERWIG/MCATNLO
Effect of Underlying Event and ISR on acceptance JIMMY/MCATNLO
0.7000
0.7500
0.8000
0.8500
0.9000
0.9500
1.0000
1 2 3 4 5
ETA cut
ACCEPTANCE
Standard
no UE
no UE no ISR
No real improvement yet …
HERWIG / MCATNLO
46/3118 April 2007 Marc Goulette
No UE and no ISR (2):PYTHIA/MCATNLO
Effect of Underlying Event and ISR on acceptance PYTHIA/MCATNLO
0.8000
0.8200
0.8400
0.8600
0.8800
0.9000
0.9200
0.9400
0.9600
0.9800
1.0000
1 2 3 4 5
ETA cut
ACCEPTANCE
Standard
no UE
no UE no ISR
Some improvement (~+6%)
47/3118 April 2007 Marc Goulette
No UE and no ISR (3): HERWIG/PYTHIA
Effect of Underlying Event and ISR on acceptance JIMMY/PYTHIA
0.8500
0.9000
0.9500
1.0000
1.0500
1.1000
1 2 3 4 5
ETA cut
ACCEPTANCE
Standard
no UE
no UE no ISR
Important effect from UE: needs to be better understood… Discussion with authors has started (M.Seymour, T.Sjostrand)
HERWIG / PYTHIA
48/3118 April 2007 Marc Goulette
No UE and no ISR: mW for all generators
printout From leptons
Pythia
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
~mW (GeV)~mW (GeV)
~mW (GeV)
mWgenmWleptonsSqrt(x1.x2.s)Sqrt(x1.x2.s) is also calculated
later for Herwig and Mcatnlo.
49/3118 April 2007 Marc Goulette
mWgen/mWrec Sqrt(x1.x2.S)/mWgen Sqrt(x1.x2.S)/mWrec
mWrec-mWgen Sqrt(x1.x2.S) - mWgen
PythiamWgen: directly from W, mWrec: from leptons, sqrt(..): from quarks
(MeV) (MeV)
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
50/3118 April 2007 Marc Goulette
mWgen/mWrec Sqrt(x1.x2.S)/mWgen Sqrt(x1.x2.S)/mWrec
mWrec-mWgen Sqrt(x1.x2.S) - mWgen
HerwigN
um
ber
of e
ven
ts
Nu
mbe
r of
eve
nts
(MeV) (MeV)
51/3118 April 2007 Marc Goulette
Pdfs at high xN
um
ber
of e
ven
tsN
um
ber
of e
ven
ts
Nu
mbe
r of
eve
nts
Nu
mbe
r of
eve
nts
xu xd
xc xs
_
_
52/3118 April 2007 Marc Goulette
√(x1.x2.s) for Pythia, no UE, no ISR: no ME vs MEN
um
ber
of e
ven
ts
~mW (GeV)
Matrix Element Correctiondoesn’t seem to affect the
distribution