Pythia and Herwig settings

1
Pythia and Herwig settings
Kt2 PARP(64)(1-z)Q2 LQCD PARP (61)

• ISR setting
• Tune-A PARP(67)4
• Pt(Z) tunning PARP(64)0.2 by Willis (Herwig
  1.0)
• Top/diboson MC production in 4.9.1
• Tune-A PARP(67)4
• Pt(Z) tunning PARP(64) 1.0
• W/Z production MC production in 4.9.1
• Tune-A PARP(67)4 (no effect)
• Pt(Z) tunning PARP(64) 0.2
• Direction for universal setting
• Tune PARP(64) and (61)

m
m-
Q2max K PARP(67)
No effect for S-channel resonances (W/Z/Higgs etc)
2
Pythia settings
Willis Pt(Z) tune
3
MC validations on Pythia Herwig samples
Comparison of mean (MPV) values in Top mass
templates after full simulation
Problem in 5.3.2 Pythia?

• Why is the reconstructed top mass of ttopui still
  same as that of ttopei Pythia sample? though we
  see about 3 GeV increase in HERWIG?
• Lets check the HEPG level

4
Status at HEPG level

• Comparisons of Pt(W), Pt(b-parton), Pt(lepton)
  between Pythia and HERWIG at HEPG level
• Gen 5 Pythia and HERWIG with Mtop178 GeV show
  almost identical distributions,

Comparison of mean (MPV) values in Top mass
templates at HEPG particle levels (smeared jets)

• Pythia ttopui MPV is correct, but mean value is
  wrong ISR/FSR problem?
• Why the mean (and MPV) of Herwig ttopti is higher?

5
Status at HEPG level

• Comparisons of Pt(W), Pt(b-parton), Pt(lepton)
  between Pythia and HERWIG at HEPG level
• Gen 5 Pythia and HERWIG with Mtop178 GeV show
  almost identical distributions,

Comparison of mean (MPV) values in Top mass
templates at HEPG particle levels (smeared jets)
Pythia ttopui MPV is correct, but mean value is
wrong ISR/FSR problem? Why the mean (and MPV) of
Herwig ttopti is higher?
6
Issue in Herwig

• Offline 5.3.2 Herwig 6.504
• But Herwig 6.4 in offline 4.9.1
• Herwig 6.504 with Photon in offline 5.3.3
• Need to validiate Herwig 6.504 ttbar with QED Off
  and Mtop175 GeV (vs V6.4 Herwig ttbar)

7
Comparisons at HEPG
Pt(b) 68.1-gt69.7 4.11.1 -gt5.3.2
Pt(W) 80.7-gt81.8 4.11.1 -gt 5.3.2
Pt(W)Pythis vs Herwig 5.3.2 ( 178 )
Pt(b)Pythis vs Herwig 5.3.2 ( 178 )