Pythia and Herwig settings

Kt 2 = PARP(64)(1-z)Q 2 L QCD = PARP (61) m + m Q 2 max: K PARP(67) • • • • 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) No effect for S-channel resonances (W/Z/Higgs etc)

Willis Pt(Z) tune

Pythia settings

MC validations on Pythia & Herwig samples

Comparison of mean (MPV) values in Top mass templates after full simulation 4.11.1

mean 5.3.2

mean Pythia ttopei(Mt=175) 170.9+-0.2

ttopui(Mt=178) 170.0+-0.3

Herwig ttopli(Mt=175) 170.6+-0.3

ttopti(Mt=178) 173.9+-0.2

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?

 Let’s check the HEPG level

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 Mtop=178 GeV show almost identical distributions, Comparison of mean (MPV) values in Top mass templates at HEPG particle levels (smeared jets) Pythia Herwig 4.11.1

mean MPV 5.3.2

Mean MPV ttopei(Mt=175) 174.7+-0.4

175.2+-0.4

ttopui(Mt=178) 175.8+-0.2

177.3+-0.4

ttopli(175) 174.5+-0.6

175.8+-0.6

ttoppk(170) 170.4+-1.0

ttopsk(180) 179.2+-1.0

ttopti(178) : Pt(b, lepton) same between 180.2+-0.4 ttopti and ttopui 181.0+-0.2

 Pythia ttopui: MPV is correct, but mean value is wrong: ISR/FSR problem?

 Why the mean (and MPV) of Herwig ttopti is higher?

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 Mtop=178 GeV show almost identical distributions, Comparison of mean (MPV) values in Top mass templates at HEPG particle levels (smeared jets) Pythia Herwig 4.11.1

mean MPV 5.3.2

Mean MPV ttopei(Mt=175) 174.7+-0.4

175.2+-0.4

ttopui(Mt=178) 175.8+-0.2

177.3+-0.4

ttopli(175) 174.5+-0.6

175.8+-0.6

ttoppk(170) 170.4+-1.0

ttopsk(180) 179.2+-1.0

ttopti(178) : Pt(b, lepton) same between 180.2+-0.4 ttopti and ttopui 181.0+-0.2

Pythia ttopui: MPV is correct, but mean value is wrong: ISR/FSR problem?

Why the mean (and MPV) of Herwig ttopti is higher?

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 Mtop=175 GeV (vs V6.4 Herwig ttbar)

Comparisons at HEPG

Pt(b): 68.1->69.7

4.11.1 ->5.3.2

Pt(W): 80.7->81.8

4.11.1 -> 5.3.2

Pt(b):Pythis vs Herwig 5.3.2 ( 178 ) Pt(W):Pythis vs Herwig 5.3.2 ( 178 )