Generator Study of W(mn)g @ Tevatron collider

2 vs. 3 body W(mn)gamma and CSRD Motivation: precise test of RAZ of SM, and probe ATGC in both photon pT and RAZ Both call for on-shell W, cascade decaying leptonically, i.e. 22 2body final states. This is what Pythia does; but experimentally, what observed in m+n+g, and under on-shell W assumption predicted by Pythia Radiation Amplitude Zero (RAZ) Charge Signed Lepton Photon Rapidity Difference (CSRD) in Tevatron Lab frame in Wg rest frame Blue stands for Pythia in all slides

Distort of CSRD and dphi The correct treatment of m+n+g 3-body final states, including lepton FSR and interference, as CompHep (here I assume Baur-LO gives the same results as CompHep) On-shell W Events by Pythia8 FSR-inclusive Events by Comphep Significant difference of 2- and 3-body treatment M(mn) CSRD off-shell effects in 23 Distort of CSRD and dphi M(mng) dphi(mg)

Photon PT >10, Muon PT > 20, Neutrino PT > 20, Kinematic cuts to “restore” Pythia? Photon PT >10, Muon PT > 20, Neutrino PT > 20, dR > 0.7, MT(lng)>110GeV W- Events by Pythia8 W- Events by Comphep Photon pT Muon pT Neutrino pT dR(mg)

Photon PT >10, Muon PT > 20, Neutrino PT > 20, dR > 0.7, MT >110GeV W- Events by Pythia8 W- Events by Comphep M(mn) M(mng) MT(mng)

Photon PT >10, Muon PT > 20, Neutrino PT > 20, dR > 0.7, MT >110GeV W- Events by Pythia8 W- Events by Comphep Photon eta Muon eta dphi(mg) CSRD This CSRD plot is in consistent with previous result, where a plain instead of peak in the right was seen, see next slide

Charge Signed Lepton Photon Rapidity Difference Plots of Different Cut On-shell W Events MT3 >110GeV Events MT3 >100GeV Events MT3 >90GeV Events Photon PT >10GeV Lepton PT >20GeV Missing ET >20GeV dR>0.7 Charge Signed Lepton Photon Rapidity Difference

Conclusion 1 + 3-body FRS and interference differs from on-shell Wgamma production and lepton decay + Cuts as MT>110GeV will suppress off-shell effect, and give good photon pT agreement, but dphi and CSRD of lepton and photon + Question: we see dphi and CSRD difference of Wgamma-LO and Pythia, how can we trust a 2-body NLO QCD Wgamma-NLO?

Parameters used in Comphep vs. WGAMMA 3 body consistency: CompHep vs BaurLO Parameters used in Comphep vs. WGAMMA Beam type ppbar Energy (TeV) 1.96 PDF CTEQ6L αem 1/132.43 M(W) 80.41 M(Z) 91.188 sin2θw 0.22242 Гw 2.103

Photon PT >5GeV, dR(l,γ) > 0.7 W- Events by Comphep + + + + W- Events by WGAMMA Photon PT >5GeV, dR(l,γ) > 0.7 Photon Pt Muon Pt Neutrino Pt dR(muon,photon)

Photon PT >5GeV, dR(l,γ) > 0.7 W- Events by Comphep + + + + W- Events by WGAMMA M(mn) M(mng) MT(mng)

Photon PT >5GeV, dR(l,γ) > 0.7 W- Events by Comphep + + + + W- Events by WGAMMA Photon Eta Muon Eta Dphi(mg) CSRD