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In-Depth Analysis of Exclusive ρ0 Electroproduction by A. Levy

Explore the detailed research findings on exclusive ρ0 electroproduction by A. Levy from Tel Aviv University and Moscow State University, focusing on various parameters and control plots. The study discusses the transition from 'soft' to 'hard' processes, and presents data analysis and systematics adjustments to improve accuracy.

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In-Depth Analysis of Exclusive ρ0 Electroproduction by A. Levy

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  1. Exclusive ρ0 electroproduction H. Abramowicz, S. Kananov, A. Kreisel, A. Levy, O. Smith Tel Aviv University and S. Proskuryakov Moscow State University A. Levy: rho electroproduction

  2. g g IP ‘hard’ ‘soft’ Why are we measuring • Expect  to increase from soft (~0.2, from ‘soft Pomeron’ value) to hard (~0.8, from xg(x,Q2)2) • Expect b to decrease from soft (~10 GeV-2)to hard (~4-5 GeV-2) A. Levy: rho electroproduction

  3. ZEUS published results DESY 98-107, EPJ C6 (1999) 603 A. Levy: rho electroproduction

  4. b(Q2) A. Levy: rho electroproduction

  5. Preliminary results -2001 Arik  BaBar A. Levy: rho electroproduction

  6. Decision: publish 96-00 data • Data: 96-97 (Arik, Sergey) + 98-00 (Sergey, Sasha) L ~ 120 pb-1 • MC: ρ0 – ZEUSVM, pdiss: EPSOFT(96-97), PYTHIA(98-00) using FPC and LPS • Kinematic region: 2 < Q2 < 160 GeV2 32 < W < 180 GeV 0 < |t| < 1 GeV2 • 0.65 < M() < 1.2 GeV - 65,000 evts A. Levy: rho electroproduction

  7. M() - all A. Levy: rho electroproduction

  8. M() – Q2, t A. Levy: rho electroproduction

  9. Control plots Example: 98-00 data A. Levy: rho electroproduction

  10. Control plots – SCHC reweighting Example: 98-00 data A. Levy: rho electroproduction

  11. Control plots – 15ME reweighting A. Levy: rho electroproduction

  12. Density matrix elements A. Levy: rho electroproduction

  13. LPS FPC Proton dissociation MC: PYTHIA A. Levy: rho electroproduction

  14. Systematics • E-PZ cut (default 45 GeV) was changed to 42 and 48 GeV • pT of the pions (default 0.15 GeV) was changed to 0.2 GeV • elasticity cut. The energy of unmatched island (default 0.3 GeV) was changed to 0.25 and 0.35 GeV • elasticity cut. The distance of closest approach of island and extrapolated track was changed from 30cm (default) to 20cm • Z-vertex cut (default |Z| < 50cm) was varied from 40 to 60 cm • Box cut (default 13.2X8 cm) was increased by 0.5 cm •  mass window (default 0.65-1.2 GeV) was changed to 0.6-1.1 GeV • generated W dependence in MC was reweighted by Wn, (n=±0.03) • generated t in MC was reweighted by exp(bt) b = ±0.5 GeV-2 • angular distributions in MC were reweighted according SCHC. Default reweighting comes from 15 matrix element fit. • generated Q2 in MC was reweighted by (Q2+Mρ2)k,where k = ±0.05 A. Levy: rho electroproduction

  15. d/dt A. Levy: rho electroproduction

  16. (Q2) Fit to whole Q2 range gives bad 2/df (~14) Good fit A. Levy: rho electroproduction

  17. (Q2) A. Levy: rho electroproduction

  18. (Q2) n=n(Q2) because b=b(Q2) In case of J/ b=const  n=const A. Levy: rho electroproduction

  19. (W) A. Levy: rho electroproduction

  20. R=L/T (Q2) SCHC A. Levy: rho electroproduction

  21. R(W) • L has the same W dependence as T ?? L  qqbar in small configuration T  qqbar in small and large configurations small configuration  steep W dep large configuration  slow W dep   large qqbar configuration is supressed A. Levy: rho electroproduction

  22. Comparison of analyses A. Levy: rho electroproduction

  23. Outlook • Finish Pomeron trajectory on combined data • Present d/dt in finer bins • Put theory curves on results • ZEUS-note + draft of paper are being written • Try for “paper presentation” before DIS07 A. Levy: rho electroproduction

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