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Insights into Diffractive Di-Jet Production and Inclusive Diffraction

Discover updates on diffraction phenomena in high-energy collisions, including diffractive di-jet production and W/Z boson events. Explore recent data from CMS collaboration presentations at the MB/UE Workshop. Analyze cross sections, event displays, and comparison with simulation results using various generators (Pythia6, Pythia8, Phojet). Findings highlight the importance of diffractive components in understanding particle interactions.

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Insights into Diffractive Di-Jet Production and Inclusive Diffraction

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  1. Update on diffraction • Inclusive diffraction • Diffractive di-jet production: event displays • Diffractive W and Z production: event displays M. Arneodo (Univ. Piemonte Orientale, Novara, and INFN Torino) on behalf of the CMS collaboration MB/UE Workshop, 8 Feb 2011

  2. Forward instrumentation at CMS CMS Hadronic Forward (HF) Hadronic Forward (HF) (3.0 < || < 5.0) 140m 140m (5.2 < || < 6.6) CASTOR ZDC ZDC (|| > 8.1) (|| > 8.1) Hadron Forward: HF • @11.2m from interaction point (3 < || < 5) • Steel absorbers/quartz fibers (Long+short fibers) (3.2 < || < 4.6) BSC

  3. Inclusive diffraction Single-diffractive dissociation (SD): Double-diffractive dissociation (DD): Central-diffractive dissociation (CD): • PAS FWD-10-001: Observationofdiffraction at 900 and 2360 GeV • (published in June 2010) • PAS FWD-10-007: Observationofdiffraction at 7 TeV NB All distributions uncorrected !

  4. Event Selection/Acceptance • Early run at 7 TeV, L=20mb-1 (<NPU>0) • Trigger: beam pick-ups (BPTX) + hit in BSC counters (on either side) • Event selection: • - high-quality primary vertex (ndof>4) • - beam-halo and beam background rejection • - calorimeter-noise cleaning • =protonfractional • momentum loss • Very low xeventsrejectedby • vertexrequirement • Largediscrepancybetween • generators (more to come)

  5. Evidence of inclusive diffraction (I) • Inclusive diffractive cross section peaks at small proton momentum loss: σ ~ 1/ξ • ξΣ(E +pz) for scattered p in +ve z direction • ξΣ(E -pz) for scattered p in -ve z direction Uncorrected ! Observed diffraction via diffractive peak

  6. Evidence of inclusive diffraction (II) • Inclusive diffraction characterised by large rapidity gap No energy deposition in HF ie gap over HF Zero tower multiplicity in HF ie gap over HF Uncorrected ! Uncorrected ! Observed diffraction via large rapidity gap

  7. Inclusive diffraction vs s 900 GeV 2.36 TeV 7 TeV Inclusive diffraction & diffractive dijets 7

  8. Data vs MC

  9. Data vs MC (forward: 3<|h|<5) Uncorrected ! Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet ok ok ok very bad ok bad very bad

  10. Data vs MC (cal |h|<3) Uncorrected ! Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet fair fair fair bad ok fair very bad

  11. Data vs MC (cal |h|<3) Uncorrected ! Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet fair fair fair bad ok fair very bad

  12. Data vs MC (cal |h|<3) Uncorrected ! Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet fair fair fair bad ok fair very bad

  13. Data vs MC (tracking |h|<2.4) Uncorrected ! pT>0.5 GeV Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet bad bad bad fair fair ok bad

  14. Enhance diffr. component: data vs MC (forward) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Uncorrected ! Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet bad bad bad bad bad bad fair (but not low E)

  15. Enhance diffr. component: data vs MC (tracking) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p ! Uncorrected ! (only at high pT) Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet bad bad bad fair fair ok fair

  16. Summary of data vs MC comparison • Distributionswithoutdiffractiveenhancement: • Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet • CAL |h|<3 fair fairfair bad ok fair very bad • Tracking bad badbad fair fair ok bad • Forward ok fair fair bad fair bad bad • 2) Distributionswithdiffractiveenhancement • Tracking bad badbad fair fair ok fair • Forward bad badbadbadbadbad fair • No single MC describes the data in their entirety • Diffraction best reproduced by Phojet and Pythia8 (in central region) • Inclusive distributions best reproduced by Pythia6 (Z1 in central region, D6T in forward) and Pythia8

  17. p p p jet jet LRG Diffractive dijet production EventDisplays: DPS note DP-2010-036

  18. Diffractive dijet candidate at 7 TeV DPS note DP-2010-036 pT (jet1) = 41.2 GeV, pT (jet2) = 31.9 GeV η (jet1) = -2.8, η (jet2) = -3.3 E(η < 3.0) > 1.5 GeV pT(track) > 0.5 GeV E(η ≥ 3.0) > 2.0 GeV 3

  19. W, Z LRG Diffractive W & Z production Eventdisplays [DPS note DP-2011-01 ]

  20. Diffractive W candidate at 7 TeV DPS note DP-2011-01

  21. Diffractive Z candidate at 7 TeV DPS note DP-2011-01

  22. Summary • Diffraction “re-discovered” at 7 TeV – results complement • those at 900 and 2360 GeV from 2009 • Uncorrected data compared with Pythia6, Pythia8 and Phojet • in central (calorimeter and tracking) and forward regions • Phojet/Pythia8 give better description of diffractive-enhanced • distributions • Pythia6 does not describe the diffractive component • Hard diffraction there…

  23. BACKUP

  24. Forward instrumentation at CMS HF 3 ≤|| ≤ 5 (CMS) Castor5.3 ≤ || ≤ 6.6(CMS)

  25. Data vs MC (forward: 3<|h|<5) Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet ok ok ok very bad ok bad very bad

  26. Data vs MC (forward: 3<|h|<5) Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet fair fair fair very bad fair bad very bad

  27. Data vs MC (tracking |h|<3) SD dominates at small values of pT, Ntrack, SpT

  28. Enhance diffr. component: data vs MC (tracking) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Pythia6 D6T Pythia 8 Phojet bad ok fair

  29. Enhance diffr. component: data vs MC (tracking) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Pythia6 D6T Pythia 8 Phojet bad ok fair

  30. Enhance diffr. component: data vs MC (tracking) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Pythia6 D6T Pythia 8 Phojet bad ok fair

  31. Enhance diffr. component: data vs MC (tracking) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet bad bad bad fair fair ok fair

  32. Enhance diffr. component: data vs MC (tracking) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet bad bad bad fair fair ok fair

  33. Enhance diffr. component: data vs MC (forward) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Non-diffractive contribution suppressed

  34. Enhance diffr. component: data vs MC (forward) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Non-diffractive contribution suppressed

  35. Enhance diffr. component: data vs MC (forward) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Non-diffractive contribution suppressed

  36. Enhance diffr. component: data vs MC (forward) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet bad bad bad bad bad bad fair (but not low E)

  37. Enhance diffr. component: data vs MC (forward) Look at events with eg no activity in HF+ (ie rapidity gap over HF, E(HF+) < 8 GeV) LRG p Pythia6 D6T DW CW P0 Z1 Pythia 8 Phojet bad bad bad bad bad bad fair (but not low E)

  38. E+pz vs E-pz

  39. HF+ vs HF-

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