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Inclusive & Charm Jets in Neutral Current DIS Events Using the Breit Frame

OUTLINE. Inclusive & Charm Jets in Neutral Current DIS Events Using the Breit Frame. York Weekly Meeting. Jeff Standage York University 24 th November 2004. HEP & QCD HERA & ZEUS Analysis 1: Inclusive Jets in the Breit Frame Analysis 2: Charm Jets

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Inclusive & Charm Jets in Neutral Current DIS Events Using the Breit Frame

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  1. OUTLINE Inclusive & Charm Jets in Neutral Current DIS Events Using the Breit Frame York Weekly Meeting Jeff Standage York University 24th November 2004 • HEP & QCD • HERA & ZEUS • Analysis 1: Inclusive Jets in the Breit Frame • Analysis 2: Charm Jets • Some theory &motivation • Selection of events, jets and D*s • Control plots • Results so far • Outlook and plans York Talk, 24th November 2004 Jeff Standage, York University

  2. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Strong Force (QCD) (Colour) Less well understood. Fundamental parameter: (S ) increases with distance perturbation theory only works at small distances. Boson is self-coupling. Standard Model & QCD Electromagnetic Force (QED) (Charge) Weak Force Unified: Electroweak. Well understood. Fundamental parameter:  (w) known to 14 s.f. small (~1/137) decrease with distance. perturbation theory works well. Bosons not self-coupling. York Talk, 24th November 2004Jeff Standage, York University

  3. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Standard Model & QCD U D U Proton York Talk, 24th November 2004Jeff Standage, York University

  4. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Standard Model & QCD U C D C U Proton York Talk, 24th November 2004Jeff Standage, York University

  5. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Standard Model & QCD WHAT IS IN THE PROTON? U HOW CAN WE TEST THIS? HOW MANY CHARM QUARKS ARE THERE? C D C U ARE THE QCD CALCULATIONS WE CAN DO, ACCURATE? Proton York Talk, 24th November 2004Jeff Standage, York University

  6. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame York Talk, 24th November 2004Jeff Standage, York University

  7. 27.52 GeV electrons Hall West Hall East HERA RING p e Petra Injection Ring 820 (920) GeV protons Hall South Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Hall North HERA York Talk, 24th November 2004Jeff Standage, York University

  8. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame ZEUS York Talk, 24th November 2004Jeff Standage, York University

  9. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame An Event: Feynman Diagram York Talk, 24th November 2004Jeff Standage, York University

  10. e’ e P Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame An Event  , Z0 York Talk, 24th November 2004Jeff Standage, York University

  11. JET JET Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Feynman Diagrams e’ e  , Z0 c Boson Gluon Fusion (BGF)  c s c s P Proton remnant York Talk, 24th November 2004Jeff Standage, York University

  12. e’ e  JET e’ JET e  p Born q z-axis Born Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Feynman Diagrams “LAB” s BGF s p e e’ JET  JET QCD Compton JET s p BREIT JET JET JET QCD Compton JET BGF JET York Talk, 24th November 2004Jeff Standage, York University

  13. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Jargonbuster • Jet: collimated fast moving particles (i.e. all moving in the same direction). • Cross section = Number of X / Luminosity • Luminosity: intensity of the beam. • Differential cross section (w.r.t. A): plot showing how cross-section varies with a variable, A. • Inclusive jet cross-section: cross-section of all jets, as opposed to jets containing a charm quark or events containing two jets (dijet cross-section). • Pseudorapidity, η= -ln(tan(/2),isdirection of a jet or particle w.r.t. beam axis. York Talk, 24th November 2004Jeff Standage, York University

  14. Motivation Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame • This method provides a means of testing pQCD: High-ET jet production is directly sensitive to hard QCD process. • Inclusive cross-section for high-ET jets αs. • Don’t get infra-red sensitive regional problems that can occur in dijets cross-section. • This analysis uses 98-2000 data (82.1 pb-1). • High statistics means a more accurate measurement of αs. York Talk, 24th November 2004Jeff Standage, York University

  15. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame • Standard DIS Event Selection for ZEUS: • Trigger bit b12 and DIS03. • yjb > 0.04 yel < 0.95 • Ee’ > 10 GeV • 40 < E – pz < 60 (GeV) • |zvtx| < 50 cm • PT/(ET1/2) < 2.5 GeV1/2 • where PT is the missing transverse momentum and ET is the total transverse energy both measured in the CAL. Q2 > 125 GeV2 -0.7 < cosγh < 0.5 Selection of DIS Events Annual Committee Review, 23th September 2004Jeff Standage, York University

  16. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Monte Carlo & Detector Simulation • Detector is not perfect: calorimeter imperfections, energy losses in the medium, trigger efficiencies, etc. • Monte Carlo programs generate fake events to first order. • Detector simulation programs simulate the data that would be roduced by the detector if those events really happened. • Need to know that this data is similar to real life because it is used to “correct” the real data. • -> CONTROL PLOTS York Talk, 24th November 2004Jeff Standage, York University

  17. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Control Plots ZEUS 98 - 2000 ARIADNE Q2DA Yele YJB cosγh Selection of DIS Events Ee(corr) zvtx E-pz θe Annual Committee Review, 23th September 2004Jeff Standage, York University

  18. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame JET Selection & Reconstruction • Jets reconstructed from ZUFOs/hadrons boosted into the Breit Frame • KT Cluster algorithm used in inclusive mode. • Jets selected using criteria: • Breit Frame: • Lab Frame: ETL > 2.5 GeV • -1.0 < ηL < 2.0 • Events with a jet “close” to the scattered lepton are rejected. • Events with 1+ jets of ETB>5 GeV located in very backward direction (ηL < -2) are also rejected. ETB > 8 GeV -2.0 < ηB < 1.8 Annual Committee Review, 23th September 2004Jeff Standage, York University

  19. Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame JET Selection & Reconstruction ZEUS 98 - 2000 ARIADNE Breit Jet Control Plots Lab Annual Committee Review, 23th September 2004Jeff Standage, York University

  20. Latest Results Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Inclusive Cross Sections Q2 Annual Committee Review, 23th September 2004Jeff Standage, York University

  21. Latest Results Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Inclusive Cross Sections ET Annual Committee Review, 23th September 2004Jeff Standage, York University

  22. Latest Results Inclusive Jet Cross-Sections in Neutral Current DIS Events Using the Breit Frame Inclusive Cross Sections η Annual Committee Review, 23th September 2004Jeff Standage, York University

  23. Charm Jet Motivation Charm Jet Analysis in Neutral Current DIS Events. • Charm Motivation • Charm jets consist of a charm particle as part of jet. • They can be used to test pQCD. • Jets (containing charm) allows one to get closer to the parton dynamics (hard scatter) of the event, as the actual charm quark/gluons cannot be directly observed. • Photoproduction study shows that the lower two resolved processes (charm from photon) dominate. Is this the same for DIS events? • One can probe the structure of the exchange photon in addition to the proton structure. • Processes for charm-jet events are shown in the next slide. Annual Committee Review, 23th September 2004Jeff Standage, York University

  24. Charm Jet Motivation Charm Jet Analysis in Neutral Current DIS Events. Charm Motivation Resolved Direct Resolved (charm excitation) Annual Committee Review, 23th September 2004Jeff Standage, York University

  25. Selection of DIS Events Charm Jet Analysis in Neutral Current DIS Events. • Standard DIS Event Selection for ZEUS: • Trigger bit b27. • yjb > 0.04 yel < 0.95 • Ee’ > 10 GeV • 40 < E – pz < 60 (GeV) • |zvtx| < 50 cm • PT/(ET1/2) < 2.5 GeV1/2 • where PT is the missing transverse momentum and ET is the total transverse energy both measured in the CAL. Q2 > 1.5 GeV2 Annual Committee Review, 23th September 2004Jeff Standage, York University

  26. Selection of Jets and D*s Charm Jet Analysis in Neutral Current DIS Events. Jet Selection ETL > 4.5 GeV -1.0 < ηL < 2.4 Events with a jet “close” to the scattered lepton are rejected. D* Selection “Golden Decay”: pT(D*) > 3.0 GeV |D*| < 1.5 pT(K) > 0.4 GeV pT() > 0.4 GeV pT(s) > 0.4 GeV |track| < 1.5 1.80 < m(D0) < 1.92 GeV 0.143 < M < 0.148 GeV Annual Committee Review, 23th September 2004Jeff Standage, York University

  27. D* - Jet Matching Charm Jet Analysis in Neutral Current DIS Events. D* - Jet Matching Annual Committee Review, 23th September 2004Jeff Standage, York University

  28. Control Plots ZEUS 96 - 2000 RAPGAP Charm Jet Analysis in Neutral Current DIS Events. Event Control Plots Q2DA Yele xDA Annual Committee Review, 23th September 2004Jeff Standage, York University

  29. Control Plots ZEUS 96 - 2000 RAPGAP Charm Jet Analysis in Neutral Current DIS Events. D* Control Plots Annual Committee Review, 23th September 2004Jeff Standage, York University

  30. Control Plots ZEUS 96 - 2000 RAPGAP Charm Jet Analysis in Neutral Current DIS Events. Jet Control Plots Annual Committee Review, 23th September 2004Jeff Standage, York University

  31. ZEUS Data 96-2000 Wrong charge background Fit Charm Jet Analysis in Neutral Current DIS Events. Initial Results 541  32 D*s candidates. Annual Committee Review, 23th September 2004Jeff Standage, York University

  32. Charm Jet Analysis in Neutral Current DIS Events. Outlook and Plans: • The next steps in this analysis are as follows: • The D*/Jet acceptance corrections need to be calculated to correct for detector effects. • Hadron-Parton and QED corrections need to be calculated for the jets. • Differential cross-sections will be calculated. • NLO calculations need to be done for theoretical predictions for comparison of theory with experimental results. • Systematic checks and statistical errors need to be assessed, including use of different MC generators. Future Steps Annual Committee Review, 23th September 2004Jeff Standage, York University

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