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ZEUS Status

DESY PRC, 30 October 2002. ZEUS Status. E. Tassi, NIKHEF. Software/Detector status 2002 Running: Background studies Physics Results Outlook. ZEUS Computing. Computer farm: Recently upgraded with 40 Intel Xeon/2.2 GHz processors - doubled system´s computing power.

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ZEUS Status

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  1. DESY PRC, 30 October 2002 ZEUS Status E. Tassi, NIKHEF • Software/Detector status • 2002 Running: • Background studies • Physics Results • Outlook

  2. ZEUS Computing Computer farm: Recently upgraded with 40 Intel Xeon/2.2 GHz processors - doubled system´s computing power Mass Storage System: Moved from SSF to dCache (DESY/FNAL) - cached access to the storage system and CPU upgrade have greatly improved turnaround of analysis jobs 16 Mio of events processed so far... E. Tassi - DESY PRC, 30 October 2002

  3. ZEUS Application Software ZeViS Zeus Visualization Package • Since the first „slim release“ rapidly becoming a mature product • Among new features • Full event information • Improved 2D/3D rendering • New detectors included • -FTD/STT/RTD/MUON • Used as front-end of the • online event display Already an invaluable tool E. Tassi - DESY PRC, 30 October 2002

  4. ZEUS detector status • Detector operational - 2000 components re-commisioned - Since Feb. 22 could operate CTD (although at lower beam currents - Background) • Concentrate on new components: Photon Cal. and Lumi Spectrometer Straw-Tube Tracker Zeus Micro Vertex Detector E. Tassi - DESY PRC, 30 October 2002

  5. LUMI and STT LUMI • Photon Cal. and spectrometer both taking data and measuring luminosity • Calibration/alignement/acceptance studies on-going • STT • Integrated in the data taking • STT s/w in the reconstruction suite • After installation a few h/w problems • were identified. Detailed plan to cure • them has been elaborated. E. Tassi - DESY PRC, 30 October 2002

  6. Micro Vertex Detector • Succesfully taking data • MVD reconstruction code thoroughly exercised/tuned • Global Tracking Trigger running and producing first results • Preparation for the final alignement well underway E. Tassi - DESY PRC, 30 October 2002

  7. Background Studies • Huge effort devoted by the collaboration (see ZN-02-018 and forthcoming addenda) • Main concern: operating the CTD • Background sources: positron-beam related: SR,e-gas proton-beam related: p-gas • Our present understanding and possible remedies E. Tassi - DESY PRC, 30 October 2002

  8. Synchrotron radiation and e-gas Design: C5a with integrated shield Synchrotron Radiation • Direct (marginal) and backscattered photons entering CTD and producing ionization • Exploit detailed simulation suite • Factor ~10 should be achievable by implementing shielding measures and modification of beamline elements Fairly good understanding of the problem.. • e-gas • Origin of the problem... • C5a reduced thickness: • only factor 2 reduction • Need improvement of the vacuum lower momentum e E. Tassi - DESY PRC, 30 October 2002

  9. proton-gas • Will become the main source of BG when reducing SR • MC simulation implementing p-gas (HERWIG minimum bias) - mainly sensitive to 20m from IP - vacuum profile from MC/Data comp. • Dynamic vacuum • Marginal improvements from modification of our beamline Need much improved vacuum (especially close to the IR) E. Tassi - DESY PRC, 30 October 2002

  10. @ nominal Ie=58 mA @ nominal Ip=130 mA p-gas total p-gas total e-gas e-gas synch synch A Possible Scenario Ie=50ma Ip~130mA Ie~60mA E. Tassi - DESY PRC, 30 October 2002

  11. Physics Results ZEUS rich physics program: 45 contributed papers to ICHEP 2002 Highlights: • QCD fits, High-Q2 NC and CC cross sections • DIS inclusive jet cross sections • Beauty production • Deeply Virtual Compton Scattering • Searches for isolated taus and missing Pt HERA II Physics: see K. Long and P.Schleper last PRC´s presentations E. Tassi - DESY PRC, 30 October 2002

  12. ZEUS-S uv,dv ZEUS-O ep,110 pb-1 QCD Fit, High-Q2 NC and CC ZEUS NLO QCD Fit • Now published • Zeus PDFs with uncertainties and s • Zeus-Only valence PDFs s(Mz) =0.1166  0.00080.00320.00360.0018 uncor. corr. norm. model • High Q2 NC and CC analyses • e+p NC/CC approaching completion • - will complete ZEUS HERA I inclus.cross sections measurements at high-Q2 • Important input for: • -Testing the EW sector of the SM • -Learn more about valence PDFs at high-x • ZEUS/H1 working group established and doing good progress... E. Tassi - DESY PRC, 30 October 2002

  13. NC DIS inclusive jet cross sections • Direct sensitivity to s and the gluon density • Reduced theoretical unc. w.r.t. dijet cross sections (infrared insensitive) Analysis: Single and double differential cross measured for Q2 > 125 GeV2 and EBT,jet > 8 GeV and compared to NLO QCD predictions. As a result of a QCD fit:  precise determination of s (MZ) 96/97 data set, incl. K in the Breit frame E. Tassi - DESY PRC, 30 October 2002

  14. NC DIS inclusive jet cross sections Agreement at high-Q2 and high-ET,jet E. Tassi - DESY PRC, 30 October 2002

  15. Inclusive jet cross sections E. Tassi - DESY PRC, 30 October 2002

  16. Boson-Gluon Fusion (direct) Gluon-Gluon Fusion (resolved photon) Beauty Production Rich testing ground of QCD - NLO pQCD: FMNR (PHP), HVQDIS (DIS) - DGLAP vs CCFM evolution - Fragmentation ZEUS contributing with a set of precise measurements in the PHP and DIS regimes E. Tassi - DESY PRC, 30 October 2002

  17. Beauty production b visible cross sections in PHP (epbbX e Jet Jet  X) Q2 <1 GeV2, 0.2< y <0.8 At least two jets in the Lab frame with: PT,jet1(jet2) > 7(6) GeV, jet < 2.5 At least on muon with: pT, > 2.5 GeV, -1.6 <  <2.3 New result:96/00 ~98 pb-1 3 times more statistics Data/NLO ~1.4 Agreement within uncertainties E. Tassi - DESY PRC, 30 October 2002

  18. Beauty production First diff. B visible cross sections in DIS (epbbX e Jet  X) Q2 < 2 GeV2, 0.05< y <0.7 At least one jet in the Breit frame with: ET,jet1 > 6 GeV, jet < 2.5 At least one muon with: pT, > 2.0 GeV, 30º <  < 160º New result: 99/00 ~ 60 pb-1 Agreement with NLO E. Tassi - DESY PRC, 30 October 2002

  19. Deeply Virtual Compton Scattering Simple process: a diffractively produced real photon Great theoretical interest: - Generalized Parton Distributions ....but also Color Dipole Models, VM production (*p p) measured as a function of Q2 and W in e+p and e-p E. Tassi - DESY PRC, 30 October 2002

  20. DVCS • No differences between e+ and e- samples • Steep rise with W  hard underlying process E. Tassi - DESY PRC, 30 October 2002

  21. DVCS Data precise enough to start discriminating different theoretical models. See also hep-ph/0208160 E. Tassi - DESY PRC, 30 October 2002

  22. Search for isolated s • Prompted by high pt-lepton searches (electron and muon channels) H1 see excess, ZEUS compatible with the Standard Model • Look at the  channel... • Search for hadronic  decays • (65% BR, predominantly in one charged hadron) • Analysis based on a Multi-observable discrimination technique • (use 6 jet-shape releted variables) • Aim: separate -induced jets from quark- and gluon-initiated jets • (-jets pencile like, low charged particle multiplicity and charge 1) E. Tassi - DESY PRC, 30 October 2002

  23. Search for isolated s Results 2 events observed (PT>25) 0.12  0.02 expected from SM E. Tassi - DESY PRC, 30 October 2002

  24. Summary and Outlook • Zeus taking data and in good shape • Huge effort devoted to background studies • ZEUS rich physics program well underway • Looking forward to the forthcoming data taking period... E. Tassi - DESY PRC, 30 October 2002

  25. CTD ~ 7*Ie+1.26*Ie 1.3 synch+e-gas synch e-gas CTD ~ 1.17*Ie+0.63*Ie 1.3 e-gas synch spool E. Tassi - DESY PRC, 30 October 2002

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