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

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

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

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

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

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

7. E. Tassi - DESY PRC, 30 October 2002 7 Background Studies 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

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

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

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

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

12. E. Tassi - DESY PRC, 30 October 2002 12 ZEUS-O e  p,110 pb -1 ZEUS-S u v,d v QCD Fit, High-Q 2 NC and CC ZEUS NLO QCD Fit Now published Now published Zeus PDFs with uncertainties and  s Zeus PDFs with uncertainties and  s Zeus-Only valence PDFs Zeus-Only valence PDFs High Q2 NC and CC analyses e+p NC/CC approaching completion e+p NC/CC approaching completion - will complete ZEUS HERA I inclus.cross sections measurements at high-Q 2 - will complete ZEUS HERA I inclus.cross sections measurements at high-Q 2 Important input for: Important input for: -Testing the EW sector of the SM -Testing the EW sector of the SM -Learn more about valence PDFs at high-x -Learn more about valence PDFs at high-x ZEUS/H1 working group established and doing good progress...  s (Mz) =0.1166  0.0008  0.0032  0.0036  0.0018 uncor. corr. norm. model

13. 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 Q 2 > 125 GeV 2 and E B T,jet > 8 GeV and compared to NLO QCD predictions. As a result of a QCD fit:  precise determination of  s (M Z ) 96/97 data set, incl. K  in the Breit frame

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

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

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

17. E. Tassi - DESY PRC, 30 October 2002 17 Beauty production b visible cross sections in PHP  (ep  bbX  e Jet Jet  X)  (ep  bbX  e Jet Jet  X) Q2 <1 GeV 2, 0.2< y <0.8 Q2 <1 GeV 2, 0.2< y <0.8 At least two jets in the Lab frame with: P T,jet1(jet2) > 7(6) GeV,  jet  7(6) GeV,  jet  < 2.5 At least on muon with: At least on muon with: p T,  > 2.5 GeV, -1.6 2.5 GeV, -1.6 <   <2.3 New result:96/00 ~98 pb -1 3 times more statistics Data/NLO ~1.4 Data/NLO ~1.4 Agreement within uncertainties

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

19. E. Tassi - DESY PRC, 30 October 2002 19 Deeply Virtual Compton Scattering Simple process: a diffractively produced real photon Great theoretical interest: Great theoretical interest: - Generalized Parton Distributions - Generalized Parton Distributions....but also Color Dipole Models,....but also Color Dipole Models, VM production VM production  (  *p  p) measured as a function of Q 2 and W in e + p and e - p

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

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

22. E. Tassi - DESY PRC, 30 October 2002 22 Search for isolated  s Prompted by high pt-lepton searches Prompted by high pt-lepton searches (electron and muon channels) (electron and muon channels) H1 see excess, ZEUS compatible H1 see excess, ZEUS compatible with the Standard Model with the Standard Model Look at the  channel... 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)

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

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

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