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HERA and the H1 experiment Inclusive deep inelastic scattering and jets

Physics with H1 at HERA II. Max Klein DESY Zeuthen. ?. HERA and the H1 experiment Inclusive deep inelastic scattering and jets Low x and the evolving view on parton dynamics Further new physics Leave searches, pdf‘s, electroweak, ... for RY.

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HERA and the H1 experiment Inclusive deep inelastic scattering and jets

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  1. Physics with H1 at HERA II Max Klein DESY Zeuthen ? • HERA and the H1 experiment • Inclusive deep inelastic scattering and jets • Low x and the evolving view on parton dynamics • Further new physics • Leave searches, pdf‘s, electroweak, ... for RY MK - H1 in HERA II, 2. 10. 2003 Ringberg Workshop, October 2nd, 2003

  2. HERA • H1 goals for HERA II High luminosity: 1fb-1 e+ and e-, polarised change of Ep MK - H1 in HERA II, 2. 10. 2003

  3. HERA and the LHC QCD, searches, p structure 4pi multipurpose detectors MK - H1 in HERA II, 2. 10. 2003

  4. (Upgrades of) the H1 Detector for HERA II 36 institutes, 320 authors 210 postdocs data taking since 1992 Fast Track Trigger Very Forward Proton Spectro- meter VFPS Luminosity spectrometer p e 27.5 GeV 920 GeV Forward tracking: Si + DC MK - H1 in HERA II, 2. 10. 2003

  5. 2. Inclusive Deep Inelastic Scattering and Jets deep inelastic neutral current scattering event in the H1 apparatus yp Spacal p e‘ e 27.5 GeV 920 GeV Silicon Strips Drift chambers e+ LAr calorimeter DIS s=4EeEp=100000 GeV2 MK - H1 in HERA II, 2. 10. 2003

  6. event shapes & QCD resummed Inclusive jets: well described by NLO QCD MK - H1 in HERA II, 2. 10. 2003

  7. HERA II 500pb-1 e+ 500pb-1 e- expected HERA I 100pb-1 e+ 15pb-1 e- measured g-Z interference: e- constructive / e+ destructive500 pb-1:10 % cross section error for Q2 > 16.000 GeV2 you can never have enough luminosity to beat 1/Q^4 and (1-x)^3 MK - H1 in HERA II, 2. 10. 2003

  8. Charged currents HERA II Unfolding of parton distributions using CC and NC cross sections difficult to reach very large x>0.7 reduced cc cross section 2500 GeV2 700 GeV2 e+, 250pb-1 7000 GeV2 25000 GeV2 e-, 250pb-1 _ _ --- s (e-p) ~ x (u+c) + (1-y2) x (d+s) _ _ --- s (e+p) ~ x (u+c) + (1-y2) x(d+s) x x MK - H1 in HERA II, 2. 10. 2003

  9. helicity suppression in charged currents e+ beam polarisation measured in February 2003 simulations: x MK - H1 in HERA II, 2. 10. 2003

  10. parity violation in neutral currents simulation x singlet MK - H1 in HERA II, 2. 10. 2003

  11. DIS measurement of alpha_s - with H1 and BCDMS data 0.1150 ± 0.0019 (exp+fit) ± 0.0050 (ren.scale) joint determination of alphas, xg, V,A no interest in quarks  two pdfs only 9 F2 = 3 xV +11xA = 4xU+xD • chi2+1 well defined two consistent exp data sets MK - H1 in HERA II, 2. 10. 2003

  12. the BCDMS data determines all DIS determinations of the strong coupling, BUT shifts imposed by QCD fit to BCDMS data alphas (BCDMS) very low and strongly y dependent („electron method“) low y – large x region in conflict with SLAC F2 systematic errors of BCDMS data MK - H1 in HERA II, 2. 10. 2003

  13. run at minimum possible proton beam energy access large x at lower Q2 x=0.07 simulation 460 GeV*27.5 GeV 30 pb-1 x=0.10 x=0.14 W2=20GeV x=0.18 x=0.23 x=0.25 x=0.35 x=0.45 x=0.55 Measurements at low y: • Simulation of resonance region • Low noise calorimetry • Forward tracking BCDMS data x=0.65 y=0.3 at 280 GeV MK - H1 in HERA II, 2. 10. 2003

  14. Correlation of alphas and xg is resolvable in DIS fits with HERA data  determination of alphas and of the gluon distribution inclusive DIS fits yield very small gluon density at large x  must fail to describe Tevatron jets MK - H1 in HERA II, 2. 10. 2003

  15. 3. Low x and the evolving view on parton dynamics high density low x and parton emission diffraction heavy flavours skewed parton distributions MK - H1 in HERA II, 2. 10. 2003

  16. strong scaling violations at low x lead to very large gluon momentum density xg depends on c treatment! xg is not an observable  no unique determination and still uncertain at low x, Q2!  Higher precision, more constraints (FL, charm, J/Psi and Y ~ xg2) MK - H1 in HERA II, 2. 10. 2003

  17. HERA II simulation Longitudinal structure function H1 prel simulation of low Ep data [~ 460, 575, 920 GeV] MK - H1 in HERA II, 2. 10. 2003

  18. forward jet and particle production forward jets in BFKL region DIS: Q2 >5 GeV2 dijets: azimuthal decorrelation NLO 3-jets in trouble at lowest x CCFM (unintegrated g) and CDM ok x MK - H1 in HERA II, 2. 10. 2003

  19. Diffractive ep Scattering: large and puzzling part of the cross section Smashed in DIS but “intact” in diffraction ? MK - H1 in HERA II, 2. 10. 2003

  20. concept works in charm and jet production in ep MK - H1 in HERA II, 2. 10. 2003

  21. HERA II …it doesnt at the Tevatron H1: extended instrumentation of upstream p beam region spectator i.a.’s break p? soft colour interactions? G.Ingelman Blois 03 MK - H1 in HERA II, 2. 10. 2003

  22. Deeply Virtual Compton Scattering NLO LO beautiful events, signature interferes with Bethe Heitler e Colour Dipol Models Generalised Parton Distributions MK - H1 in HERA II, 2. 10. 2003

  23. beam spin asymmetry  pol. e beams ALU ~ sign(e) • Im (BH•DVCS*) sin Φ beam charge asymmetry  e+-e- AC ~ Re (BH•DVCS*) cos Φ Map proton wave function in DIS (large Q2) region and at low x (cf HERMES) Access to H structure function  angular momentum part of proton spin (Ji) A.Freund hep-ph/0306012 MK - H1 in HERA II, 2. 10. 2003

  24. theory of heavy flavour production HERA II • mid x (CST), extend to low x (BST) and large x (FST) • high statistics through luminosity upgrade and Fast Track Trigger for photoproduced charm  requires further theoretical development (NLO) MK - H1 in HERA II, 2. 10. 2003

  25. simulation 200pb-1 MK - H1 in HERA II, 2. 10. 2003

  26. measure energy (W) dependence of cross sections, VM production … run at minimum possible proton beam energy MK - H1 in HERA II, 2. 10. 2003

  27. HERA II • High statistics and precision • Lifetime tags MK - H1 in HERA II, 2. 10. 2003

  28. Summary HERA has dramatically expanded our view on the structure of the proton and the strong interactions yet We still don’t know well enough xg at low and large x, alpha_s, uv, dv, s, c, b in HERA’s range How to formulate the theory of DIS at high parton densities The nature of diffraction or heavy flavour production We have just started to explore Beauty physics Correlations between (within) diffraction, HQ and jets Generalised parton distributions Extreme regions of phase space (hi t, hi pt, hi x) We will open new fields with much increased luminosity, polarisation and changed beam energies such as searches, collider (single) spin physics, elw. space like physics… We need HERA longer than currently envisaged to study Confinement (low x,Q2), saturation (eA), neutron structure (eD), spin MK - H1 in HERA II, 2. 10. 2003

  29. Summary MK - H1 in HERA II, 2. 10. 2003

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