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Uta Klein Foundation Deutsches Elektronen-Synchrotron

Uta Klein Foundation Deutsches Elektronen-Synchrotron. On the implications on HERA for the LHC physics. HERA and the LHC. Picture of HERA tunnel. University of Bonn Research Seminar, November 2 nd , 2006. Outline. Motivation Inclusive exploration of proton structure

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Uta Klein Foundation Deutsches Elektronen-Synchrotron

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  1. Uta Klein • Foundation Deutsches Elektronen-Synchrotron On the implications on HERA for the LHC physics HERA and the LHC Picture of HERA tunnel University of Bonn Research Seminar, November 2nd, 2006 November 2006Uta Klein - HERA and the LHC

  2. Outline • Motivation • Inclusive exploration of proton structure • High precision QCD fits • Gluons at low x • Charm and beauty • Concluding remarks • Outlook November 2006Uta Klein - HERA and the LHC

  3. ep and pp • ep collisions (HERA) • Ideal tool to study the • structure of hadrons via deep inelastic scattering •  structure functions/parton densities • Can use the photon as a point-like • or hadronic particle through • its virtuality • Main contributions are in the area of QCD: Small-x, diffraction, saturation, high densities, jets… • Precise understanding of QCD • pp collisions (LHC) • Highest energies reachable, • can reach highest masses for new particles production • Precision often limited by knowledge of quark/gluon • structure of proton • QCD effects need to be controlled to the best of our knowledge xp x1p x2p fa fb x = proton momentum fraction of quark November 2006Uta Klein - HERA and the LHC

  4. Tevatron and LHC longer Q2 extrapolation smaller x J.Stirling ICHEP04 November 2006Uta Klein - HERA and the LHC

  5. Physics @ LHC G.Dissertori Lisbon05 “The only place where success appears before work is a dictionary..” Discovery potential relies on precise understanding of QCD. HERA ‘delivers’ partons and understanding of production mechanism. November 2006Uta Klein - HERA and the LHC

  6. Q2=10000 GeV2 g b x~0.005 at central rapidity Inclusive Higgs bosonproduction - SM hep-ph/0508222v1 dominant production process much larger compared to bbarH coupling small in comparison to ttbarH coupling and b-quark distribution function smaller than gluon DF <- input from HERA November 2006Uta Klein - HERA and the LHC

  7. Inclusive Higgs bosonproduction - MSSM hep-ph/0508222v1 beyond the SM approaches, e.g. MSSM : 2 Higgs doublets with 2 independent vacuum expectation values -> ratio of VEV is a free parameter -> couplings to t- and b-quarks are modified -> high values of tanβ will enhance the coupling to the b-quark -> production cross section measurement of Higgs is a KEY ingredient to disentangle new physics note : similar trends for Higgs production at Tevatron! November 2006Uta Klein - HERA and the LHC

  8. Effect of PDF uncertainties onHiggs production cross section hep-ph/0508222v1 TEVATRON LHC 20% αS 2 -> αS 3 NLO -> NNLO 10% PDF uncertainty [ NLO PDFs] Higgs mass November 2006Uta Klein - HERA and the LHC

  9. Effect of PDF uncertainties …cont’d LHC … be aware, uncertainties for g and b are highly correlated 10% hep-ph/0508222v1 -> important to gain better control of PDF uncertainties and to get independent measurements of b and gluon PDFs November 2006Uta Klein - HERA and the LHC

  10. W and Z production HERA-LHC WS procs. • suggested to use as parton luminosity monitor current uncertainties ~ 8% W&Z may be used as SM benchmark measurement but 8% are large compared to theory uncertainty of 1-2% -> need for more precise HERA data, in particular for gluon PDF hep-ex/0509002v1 November 2006Uta Klein - HERA and the LHC

  11. Effect of excluding low x HERA data hep-ph/0509002v4 x1=0.006 x2=0.006 total cross section x1=0.12 x2=0.0003 x1=0.0003 x2=0.12 xmin MRST observed instabilities of NLO QCD fits (tension of low x HERA data and Tevatron inclusive jet data ?) -> not confirmed by CTEQ studies … November 2006Uta Klein - HERA and the LHC

  12. Effect of excluding low x HERA data …cont’d hep-ph/0509002v4 • All well defined if we believe in standard theory at low x. • Are there measurements to further constrain • the parton dynamics at low x? - ‘standard’ Q>2 GeV -- Q>2.5 GeV, x>0.001 -- Q>3.162 GeV,x>0.005 November 2006Uta Klein - HERA and the LHC

  13. November 2006Uta Klein - HERA and the LHC

  14. The H1 Detector 320 authors, 42 institutes Fast Track Trigger Forward Proton and Neutron Spectro- meters Luminosity spectrometer p e 27.5 GeV 920 GeV Forward tracking: Si + DC November 2006Uta Klein - HERA and the LHC

  15. Straw Tube Forward Tracker Micro Vertex Detector The ZEUS Detector Luminosity spectrometer Beam Pipe Magnets 350 authors ~35 institutes November 2006Uta Klein - HERA and the LHC

  16. Luminosity development at HERA I: 92-00 (unpolarized e) II: 03-07 (polarized e) • HERAI: H1 and ZEUS took • about 130pb-1 with HV on • including 16 pb-1 e- data • HERAII “luminosity upgrade” • [lumi ‘on tape’] • 2003/2004: positrons ~50 pb-1 • 2004-06: electrons: ~213 pb-1 • 2006: positrons : so far ~60 pb-1 • 2007: scheduled end of HERA status 1.11.2006 November 2006Uta Klein - HERA and the LHC

  17. Deep inelastic scattering kinematics Neutral Current (NC) interactions • Q2= -q2 : resolving power of the • exchanged boson ~1/√Q2 • ‘DIS’ : Q2 >> M2proton • snapshot of proton structure • x = Q2/2Pq : fraction of proton • momentum carried by struck quark (Bjorken ‘68) • y = Pq/Pk : fraction of lepton momentum carried by the exchange (inelasticity, please • do not mix with the rapidity y!) hadronisation At HERA : NC : kinematics over-constrained (Ee,θe and/or Ejet,θjet) CC : ν escapes detection kinematics from Ejet,θjet November 2006Uta Klein - HERA and the LHC

  18. High Q2 Low x  kinematic limit November 2006Uta Klein - HERA and the LHC

  19. NC and CC cross sections Neutral current Neutral Current e   p Charged current Charged Current e   p  ZEUS (H1) r ≤ 0.85 (1.0) 10-18 m  quarks are point-like down to proton radius/1000 November 2006Uta Klein - HERA and the LHC

  20. DIS structure functions NC CC PDFs below bottom threshold valence quarks November 2006Uta Klein - HERA and the LHC

  21. What HERA DIS data taught us on F2em 1992 data : ∫Ldt ~30nb-1 1997 data : ∫Ldt ~30pb-1 Q2 = 15 GeV2 sea quarks valence quarks e.m. structure of the proton known to few % in a large area of x and Q2 November 2006Uta Klein - HERA and the LHC

  22. PDFs at low x x dependence of q(x,Q2) determined by fit to eNdata, Q2 dependence determined by DGLAP equations: at high x HERA-I: F2/F2~30% November 2006Uta Klein - HERA and the LHC

  23. Reduced charged current cross sections e- e+ _ _ --- s (e-p) ~ x (u+c) + (1-y2) x (d+s) _ _ --- s (e+p) ~ x (u+c) + (1-y2) x(d+s) HERA can disentangle parton distributions at large Q2 and large x > 0.01 within single experiments, independently of nuclear corrections and free of higher twists and isospin assumptions (measure d of the proton directly) November 2006Uta Klein - HERA and the LHC

  24. Unfolding PDFs using CC and NC cross sections jets E.g. ZEUS NLO QCD fit[EPJC42(2005)1] Q2=10 GeV2 Parameterisation: • Constraints: •  momentum and quark number sum rules •  low-x behaviour of uv and dv set equal •   set consistent with Gottfried sum and DY • 11 free parameters in total • heavy quarks treated in variable flavour number scheme of Thorne and Roberts •  uncertainties evaluated using Offset Method EPJ C30(2003)1 November 2006Uta Klein - HERA and the LHC

  25. Sea quarks and gluon ZEUS inclusive NC+CC & jets  improved precision for gluon at medium x November 2006Uta Klein - HERA and the LHC

  26. The strong coupling αSfrom NLO QCD fits ZEUS H1 EPJC42(2005)1 EPJ C21(2001)33 • strong improvement observed from using ep jet data • experimental uncertainties in the range of 2% • both αS values have an additional ‘scale’ uncertainty of 0.005 (4.3%) which • reflects an ad hoc approach to cover beyond NLO effects •  precision of HERA data call for NNL0 QCD analyses • NNLO calculation now available, thanks S.Moch,J.A.M. Vermaseren,A.Vogt [hep-ph/0403192 & 0404111] • deuterons at HERA would disentangle nonsinglet – singlet evolution and further reduce αSerror significantly November 2006Uta Klein - HERA and the LHC

  27. Side remark B.Reisert, DIS03-WS; hep-ph/0601012 (p101) … this chance is now gone for HERA … November 2006Uta Klein - HERA and the LHC

  28. -2006 α@ 10-9 -2006 GF@ 10-5 -2006 G@ 0.02% -2006 αS @ 1-2% Alfas results C. Glasman, hep-ex/0506035 Improved accuracy with more and more accurate data (statistics and systematics), inclusive and jets Theory uncertainty: NNLO, /2? November 2006Uta Klein - HERA and the LHC

  29. Gluons at low x Derivative and F2 determine gluon distribution: but only within DGLAP and not very accurately. FL is necessary to test QCD at h.o. November 2006Uta Klein - HERA and the LHC

  30. FL from reduced inclusive DIS cross section } F2 • extrapolated to low Q2 < 3.5 GeV2 • But H1 determination of FL has two limitations: • small x & FL extraction needs assumptions on F2 • x-dependence of FL can not be determined •  Precision FL measurement requires low-Ep running! FL>0 November 2006Uta Klein - HERA and the LHC

  31. Low energy running proposal … M Klein DIS06 summary Rochester Conference 1955 November 2006Uta Klein - HERA and the LHC

  32. M Klein DIS06 Rosenbluth representation of cross section 920 575 460 GeV F2 F2-FL f(y) L ~ Ep2 10 5 2 pb-1 Binning crucial: used Q2, =sy/2M Choice of 3rd energy value to divide f(y) linearly: 575 GeV if 460 GeV is the lowest energy. At larger x all measurements are at low y (f(y)) and thus the sensitivity to FL decreases rapidly. For full y range a new precise measurement of F2 results. November 2006Uta Klein - HERA and the LHC

  33. M Klein DIS06 H1 : FL simulation of two energies 920 GeV 30 pb-1 460 GeV 10 pb-1 Error between 0.05 and 0.1, statistical and systematics about matched, At high y efficiency and yp background sources of uncertainty similar. November 2006Uta Klein - HERA and the LHC

  34. D Kollar DIS06 ZEUS : Detailed FL simulation of two energies November 2006Uta Klein - HERA and the LHC

  35. J Feltesse Lowx2006 A direct measurement of FL at x from 10-4 to 10-3 is difficult but feasible by running HERA for a few weeks at low proton beam energy. Agreed by both H1 and ZEUS and supported by the PRC. The measurement of FL provides a very attractive added value to the legacy of HERA. It could also provide the first measurement of FLD at the 3-4 sigmas level. Let’s do it. November 2006Uta Klein - HERA and the LHC

  36. U d Q2 (GeV2) extrapolated H1 exp errors! Charm and Bottom M.Klein, BINN-LHC-04 B.Reisert, priv.comm; hep-ph/0601012 (p100) • at x=0.001 • dominated by sea quarks • but valence quark PDFs although small also not well known xG3 from HERA II • dramatic increase of sea PDFs towards high Q2 :c,b sizeable • how to improve knowledge on HQ PDFs? • how well does evolution work? UV dV c b s HERA  LHC November 2006Uta Klein - HERA and the LHC

  37. Charm and beauty in DIS dominated by boson-gluon fusion D* production in DIS November 2006Uta Klein - HERA and the LHC

  38. H1 hep-ex/0507081 F2cc F2bb November 2006Uta Klein - HERA and the LHC

  39. November 2006Uta Klein - HERA and the LHC

  40. Impact parameter tagged • with Si-vertex detector • -> very promising measurements • a challenge for HERA II HERA LHC, e.g. H,Z November 2006Uta Klein - HERA and the LHC

  41. Polarized charged current DIS A.Tapper ICHEP06 text book measurement November 2006Uta Klein - HERA and the LHC

  42. Dependence on Pe November 2006Uta Klein - HERA and the LHC

  43. Limits for MWR November 2006Uta Klein - HERA and the LHC

  44. HERA combined NC measurements NEW : ICHEP06 November 2006Uta Klein - HERA and the LHC

  45. QCD & EW SM analysis New: ICHEP06 November 2006Uta Klein - HERA and the LHC

  46. Concluding remarks • HERA data have been delivering a deeper understanding of p structure as encoded in PDFs and their uncertainties. Those are widely used in the HE community. • First round of measurements and QCD analyses of NC and CC DIS HERA I data is essentially finished. • Further results to come with increasing luminosity, time and precision and employing new techniques and theoretical developments • + inclusion of ep jet data • + inclusion of new polarized HERA II data • + combined EW and QCD analysis • Dedicated run at lower proton energy would allow a first measurement of FL and a direct determination of gluons at low x : scheduled for last 3 months of HERA running • HERA data have a great potential but to reach a next level of precision in PDFs and αS is a serious challenge (systematic ~1%, NNLO…). • These analyses require a few more years of dedicated analyses (also combining H1+ZEUS. • Workshops next year: HERA-LHC [CERN], DIS07[MPI], DIS@TeV[CERN] November 2006Uta Klein - HERA and the LHC

  47. now then November 2006Uta Klein - HERA and the LHC

  48. Kinematics of the Large Hadron electron Collider November 2006Uta Klein - HERA and the LHC

  49. ep collider in the LHC tunnel 70 * 7000 GeV2 further studies at forthcoming workshop cost estimate and design study ready by about 2010 an attractive option for upgrading the LHC physics Search for and spectroscopy of new particles (eq states), new strong i.a. at TeV scale? Exploration of high density QCD High precision ep in LHC range hep ex November 2006Uta Klein - HERA and the LHC

  50. LHeC parameters Compare with HERA: maximum reached was 0.05 1033 cm-2s-1 Estimated luminosities of linac-ring ep colliders below HERA November 2006Uta Klein - HERA and the LHC

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