1. Tobias Haas: Recent results from HERA The Dynamics of Proton Structure: Recent Results from HERA 23 August, 2005 Tobias Haas Deutsches Elektronensynchrotron

2. 23 August 2005Tobias Haas: Recent Results from HERA This Talk Introduction to HERA Introduction to HERA Standard model physics Standard model physics NC/CC electrons/positrons, +/- helicities NC/CC electrons/positrons, +/- helicities Very high x cross sections Very high x cross sections Heavy quarks Heavy quarks F 2, F 3, F 2 c, F 2 b F 2, F 3, F 2 c, F 2 b Parton densities Parton densities α S (M Z ) α S (M Z ) EW parameters EW parameters Beyond the standard model Beyond the standard model Quark compositeness Contact interactions Leptoquarks High p T leptons Summary and conclusions Summary and conclusions

3. 23 August 2005Tobias Haas: Recent Results from HERA : 920 GeV : 27.5 GeV ~ 6.3 km circumference 50 TeV on fixed target HERA: The Greatest Electron Microscope Resolution: 10 -18 m

4. 23 August 2005Tobias Haas: Recent Results from HERA Luminosity, e  and polarization = HERA II Polarization: Polarization: 50% reached routinely now 50% reached routinely now > 200 pb -1 /expt delivered > 200 pb -1 /expt delivered Both lepton species Both lepton species Expect ~ 700 pb -1 /expt by the end of HERA (2007) Expect ~ 700 pb -1 /expt by the end of HERA (2007) 50% Polarization (%)

5. 23 August 2005Tobias Haas: Recent Results from HERA DIS @ HERA

6. Tobias Haas: Recent results from HERA Standard Model

7. 23 August 2005Tobias Haas: Recent Results from HERA Neutral Currents Charged Currents Charged and Neutral Currents

8. 23 August 2005Tobias Haas: Recent Results from HERA Charged Currents SM expectation: σ ± (P e ) = (1± P e ) σ ± (P e =0) Right-handed currents are absent

9. 23 August 2005Tobias Haas: Recent Results from HERA Neutral Currents: The Expectation

10. 23 August 2005Tobias Haas: Recent Results from HERA Neutral Currents: First Results 30.5 pb -1 53.5 pb -1 Very promising … HERA 2008

11. 23 August 2005Tobias Haas: Recent Results from HERA What do we learn? NC Cross Sections CC Cross Sections High E T Jet Cross Sections Structure Function Fits Parton Densities αS(μ)αS(μ) EW Parameters NC

12. 23 August 2005Tobias Haas: Recent Results from HERA Structure Functions xF 2 (x)

13. 23 August 2005Tobias Haas: Recent Results from HERA NC cross section @ very high x High precision measurement up to x = 1

14. 23 August 2005Tobias Haas: Recent Results from HERA xF 3 (x)

15. 23 August 2005Tobias Haas: Recent Results from HERA F 2 cc vs Q 2 F 2 bb vs Q 2 Charm and beauty in the proton?

16. 23 August 2005Tobias Haas: Recent Results from HERA xF 2 b (x) and xF 2 c (x)

17. 23 August 2005Tobias Haas: Recent Results from HERA Parton Densities Error on the xg(x) Parton Densities

18. 23 August 2005Tobias Haas: Recent Results from HERA HERA Parton Densities @ LHC Ref: HERA-LHC WS QCD evolution

19. 23 August 2005Tobias Haas: Recent Results from HERA  S (M Z ) Simultaneous determination of α S (M Z ) Simultaneous determination of α S (M Z ) and PDFs α S (M Z ) Due to inclusion of jet cross sections α S (M Z ) and PDFs are NOT strongly correlated

20. 23 August 2005Tobias Haas: Recent Results from HERA Precision of  S (M Z ) @ HERA HERA α S may soon dominate the world average

21. 23 August 2005Tobias Haas: Recent Results from HERA Light quark couplings From H1 PDF fits including additional EW parameters

22. 23 August 2005Tobias Haas: Recent Results from HERA W Propagator Mass & Coupling G F HERA space-like (q 2 0) one HERA space-like (q 2 0) one SM relationship between M W and G F not used SM relationship between M W and G F not used

23. 23 August 2005Tobias Haas: Recent Results from HERA M W and M t in the SM 178±4.3 GeV 80.425±0.038 GeV W mass value: M W =80.786 ± 0.205 exp GeV + the world average M Z  indirect determination of sin 2  W =1  M 2 W /M 2 Z =0.2151 ± 0.0040 exp Top quark mass: m t =104 ± 44 exp GeV  First determination in DIS at EW scale

24. Tobias Haas: Recent results from HERA Beyond the SM

25. 23 August 2005Tobias Haas: Recent Results from HERA Are quarks “elementary”? Form factor measurement at Q 2 ~ 40000 GeV 2 Form factor measurement at Q 2 ~ 40000 GeV 2 Resolution 1/Q ~ 10 -16 cm = 0.001 proton radius Resolution 1/Q ~ 10 -16 cm = 0.001 proton radius Compare measured to expected cross section Compare measured to expected cross section Limits on quark size Limits on quark size H1: H1: R q < 1.0 x 10 -16 cm ZEUS: ZEUS: R q < 0.85 x 10 -16 cm

26. 23 August 2005Tobias Haas: Recent Results from HERA Is there TeV scale physics? (Contact Interactions) Limits on Λ up to 6.2 TeV (Depending on models)

27. 23 August 2005Tobias Haas: Recent Results from HERA Are there leptoquarks? HERA: HERA: s-channel eq fusion s-channel eq fusion resonance in eq (νq) invariant mass in NC (CC) events resonance in eq (νq) invariant mass in NC (CC) events no excess observed no excess observed TEVATRON: TEVATRON: LQ pair production LQ pair production LEP2: LEP2: virtual in e + e - → hadrons virtual in e + e - → hadrons

28. 23 August 2005Tobias Haas: Recent Results from HERA Puzzle: High p T lepton events Signature: Signature: lepton + missing p T + large p T (had) lepton + missing p T + large p T (had) Dominant SM process: Dominant SM process: on-shell W production (σ~1pb) on-shell W production (σ~1pb) Excess seen in HERA I in H1 for e/μ and in ZEUS for  Excess seen in HERA I in H1 for e/μ and in ZEUS for 

29. 23 August 2005Tobias Haas: Recent Results from HERA High p T leptons: Latest numbers H1 update with HERA II data (74 pb -1 e  P) H1 update with HERA II data (74 pb -1 e  P) 6 new electron events with p T (had) > 25 GeV 6 new electron events with p T (had) > 25 GeV no new muon event no new muon event overall excess in e+μ channel overall excess in e+μ channel  search at H1  search at H1 no excess seen (HERA I only) no excess seen (HERA I only)

30. 23 August 2005Tobias Haas: Recent Results from HERA Summary and Conclusions HERA QCD results on structure functions, pdfs and α S are becoming me most precise … HERA QCD results on structure functions, pdfs and α S are becoming me most precise … … but HERA is not only a QCD machine: … but HERA is not only a QCD machine: expect important contributions to EW precision measurements expect important contributions to EW precision measurements excellent search potential excellent search potential … the really good stuff is still to come! … the really good stuff is still to come! C. Gwenlan