1. Physics with Muon and Hadron Beams at COMPASS Reiner Geyer for the COMPASS collaboration Hadron Structure 2009

2. Daniele Panzieri 2 EINN07 - Milos 12-15 september 2007 N SPS LHC SPS Beams: protons up to 400 GeV/c. 4.8s/16.2 spill Secondary hadron beams (p,π ±,K ± ) with 2·10 8 particles/spill Tertiary Muons: 2·10 8 particles/spill with 80% polarization

3. Hadron Structure 2009 3 The COMPASS Collaboration Bielefeld, Bochum, Bonn (HISKP), Bonn (PI), Burdwan and Calcutta, CERN, Dubna (LPP and LNP), Erlangen, Freiburg, Mainz, Lisbon, Moscow (INR), Moscow (LPI), München (LMU), München (Technische Universität), Prague, Protvino, Saclay, Tel Aviv, Torino (University and INFN), Trieste (University and INFN), Warsaw (SINS), Warsaw (TU), Yamagata 240 Physicists from more than 20 Institutes Experiments with Muon Beam -ΔG/G 1 -g 1 -Transverse Spin Effects -Flavor Decomposition of Spin Distribution Functions -Excl. Vector Meson Production -Lambda Polarizations Future: -DVCS Experiments with Hadron Beams -Pion and Kaon Polarizabilities -Diffractive Production of Exotic States -Search for Glueballs -Light Meson Spectroscopy Future: -Drell Yan

4. Historical Overview 2002, 2003, 2004, 2006 and 2007 data taking with 160 GeV, polarized μ beams: –2002-2006 6LiD polarized target (~polarized deuterons) –2007 NH3 polarized target (~polarized protons) –Both longitudinal and transverse polarized targets. 2000 TB of data corresponding to 5·10 10 events Pilot run in 2004 for hadron program Few days of effective data taking. 2008: Hadron Beams for diffractive scattering. Physics Results Muon Beams: ΔG/G, ΔΣ, Transversity, Flavor Decomposition, Pentaquark, Exclusive Production of Vector Mesons, Cahn Asymmetries. Hadron Beams: PWA in diffractive Scattering. South Africa, November 2007 4

5. Polarized Deep Inelastic Scattering Hadron Structure 2009 5

6. The First Moment of g 1 first moment of g 1 “Spin crisis” EMC 1987 Contrary to naive expectations, the spin of the nucleon is not only carried by the quarks.

7. Hadron Structure 2009 7

8. From COMPASS Hadron Structure 2009 8 Error is a factor 2 bigger without COMPASS NLO QCD Fit of world data ΔΣ = Δu + Δd + Δs =0.30 ± 0.01(stat)±0.02(evol)

9. Hadron Structure 2009 Where is the Proton Spin From the pattern of the spin structure functions we expect more generally: Experiment ΔΣ = Δu + Δd + Δs

10. Flavor decomposition of Nucleon Structure South Africa, November 2007 10 Alexander Korzenev: Measurement of the Spin Structure of the Proton by COMPASS

11. Hadron Structure 2009 11 Direct measurement of ΔG/G Two approaches to tag PGF in COMPASS q = c: Open Charm D 0, D * decay q = u, d, s: High- p t Hadron Pairs Photon Gluon Fusion (PGF) Photon Gluon Fusion Spin dependence of the basic-processes calculable via pert. QCD

12. ΔG/G from High p t Hadron Pairs Hadron Structure 2009 12 Q 2 >1 Dominated by: Open charm production dominated by PGF: Cleanest but most difficult to measure!

13. Hadron Structure 2009 Open charm at COMPASS Photon-gluon fusion: 1.2 D 0 per PGF cc event c c g BR 4 % D 0 from D * about 20 % or:

14. Hadron Structure 2009 14 The Compass Spectrometer SM1 SM2 Beam MuonWall E/HCAL RICH Target Two-stage spectrometer Tracking: VSAT+SAT+LAT Particle Id: RICH,  Calorimetry: ECAL, HCAL ~250000 channels up to 580 TB/year recorded Two-stage spectrometer Tracking: VSAT+SAT+LAT Particle Id: RICH,  Calorimetry: ECAL, HCAL ~250000 channels up to 580 TB/year recorded  /h beam: 160/190 GeV high beam intensity large angular acceptance broad kinematical range  /h beam: 160/190 GeV high beam intensity large angular acceptance broad kinematical range 50 m

15. Hadron Structure 2009 15 The Compass Spectrometer

16. Particle ID - The RICH Hadron Structure 2009 16

17. Kπ Mass Spectrum Hadron Structure 2009 17

18. Hadron Structure 2009 18 ΔG/G Results Interest in Orbital Momentum GPDs

19. Physics with Transverse Spin Hadron Structure 2009 19 Christian Schill: Transversity Measurements at COMPASS Stefano Takekawa: Spin physics in polarized Drell-Yan processes at COMPASS

20. Meson Spectroscopy Hadron Structure 2009 20

21. Exotic States ? Hadron Structure 2009 21 Hybrids Candidates Glueball Candidates

22. Diffractive Scattering and Central Production Hadron Structure 2009 22

23. First Results from the 2004 Pilot Run Hadron Structure 2009 23

24. PWA Technique Hadron Structure 2009 24

25. Waves used in step 1of PWA South Africa, November 2007 25

26. Major Waves Hadron Structure 2009 26

27. π 1 (1600) Hadron Structure 2009 27

28. COMPASS in 2008 Hadron Structure 2009 28

29. Target Region Hadron Structure 2009 29

30. Trigger Hadron Structure 2009 30

31. Statistics in 2008 Hadron Structure 2009 31 π - p  π - π + π - π + π - p, π - π 0 π 0 p, π - ηηp, π - π 0 p; K - p  K - π + π - p Matthias Schott: Physics with Kaons in the Final State

32. Hadron Run 2009 Hadron Structure 2009 32 Spectroscopy with positive beam –p beam with 25% pions, 190 GeV, LH2 target –“Central production” Spectroscopy with negative beam –π − beam with 3% kaons, 190 GeV, LH2 target –Diffraction with LH2 target (low t) –Diffraction with nuclear target –Primakoff Scattering Studies for future program (needed for delevopments) –DVCS test with muon beam and recoil det. –Drell-Yan test with π - beam

33. Proposal to Study DVCS at COMPASS Hadron Structure 2009 33

34. Kinematical Range at COMPASS Hadron Structure 2009 34

35. Feasibility Studies 2008 Hadron Structure 2009 35 1 day measurement 1/3 μ-intensity 1/6 of target length

36. Summary Muon Program –New results on polarized PGF and gluon polarizations. –New results on Transversity  Christian Schill. –New results on flavor decomposition of nucleon structure. –More data taking on longitudinal and transversal polarized proton target (2010 & 2011) in order to improve statistics. Hadron Program –Results on diffractive 3 π production from 2004 pilot hadron run. –A lot of new results to be expected from 2008 and 2009 on diffractive scattering and central production in different final states. Feasibility studies for DVCS and Drell Yan ongoing. Proposal under preparation. If successful data taking from ~ 2012 on. Hadron Structure 2009 36

37. More Talks from COMPASS @ HS2009 Christian Schill: Transversity Measurements at COMPASS Alexander Korzenev: Measurement of the spin structure of the proton by COMPASS Alexey Guskov: The possibility of pion polarizabilities measurements at COMPASS Matthias Schott: Studies of Kaonic final states at COMPAS Stefano Takekawa: Spin Physics in polarized Drell-Yan processes at COMPASS Ekaterina Perevalova: Logitundinal polarisation of the Λ and Λ-bar hyperons in DIS @ COMPASS South Africa, November 2007 37