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PHYSICS RESULTS FROM COMPASS

PHYSICS RESULTS FROM COMPASS. F. Bradamante University of Trieste and INFN Trieste on behalf of the Collaboration Workshop on Hadron Structure at J-PARC November 30, 2005.

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PHYSICS RESULTS FROM COMPASS

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  1. PHYSICS RESULTS FROM COMPASS F. Bradamante University of Trieste and INFN Trieste on behalf of the Collaboration Workshop on Hadron Structure at J-PARC November 30, 2005

  2. COmmon Muon and Proton Apparatusfor Structureand Spectroscopy NA58 Czech Republic, Finland, France, Germany, India, Israel, Italy, Japan, Poland, Portugal, Russia Bielefeld, Bochum, Bonn, Burdwan, Calcutta, CERN, Dubna, Erlangen, Freiburg, Heidelberg, Helsinki, Lisbon, Mainz, Miyazaky, Moscow, Munich, Nagoya, Prague, Protvino, Saclay, Tel Aviv, Torino, Trieste, Warsaw 28 Institutes, ~230 physicists F. Bradamante, Workshop on Hadron Structure, J-PARC

  3. Experiments with muon beam ΔG/G g1 Transverse spin effects Flavor decomposition of spin distribution functions Vector meson production Spin transfer inΛ-hyperon production Experiments with hadron beams Pion and Kaon polarizabilities Diffractive production of exotic states Search for glueballs Light meson spectroscopy Production of double charmed baryons Physics program of COMPASS F. Bradamante, Workshop on Hadron Structure, J-PARC

  4. luminosity: ~5 . 1032 cm-2 s-1 beam intensity: 2.108 µ+/spill (4.8s/16.2s) beam momentum: 160 GeV/c longitudinally polarised muon beam longitudinally or transversely polarised target calorimetry particle identification LHC SPS N F. Bradamante, Workshop on Hadron Structure, J-PARC

  5. 160 GeVμ SM2 SM1 6LiD Target The Spectrometer Trigger-hodoscopes μFilter ECal & HCal 50 m RICH MWPC Straws TWO STAGE SPECTROMETER: Gems Drift chambers Polarized beam and target Micromegas SAT, LAT, PID Silicon SciFi 0.003 < x < 0.5 10-3 < Q2 < 10 GeV2 F. Bradamante, Workshop on Hadron Structure, J-PARC

  6. 160 GeV, polarized m beam6LiD polarized target (~polarized deuterons) 3·1010 events ~ 1000 TB WHERE ARE WE ? • in 2002, 2003, and 2004 COMPASS has taken data in themuon program configuration • pilot run in 2004 for hadron program • 2005: no beam • physics results • DG/G • DS • Transversity • Pentaquark • Exclusive ρ0 • Λ physics F. Bradamante, Workshop on Hadron Structure, J-PARC

  7. physics results ΔG/G F. Bradamante, Workshop on Hadron Structure, J-PARC

  8. N DG/G at COMPASS Photon Gluon Fusion q = c cross section differencein charmed meson production → theory well understood → experiment challenging q = u,d,s cross section difference in 2+1 jet productionin COMPASS: events with 2 hadrons with high-pt → experiment easy → theory more difficult F. Bradamante, Workshop on Hadron Structure, J-PARC

  9. ΔG/G from Open Charm F. Bradamante, Workshop on Hadron Structure, J-PARC

  10. D* (2002) MKpp - (MKp + Mp) (MeV) MKpp - (MKp + Mp) [MeV/c2] ΔG/G from Open Charm - 1 MKpp - (MKp + Mp) [MeV/c2] MKp - MD0(PDG) [MeV/c2] F. Bradamante, Workshop on Hadron Structure, J-PARC

  11. D0 D* (2002) (2002) MKpp - (MKp + Mp) (MeV) MKp - MD0(PDG) [MeV/c2] MKpp - (MKp + Mp) [MeV/c2] ΔG/G from Open Charm - 2 MKpp - (MKp + Mp) [MeV/c2] MKp - MD0(PDG) [MeV/c2] F. Bradamante, Workshop on Hadron Structure, J-PARC

  12. D0 (2002) 400 events D0 (2003) 1100 events COMPASS preliminary COMPASS preliminary D0 (untagged, 2003)4200 events D0 (untagged, 2002) 1400 events COMPASS preliminary COMPASS preliminary ΔG/G from Open Charm - 3 F. Bradamante, Workshop on Hadron Structure, J-PARC

  13. D G = - ± 1 . 08 0 . 73 @ x = 0.15 ± 0.08 g G ΔG/G from Open Charm - 4 First measurement of ΔG/G with Open Charm tagging with 2004 data: 0.73  0.43 F. Bradamante, Workshop on Hadron Structure, J-PARC

  14. ΔG/G from High-pt hadron pairs F. Bradamante, Workshop on Hadron Structure, J-PARC

  15. QCD- Compton PGF LO DIS ΔG/G from High-pt hadrons, Q2 > 1 (GeV/c)2- 1 PGF and background F. Bradamante, Workshop on Hadron Structure, J-PARC

  16. ΔG/G from High-pt hadrons, Q2 > 1 (GeV/c)2- 2 Data – Monte Carlo (LEPTO) comparison Q2 leading hadron: p leading hadron: pt F. Bradamante, Workshop on Hadron Structure, J-PARC

  17. Gluon polarisation with 2004 data: 0.31 0.22 ΔG/G from High-pt hadrons, Q2 > 1 (GeV/c)2- 3 Results from Monte Carlo: Ratio of PGF events F. Bradamante, Workshop on Hadron Structure, J-PARC

  18. QCD- Compton PGF LO DIS ΔG/G from High-pt hadrons all Q2 F. Bradamante, Workshop on Hadron Structure, J-PARC

  19. QCD- Compton PGF LO DIS ΔG/G from High-pt hadrons all Q2 low Q2 resolved photon F. Bradamante, Workshop on Hadron Structure, J-PARC

  20. 0 0.1 0.2 0.3 PGF QCD-C LO DIS qq‘→ qq‘ qg→ qg gg→ gg low pt direct resolv. g ΔG/G from High-pt hadrons, Q2 < 1 (GeV/c)2- 1 Results from PYTHIA Background • as forQ2 > 1 (GeV/c)2 • additional background from resolvedphoton events • additional processes sensitive to gluonsin the nucleon neglect LO DIS and low pt F. Bradamante, Workshop on Hadron Structure, J-PARC

  21. ΔG/G from High-pt hadrons, Q2 < 1 (GeV/c)2- 2 Determination of ΔG/G 2002 + 2003:ALL/D = 0.002 ± 0.019stat. ± 0.003syst hep-ex/0511028, CERN-PH-EP/2005-049, Phys. Lett. B with 2004 data: 0.089 0.06 F. Bradamante, Workshop on Hadron Structure, J-PARC

  22. 2 1 3 GRSV2000 with1 G = 2.5 2 G = 0.6 3 G = 0.2 DG/G from high-pt: results 2002-2003 data results favour small ΔG or ΔG crosses 0 around xg ≈ 0.1 hep-ex/0511028accepted PLB preliminary Glück et al.,Phys. Rev. D63(2001) 094005 F. Bradamante, Workshop on Hadron Structure, J-PARC

  23. g1d F. Bradamante, Workshop on Hadron Structure, J-PARC

  24. g1 of the deuteron (2002-2003) Phys Lett B 612 (2005) 154 • most precise measurement for 0.004 < x < 0.03 • new NLO QCD fit, precision of a0 improves factor 2 (Q2 = 4 GeV2) F. Bradamante, Workshop on Hadron Structure, J-PARC

  25. Transversity single hadron two hadrons Λ F. Bradamante, Workshop on Hadron Structure, J-PARC

  26. Transversity – single hadron - 1 Collins and Sivers angles • C = h- S’ S = h- S S ’ azimuthal angle of spin vector of fragmenting quark (S’’ = p- S) hazimuthal angle of hadron momentum F. Bradamante, Workshop on Hadron Structure, J-PARC

  27. Transversity – single hadron- 2 first measurements of transverse spin asymmetries in DIS of high energy muons on a transversely polarizeddeuteron target published single hadron asymmetries from 2002 run • Collins: related to transverse quark distributions • Sivers: related to intrinsic kT Phys Rev Lett 94 (2005) 202002 F. Bradamante, Workshop on Hadron Structure, J-PARC

  28. Transversity: two hadrons - 1 F. Bradamante, Workshop on Hadron Structure, J-PARC

  29. Transversity: two hadrons - 2 all +/- combinations • precise measurement of few % • systematics seems well under control • also compatible with zero • interesting to see proton in 2006 F. Bradamante, Workshop on Hadron Structure, J-PARC

  30. Transversity: two hadrons - 2 1 +/- combination per events: pt ordering 2002-2003 data weighted average with h1 always positive F. Bradamante, Workshop on Hadron Structure, J-PARC

  31. Transversity: Λpolarization 2002-2003 data F. Bradamante, Workshop on Hadron Structure, J-PARC

  32. Pentaquark search F. Bradamante, Workshop on Hadron Structure, J-PARC

  33. Φ(1860) Pentaquark search - 1 motivated by NA49 report of pentaquark candidate • COMPASS has large sample of the double-strange Ξ– baryon (18000 Ξ–, 11000 Ξ+) from 2002-2003 data • search for Ξ–π–resonance Φ(1860)– – → Ξ–π–→ Λπ–π–→pπ–π–π– F. Bradamante, Workshop on Hadron Structure, J-PARC

  34. Ξ(1530)0 Ξ(1530)0 Φ(1860) Pentaquark search - 2 compare to yields • opposite-sign pairs: Ξ(1530)0 → Ξ– π+ , 1700 and 920 evts • like-sign pairs: evts <79 and <89 at 99% CL (expected ~400) Eur Phys J C41 (2005) 469 F. Bradamante, Workshop on Hadron Structure, J-PARC

  35. Exclusive ρ0production F. Bradamante, Workshop on Hadron Structure, J-PARC

  36. Exclusive ρ0production(2002 data) - 1 F. Bradamante, Workshop on Hadron Structure, J-PARC

  37. 0.01 < Q² < 0.05 < Q² < 0.3 < Q² < 0.6 < Q² < 2.0 < Q² 0.01 < Q² < 0.05 < Q² < 0.3 < Q² < 0.6 < Q² < 2.0 < Q² < 10 GeV2 Exclusive ρ0production- 2 ANGULAR DISTRIBUTIONS preliminary, statistical errors only, limited by MC corrected for acceptance, smearing and efficiency (MC:DIPSI gen) background not subtracted F. Bradamante, Workshop on Hadron Structure, J-PARC

  38. 0.01 < Q² < 0.05 < Q² < 0.3 < Q² < 0.6 < Q² < 2.0 < Q² < 10 GeV2 2002 Exclusive ρ0production - 3 measurement of r 04 00 distribution : Spin density matrix element: Tλρλγare helicity amplitudes meson photon F. Bradamante, Workshop on Hadron Structure, J-PARC

  39. 0.01 < Q² < 0.05 < Q² < 0.3 < Q² < 0.6 < Q² < 2.0 < Q² < 10 GeV2 Exclusive ρ0production- 4 measurementof rand Im r 0 4 1-1 3 1-1 distribution : beam polarisation Spin density matrix element: if SCHC holds weak violation F. Bradamante, Workshop on Hadron Structure, J-PARC

  40. Longitudinal polarization of Λ and antiΛ in DIS F. Bradamante, Workshop on Hadron Structure, J-PARC

  41. ’+ V1 p V2  + q - ΛPOLARIZATION (2002 data) - 1 Event selection F. Bradamante, Workshop on Hadron Structure, J-PARC

  42. ΛPOLARIZATION 2002 data F. Bradamante, Workshop on Hadron Structure, J-PARC

  43. ΛPOLARIZATION 2002 data F. Bradamante, Workshop on Hadron Structure, J-PARC

  44. NEAR FUTURE (2006-2010) Workshop on Future Physics @ COMPASS Yellow Report CERN-2004-011, 22 Nov. 2004 • IMPORTANT UPGRADE of the SPECTROMETER ONGOING RICH TRACKING E.M. CALORIMETERS O. D. P.T. MAGNET Veto System • 2006 MUON RUNNING 100 days 6LiD Longitudinal Polarization 30 days NH3 Transverse Polarization • 2007 HADRON RUNNING CENTRAL PRODUCTION with 300 GeV hadron beam and LH2 target • 2008- 2010 COMPLETE THE APPROVED MUON and HADRON PROGRAMME F. Bradamante, Workshop on Hadron Structure, J-PARC

  45. SUMMARY AND OUTLOOK • a technically challenging new experiment is IN OPERATION SINCE 2002 • a privileged situation at CERN • FIRST PHYSICS RESULTS have been producedMANY MORE IN THE PIPE-LINE • COMPASS is foreseen to run up to the end of the present mid-term plan of CERN (2010) BIG DISCOVERY POTENTIAL • with some upgrade COMPASS might be an interesting option even in the second decade of this century F. Bradamante, Workshop on Hadron Structure, J-PARC

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