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RECENT COMPASS RESULTS ON TRANSVERSE PHYSICS

RECENT COMPASS RESULTS ON TRANSVERSE PHYSICS. Takahiro Iwata Yamagata University. on behalf of the COMPASS Collaboration. COMPASS presentations L-Spin : Celso Franco Future plans: Norihiro Doshita.

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RECENT COMPASS RESULTS ON TRANSVERSE PHYSICS

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  1. RECENT COMPASS RESULTS ONTRANSVERSE PHYSICS Takahiro IwataYamagata University on behalf of the COMPASS Collaboration COMPASS presentations L-Spin : Celso Franco Future plans: Norihiro Doshita Circum-Pan-Pacific Symposium on High Energy Spin Physics, Cairns, Australia, June 20-24 , 2011

  2. OUTLINE • Introduction to COMPASS • The experimental setup • Data taking history • Transverse spin and TMD effects • Asymmetries with a polarized proton target • Azimuthal asymmetries in unpolarized SIDIS • Summary Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  3. ＣＯＭＰＡＳＳ　ａｔ　CERN Lake LEMAN Nucleon Structure Hadron Spectroscopy LH C COMPASS Airport SPS (p:450GeV) CERN (France) N CERN (Suisse) 09/06/2014 BEACH08 26 june 2008 3 Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  4. THE SPECTROMETER • two stage spectrometer • Large Angle Spectrometer (SM1) • Small Angle Spectrometer (SM2) • tracking, calorimetry, PID Configuration in Muon program SciFi Silicon Micromegas GEMs Straws SDC MWPC W45 MuonWall SM2 E/HCAL E/HCAL 0.003 < x < 0.5 10-3 < Q2 < 10 GeV2 SM1 MuonWall Polarised Target RICH • Pol. • beam • 160GeV, • pol. 80% • high energy beam • broad kinematical range • large angular acceptance Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  5. THE POLARIZED TARGET SYSTEM Solid polarized target operated in Dynamic Nuclear Polarization technique with a dilution refrigerator PT magnet: +180~-180 mrad geometrical acceptance To match larger acceptance: 3 target cells: reduction of false asymmetries Target: NH3 for proton , 6LiD for deuteron  longitudinal & transverse mode available very long relaxation time (∼ 4000 h) magnetic field rotation without polarization loss  Polarization of NH3-92%, +88%, -83% Downstream Middle Upstream Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  6. 3 m 6 m photon detectors 5 m C4F10 THE RICH DETECTOR • radiator gas:C4F10 • mirror wall: 20 m2 surface • photon-detectors: • outer part (75%) MWPC(pad RO) with CsI cathode • inner part(25%) 576 MAPMTs with indiv. telescope threshold momenta • pp = 2 GeV/c • pK = 9 GeV/c • pP =17 GeV/c Installed in 2005, Used in data taking from 2006 Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  7. DATA TAKING HISTORY 2002 - 2011 • 2002 Data taking started • muon program with160 GeV polarized muon • 2002-20066LiD polarized target ( pol. deuterons) • L-mode: 80 / T-mode: 20 , DG/G measurement • 2005 no data taking • 2007NH3 polarized target (pol. protons) • L-mode: 50 /T-mode: 50 • 2008, 2009 hadron programwith hadron beam at 190 GeV • 2010 NH3 polarized target (pol. protons) only T-mode • 2011 ditto only L-mode Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  8. Transverse Spin and TMD Effects Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  9. TRANSVERSE SPIN &TMD EFFECTS IN COMPASS DTq(x) = q↑↑(x) - q↑↓(x) Transversity PDF quark with spin parallel to the nucleon spinin a transversely polarized nucleon from Collins asym. in SIDIS single hadron production, two-hadron asym. ,transverse L polarization, … TMD effects angular distributions caused by the parton’s transverse momentum • related to orbital angular momentum of quark from Sivers asym. in SIDIS, azimuthal distribution of hadrons in unpolarized SIDIS Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  10. Transverse Spin Effects Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  11. SINGLE HADRON ASYMMETRIES IN SIDIS fS= azim. angle of nucleon spin (initial quark spin) fS’= azim. angle of struck quark spin fS=p-fS’（due to helicity conservation) fh= azim. angle of leading hadron SIDIS cross-section for transv. PT Sivers Collins Collins angle: Azim. angle of a hadron wrt struck quark spin FC =fh - fS’ (=fh +fS-p) Sivers angle:Azim. angle of a hadron wrt nucleon spin FS=fh - fS nucleon spin (initial quark spin) struck quark spin Scattering plane quark direction hadron （Breit frame） Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  12. COLLINS ASYMMETRY Collins Asymmetry Modulation wrt the Collins angle ± : opposite orientation of the transverse spin of the nucleon PT is the target polarization; DNNis the transverse spin transfer coefficient initial  struck quark, given by QED Transvesity Collins fragmentation function Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  13. COLLINS ASYMMETRIES proton h+ h− PLB 692 (2010), 240 deuteron h+ h− PLB 673 (2009), 127 ・large asymmetry for proton : about 10% , for both h+ and h- ・　deuteron result  opposite sign of DTu and DTd Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  14. NEW RESULTS FOR p & K proton +- large asymmetry for p But, not clear for K proton K+- Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  15. COMPASS-HERMES COMPARISON in good agreement proton - + COMPASSHERMES for charged pions Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  16. TRANSVERSITY GLOBAL FITS • Fitting to AColld from COMPASS, ACollp from HERMES • and Collins F.F. from BELLE (e+e- scattering)  predictions • good agreement with the new proton data of COMPASS • ・　DTu and DTd have opposite sign as expected from deuteron data COMPASS proton 2007 Transvesity u d Anselmino et al. Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  17. TWO-HADRON ASYMMETRY f i h l-l’ Two hadrons produced in SIDIS Modulation wrt the angle between two-hadron plane and struck quark spin Two-hadron asymmetry f : target dilution facto PT: target polarization DNN: transverse spin transfer coefficient initial  struck quark • fS= angle of nucleon spin • (=initial quark spin) • fS’= angle of final (struck) quark spin • fS=p - fS’（due to helicity conservation) • fR = angle of two-hadron plane • fRS=fR –fS’= fR+fS-p nucleon spin (=initial quark spin) quark direction Trento conventions see hep-ph/0407345 Breit frame Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  18. TWO-HADRON ASYM. FOR PROTON transversity Interference fragmentation function ( not well known ) Proton Ks  p+ + p- r  p+ + p- Clear effect observed Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  19. COMPASS-HERMES COMPARISON in good agreement with the HERMES results Proton HERMES values scaled with 1/Dnn Global fit possible when interference fragmentation function measured (BELLE) Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  20. TRANSVERSE L POLARIZATION Transversity can be studied through transverse L polarization Transversity Polarized fragmentation function to L PT: target polarization; f : target dilution factor D(y): transverse spin transfer coefficient initial  struck quark, given by QED Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  21. TRANSVERSE L POLARIZATION L and L-bar on transversely polarized proton target two hadron events with the 2nd. vertex (v0) e, p, K rejection from p-track candidates by RICH Armenteros-Podolanski plot ( for V0 , after RICH selection) After RICH selection Polarization measured via parity violating decay Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  22. L POLARIZATION ON PROTON TARGET The measured polarizations are compatible with zero  small DTDL/q Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  23. TMD Effects Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  24. SIVERS EFFECTIN SIDIS Modulation wrt Sivers angle ± refer to the opposite orientation of the transverse spin of the nucleon Sivers angle: Azim. angle of a hadron wrt the nucleon spinFS=fh – fS nucleon spin struck quark spin Sivers PDF Scattering plane correlation between transverse momentum of the quark and the transverse polarization of the nucleon quark direction hadron （Breit frame） Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  25. SIVERS ASYMMETRIES h+ h− COMPASS proton 2007 Proton slightly positive for h+ PLB 692 (2010), 240 Deuteron compatible with zero PLB 673 (2009), 127 Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  26. SIVERS ASYMMETRIES FOR p & K Proton HERMES data show clear signals for p+ & K+ No definite conclusion with the COMPASS data due to limited statistics More statistics with 2010 COMPASS data + - Proton K+ K- Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  27. COMPARISON IN DETAIL COMPASS results smaller by a factor ~2 h+ COMPASS h+PLB 692(2010)240-246 HERMES p+PRL 103(2009)152002 COMPASS proton 2007 Possible explanation kinematical regions are different between COMASS and HERMES lower energy region probed in HERMES Inv. mass of the hadronic final state possible W dependence ? Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  28. Asymmeties for unpol. target Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  29. AZIMUTHAL ASYMMETRIES FOR UNPOL. TARGET TMD effects in SIDIS for unpolarized targets fh: azumuthal angle of hadron from scatt. plane coshand cos2 hmodulations affected by Cahn effect & Boer-Mulders Effect Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  30. CAHN EFFECT kinematical effect by transverse momentum of quark elementary cross-section: elementary Mandelstam variables: Taking account of transverse momentum of quark k: initial quark momentum kT: initial quark transverse momentum k’ : final quark momentum Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  31. BOER-MULDERS EFFECT Boer-Mulders function Correlation between quark transverse momentum and quark spin in unpolarized nucleon Contributes to cosh and cos2h moments with convoluted Collins function Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  32. COSfh MODULATION COMPASS 2004 6LiD large negative signals over all the x range strong dependence on z, PTh different for h+ & h- h+ Preliminary COMPASS 2004 6LiD h- Preliminary ( T- mode samples) Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  33. COS 2fh MODULATION COMPASS 2004 6LiD large signals at small-x strong dependence on z, x, PTh different for h+ & h- h+ Preliminary COMPASS 2004 6LiD h- Preliminary ( T- mode samples) Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  34. SUMMARY • COMPASS is a major player in the nucleon spin physics • Transverse Spin and TMD Effects have been intensively studied • Collins and Sivers asymmetries for  and K on • a transversely polarized proton and a deuteron target • two-hadron asymmetries • small transverse Λpolarization , compatible with zero • largeazimuthal asymmetries of hadrons produced on • an unpolarized deuteron target Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  35. BACKUP SLIDES Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  36. SIVERS ASYMMETRY FOR PROTON Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  37. SIVERS PDF GLOBAL FIT Global fit using AdSiv(±) and AdSiv(K±) from COMPASS and ApSiv(±) and ApSiv(K±) from HERMES: M. Boglione in collaboration with M. Anselmino, U. D’Alesio, A. Kotzinian, S. Melis, F. Murgia, A. Prokudin, C. Turk Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  38. SIVERS ASYM. DATA V.S. PREDICTION comparison with recent M. Anselmino et al. predictions arXiv:0805.2677 HERMES proton data COMPASS deuteron data marginal agreement with COMPASS proton data Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  39. TWO-HADRON ASYMMETRY - Deuteron- Deuteron Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

  40. TRANSVERSE MOMENTUM DEPENDENT PDFs Nucleon unpol. long. pol. trans. pol. number density Sivers unpol. Nucleon T-odd Parton helicity long. pol. Quark transversity Boer-Mulders survive after integration over kT trans. pol. T-odd Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

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