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 Circum-Pan-Pacific Symposium on High Energy Spin Physics, Cairns, Australia, June 20-24 , 2011

OUTLINE The experimental setup Data taking history 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 Takahiro Iwata

ＣＯＭＰＡＳＳ ａｔ CERN Lake LEMAN LH C Airport SPS (p:450GeV) CERN (France) N Nucleon Structure Hadron Spectroscopy LH C COMPASS Airport SPS (p:450GeV) CERN (France) N CERN (Suisse) 21/11/2018 BEACH08 26 june 2008 3 Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 Takahiro Iwata

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 SM1 0.003 < x < 0.5 10-3 < Q2 < 10 GeV2 Polarised Target MuonWall 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 Takahiro Iwata

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 Takahiro Iwata

THE RICH DETECTOR radiator gas: C4F10 mirror wall: 20 m2 surface photon detectors 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 Takahiro Iwata

DATA TAKING HISTORY 2002 - 2011 2002 Data taking started muon program with 160 GeV polarized muon 2002-2006 6LiD polarized target ( pol. deuterons) L-mode: 80 / T-mode: 20 , DG/G measurement 2005 no data taking 2007 NH3 polarized target (pol. protons) L-mode: 50 /T-mode: 50 2008, 2009 hadron program with 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 Takahiro Iwata

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

TRANSVERSE SPIN &TMD EFFECTS IN COMPASS Transversity PDF quark with spin parallel to the nucleon spin in a transversely polarized nucleon DTq(x) = q↑↑(x) - q↑↓(x) 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 Takahiro Iwata

Transverse Spin Effects Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 Takahiro Iwata

SINGLE HADRON ASYMMETRIES IN SIDIS SIDIS cross-section for transv. PT Collins Sivers 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 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 quark direction hadron （Breit frame） Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 Takahiro Iwata

COLLINS ASYMMETRY Collins Asymmetry Modulation wrt the Collins angle ± : opposite orientation of the transverse spin of the nucleon PT is the target polarization; DNN is 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 Takahiro Iwata

COLLINS ASYMMETRIES h+ h− h+ h− proton deuteron 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 Takahiro Iwata

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

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

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 Takahiro Iwata

TWO-HADRON ASYMMETRY Two hadrons produced in SIDIS Modulation wrt the angle between two-hadron plane and struck quark spin i f h l-l’ f : target dilution facto PT : target polarization DNN : transverse spin transfer coefficient initial  struck quark Two-hadron asymmetry 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 Takahiro Iwata

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 Takahiro Iwata

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 Takahiro Iwata

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 Takahiro Iwata

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 Takahiro Iwata

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 Takahiro Iwata

TMD Effects Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 Takahiro Iwata

SIVERS EFFECT IN 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 spin FS= 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 Takahiro Iwata

SIVERS ASYMMETRIES h+ h− slightly positive for h+ compatible with zero 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 Takahiro Iwata

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 + - Proton K+ K- Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 Takahiro Iwata

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

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

AZIMUTHAL ASYMMETRIES FOR UNPOL. TARGET TMD effects in SIDIS for unpolarized targets fh : azumuthal angle of hadron from scatt. plane cos h and cos 2 h modulations affected by Cahn effect & Boer-Mulders Effect Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 Takahiro Iwata

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 Takahiro Iwata

BOER-MULDERS EFFECT Boer-Mulders function Correlation between quark transverse momentum and quark spin in unpolarized nucleon Contributes to cos h and cos 2h moments with convoluted Collins function Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 Takahiro Iwata

strong dependence on z, PTh COSf h 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 Takahiro Iwata

strong dependence on z, x, PTh COS 2f h 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 Takahiro Iwata

COMPASS is a major player in the nucleon spin physics 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 Λ polarization , compatible with zero large azimuthal asymmetries of hadrons produced on an unpolarized deuteron target Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 Takahiro Iwata

Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011 BACKUP SLIDES Takahiro Iwata Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011

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

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 Takahiro Iwata

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 Takahiro Iwata

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

TRANSVERSE MOMENTUM DEPENDENT PDFs Nucleon unpol. long. pol. trans. pol. number density Sivers unpol. Nucleon Parton T-odd helicity long. pol. RICH + AGS annual Users’ Meeting June 6, 2006, www.bnl.gov/rhic ags/users meetings/workshops/basp , and paper in preparation. Quark transversity Boer-Mulders survive after integration over kT trans. pol. T-odd Takahiro Iwata Circum-Pan-Pacific Symposium, Cairns, Australia, June 20-24 , 2011