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Single and Double Spin Asymmetry Measurements in Semi-Inclusive DIS on Polarized 3 He

Single and Double Spin Asymmetry Measurements in Semi-Inclusive DIS on Polarized 3 He. Vincent Sulkosky Massachusetts Institute of Technology XX International Workshop on Deep-Inelastic Scattering and Related Subjects 28 March 2012, University of Bonn, Germany.

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Single and Double Spin Asymmetry Measurements in Semi-Inclusive DIS on Polarized 3 He

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  1. Single and Double Spin Asymmetry Measurements in Semi-Inclusive DIS on Polarized 3He Vincent Sulkosky Massachusetts Institute of Technology XX International Workshop on Deep-Inelastic Scattering and Related Subjects 28 March 2012, University of Bonn, Germany

  2. Transverse Momentum Dependent(TMD) Parton Distributions • TMD PDFs link • Intrinsic motion of partons • Parton spin • Spin of the nucleon • Multi-Dimension structure • Probes orbital motion of quarks • A new phase of study, fast developing field • Great advancement in theories (factorization, models, Lattice ...) • Not systematically studied until recent years • Semi-Inclusive DIS (SIDIS): HERMES, COMPASS, Jlab-6GeV, ... • p-p(p_bar) process : FNAL, BNL, ...

  3. Nucleon Spin Quark Spin Leading-Twist TMD PDFs h1= Boer-Mulders f1 = h1L= Worm Gear (Kotzinian-Mulders) Helicity g1 = h1= Transversity f1T= g1T= h1T= Sivers Worm Gear Pretzelosity : Survive trans. Momentum integration

  4. Nucleon Spin Quark Spin Leading-Twist TMD PDFs h1= Boer-Mulders f1 = h1L= Worm Gear (Kotzinian-Mulders) Helicity g1 = h1= Transversity f1T= g1T= h1T= Sivers Worm Gear Pretzelosity : Probed by E06-010

  5. Transversity • Characteristics of Transversity • h1T = g1Lfor non-relativistic quarks • No gluon Transversityin nucleon • Chiral-odd → difficult to access in inclusive DIS • Soffer’s bound |h1T| <= (f1+g1L)/2 • Tensor Charge: • Integration of Transversityover x. • An important quantity of nucleon. • Calculable in LQCD q q Helicity state N N

  6. Sivers Function • Left-right asymmetric quark distribution in a transversely polarized nucleon • Related to the angular momentum of quarks Lq • Final state interactions (FSI) can lead to non-zero asymmetries • (Brodsky, Hwang, Schmidt, 2002) • Imaginary part of interference • Lq=0 ✖Lq=1 quark wave functions. • Gauge invariance of QCD requires Sivers • function to flip sign between semi-inclusive • DIS and Drell-Yan:

  7. “Worm-Gear” Functions g1T • Leading twist TMD PDFs • T-even, Chiral-even • Dominated by real part ofinterference between L=0 (S) and L=1 (P) states • Imaginary part -> Sivers effect • No GPD correspondence • a genuine sign of intrinsic transverse motion • First TMDs in Pioneer Lattice calculation • arXiv:0908.1283 [hep-lat], arXiv:1011.1213 [hep-lat] Worm Gear g1T (1) S-P int. TOT g1T= P-D int. Light-Cone CQM by B. Pasquini B.P., Cazzaniga, Boffi, PRD78, 2008

  8. Access TMDs through SIDIS • Detect one hadron from fragmentation of the struck quark in coincidence with the scattered electron • Flavor tagging possible through fragmentation function • z = Eh/ν at least > 0.2

  9. Access TMDs through SIDIS Unpolarized Boer-Mulder Polarized Target Transversity/Collins Sivers Pretzelosity Polarized Beam and Target Worm Gear SL, ST: Target Polarization; e: Beam Polarization

  10. Separation of TMDs Separate different effects through angular dependence • Collins asymmetry: • Sivers asymmetry: • “Pretzelosity”: • Double-spin asymmetry:

  11. Jefferson Lab CEBAF C A B

  12. CEBAF: Continuous Electron Beam Accelerator Facility Properties Emax6.0 GeV Imax200mA Pe85% Beam To 3 Halls Re-circulating arcs accelerating structures CHL RF separators

  13. E06‑010 Experiment Setup Luminosity Monitor • Successful data taking 2008-09 • Polarized electron beam • ~80% polarization • Fast Flipping of helicity at 30Hz (for g1T) • Charge asymmetry: controlled by online feed back at PPM level • Polarized 3He target • BigBite at 30º as electron arm • Dipole magnet,Pe = 0.7 ~ 2.2 GeV/c • MWDC/shower-preshow/scintillator • HRSL at 16º as hadron arm • QQDQ config, Ph = 2.35 GeV/c • Scintillator/drift chambers/Cherenkov/RICH/ lead glass Beam Polarimetry (Møller + Compton)

  14. Angular Coveragecolor coded for each target spin direction: up, down, left and right. Collins: Sivers and Worm-Gear: Target spin orientations: up-downand left-right (increases angular coverage)

  15. HRS and BigBite Spectrometers

  16. Particle Identification Electron Identification from BigBite Hadron Identification from HRS • Kaonand proton data can be separated by coincidence/TOF and the RICH detector: both provide K/π ~ 4σ separation • Combined pion rejection 99.9%

  17. Polarized 3He Target • Effectively a polarized neutron target • Improved figure of merit • Rb+K hybrid mixture cell • Narrow bandwidth lasers • Compact size: No cryogenic support needed ~90% ~1.5% ~8% 3He Cell Beam

  18. Performance of 3He Target • High luminosity: L(n) = 1036 cm-2 s-1 • Record high steady~ 60% polarization with 15 A beam with automatic spin flip every 20 minutes History of Figure of Merit of Polarized 3He Target Average 3He pol. = 55%

  19. SSA check: HRS single-arm3He SSA(Witness channels on 3He, not corrected for target polarization and dilution) K. Allada Univ. of Kentucky 2010. False asymmetry < 0.1%

  20. 3He Target Single-Spin Asymmetry in SIDIS Phys. Rev. Lett. 107 (2011) 072003 ~87% ~8% ~1.5% 3He Collins SSA are not large (as expected). 3He Sivers SSA: negative sign for π+, consistent with zero for π- After correction of N2 dilution (dedicated reference cell data) Blue band: model (fitting) uncertainties Red band: other systematic uncertainties

  21. Results on Neutron Phys. Rev. Lett. 107 (2011) 072003 Collins asymmetries are not large, except at x=0.34 Sivers agree with global fit, and light-cone quark model. Consistent with HERMES/COMPASS favors negative • Independent demonstration of negative d-quark Sivers function. Blue band: model (fitting) uncertainties Red band: other systematic uncertainties Radiative correction: bin migration + uncer. of asy. Spin-dependent FSI estimated <1% (Glauberrescattering + no correction) Diffractive rho: 3-10%

  22. 3He ALT(DSA) Results • First measurement with 3He target • 30 Hz beam helicity flips • Two independent analysis teams; cross checks • Corrected for small component of long. target spin, SL • Data suggest non-zero SIDIS ALT: π-, +2.8σ (sum all bins) g* Phys. Rev. Lett. 108 (2012) 052001 BigBite ~7o 30o arXiv:1108.0489 [nucl-ex] h+/- e’ ST 3He Spin PT Higher twist contribution NOT included SL +Global A1 e

  23. Neutron ALT Extraction • Corrected for proton dilution, fp • Predicted proton asymmetry contribution < 1.5% (π+), 0.6% (π-) • , sensitive to d quark • Dominated by L=0 (S) and L=1 (P) interference • Consist w/ model in signs, suggest larger asymmetry Phys. Rev. Lett. 108 (2012) 052001

  24. Summary • First measurement of Collins and Sivers moments (AUT) on 3He • AUT results on neutron: • Collins:π+are π- asymmetries consistent with zero except at x ~ 0.34 for π+ • Sivers:π- is consistent with zero; however, π+favor negative values • First indication of a non-zero ALT: 3He→π-, +2.8σALT(sum all bins), which suggests non-zero g1T • Preliminary Kaon±Sivers and Collins moments are also available • The neutron results combined with existing proton and deuteron data will aid in constraining Transversity and Sivers PDFs using global fits • JLab-12 GeV: Precision DSA and SSA measurements in SIDIS will be one of the highlights as discussed inK. Allada’spresentation in Future of DISsession (27th March @ 17:20).

  25. Jefferson Lab E06-010 Collaboration Institutions CMU, Cal-State LA, Duke, Florida International, Hampton, UIUC, JLab, Kharkov, Kentucky, Kent State, Kyungpook National South Korea, LANL, Lanzhou Univ. China, Longwood Univ. Umass, Mississippi State, MIT, UNH, ODU, Rutgers, Syracuse, Temple, UVa, William & Mary, Univ. Sciences & Tech China, Inst. of Atomic Energy China, Seoul National South Korea, Glasgow, INFN Roma and Univ. Bari Italy, Univ. Blaise Pascal France, Univ. of Ljubljana Slovenia, Yerevan Physics Institute Armenia. Collaboration members K. Allada, K. Aniol, J.R.M. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, P.C. Bradshaw, P. Bosted, A. Camsonne, M. Canan, G.D. Cates, C. Chen, J.-P. Chen (Co-SP), W. Chen, K. Chirapatpimol, E. Chudakov, , E. Cisbani(Co-SP), J. C. Cornejo, F. Cusanno, M. Dalton, W. Deconinck, C. de Jager, R. De Leo, X. Deng, A. Deur, H. Ding, C. Dutta, D. Dutta, L. El Fassi, S. Frullani, H. Gao(Co-SP), F. Garibaldi, D. Gaskell, S. Gilad, R. Gilman, O. Glamazdin, S. Golge, L. Guo, D. Hamilton, O. Hansen, D.W. Higinbotham, T. Holmstrom, J. Huang, M. Huang, H. Ibrahim, M. Iodice, X. Jiang (Co-SP), G. Jin, M. Jones, J. Katich, A. Kelleher, A. Kolarkar, W. Korsch, J.J. LeRose, X. Li, Y. Li, R. Lindgren, N. Liyanage, E. Long, H.-J. Lu, D.J. Margaziotis, P. Markowitz, S. Marrone, D. McNulty, Z.-E. Meziani, R. Michaels, B. Moffit, C. Munoz Camacho, S. Nanda, A. Narayan, V. Nelyubin, B. Norum, Y. Oh, M. Osipenko, D. Parno, J. C. Peng(Co-SP), S. K. Phillips, M. Posik, A. Puckett, X. Qian, Y. Qiang, A. Rakhman, R. Ransome, S. Riordan, A. Saha, B. Sawatzky,E. Schulte, A. Shahinyan, M. Shabestari, S. Sirca, S. Stepanyan, R. Subedi, V. Sulkosky, L.-G. Tang, A. Tobias, G.M. Urciuoli, I. Vilardi, K. Wang, Y. Wang, B. Wojtsekhowski, X. Yan, H. Yao, Y. Ye, Z. Ye, L. Yuan, X. Zhan, Y. Zhang, Y.-W. Zhang, B. Zhao, X. Zheng, L. Zhu, X. Zhu, X. Zong.

  26. Backup Slides

  27. Experimental Extraction of g1T • Extractable fromDouble Beam-Target Spin Asymmetry (DSA) in SIDIS with transversely polarized target: ALT Scattering Plane n e’ e X π Beam Helicity Target Spin

  28. COMPASS Proton Existing ALT Results arXiv:1012.0155 [hep-ex] • COMPASS • Last Session, C. Schill • Proton , Deuteron • HERMES • Last Session, L. Pappalardo • Jlab E06-010 • This talk • Pol. 3He Target (eff. pol. n) • Fast beam helicity flips Deuteron Eur. Phys. J. Special Topics 162, 89–96 (2008)

  29. x bin 1 2 3 4 Kinematic Coverage Q2>1GeV2 <Q2> ~ 2.0 GeV2 <W> ~ 2.8 GeV <z> ~ 0.5 W>2.3GeV z=0.4~0.6 W’>1.6GeV

  30. Transversity Data Analysis Flow Raw Data Run data base Spectrometer optics Detector calibration Scalers Target polarization Farm Production PID cuts Reconstruction Cuts Beam Cuts Lumi Cuts … Event Selection Two independent teams: Blue vs Red. Witness Asymmetry Corrections: luminosity, DAQ deadtime, detector efficiency, …. Coincidence Asymmetry N2 Dilution correction Background Separation of Collins vsSivers 3He to neutron correction Physics Analysis

  31. Hadron Particle Identification Aerogel Cherenkov: separates pions and other hadrons Gas Cherenkov and lead glass: separate hadrons from electrons • Kaonand proton data can be cleaned up by coincidence/TOF and the RICH detector: both provide K/π ~ 4σ separation • Combined pion rejection 99.9%

  32. Particle Identification for Kaons

  33. Analysis: Target Single-Spin Asymmetry Target single-spin asymmetry from normalized yields, need to consider : beam charge, target density, DAQ life time, detector efficiency etc. 2845 target spin “local pairs” Automatic target spin flip once every 20 minutes. Beam Charge + vs Beam Charge - Beam charges are well-balanced between the pairs

  34. Analysis of Asymmetry • Two teams carried out independent analysis • Red Team: Maximum Likelihood Method • Blue Team: Local Pair-Angular Bin-Fit Method • Do not share any code. • Many cross checks on intermediate results.

  35. Two team independent asymmetry analyses Many cross checks on intermediate asymmetries. Red team. Blue team. Blue team implemented Red team’s method.

  36. Correction for N2 Dilution Cross section ratios determined through reference cell N2 and 3He data.

  37. From 3He to Neutron very small (< 0.003) Cross section ratios determined through reference cell H2 and 3He data.

  38. MLE vs Local Spin Pair Methods DSA Consistency Checks

  39. SIMC: E06-010 Monte Carlo Test bias and efficiency of MLE method at E06-010 statistics Successful asymmetry extraction from simulated data

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