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Neutron Transversity

Neutron Transversity. Vincent Sulkosky Massachusetts Institute of Technology 2011 JLab Users Group Meeting June 8 th , 2011. Transverse Momentum Dependent (TMD) Parton Distributions. in DIS Nucleon -> Pancake. TMD PDFs link Intrinsic motion of partons Parton spin

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Neutron Transversity

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  1. NeutronTransversity Vincent Sulkosky Massachusetts Institute of Technology 2011 JLab Users Group Meeting June 8th, 2011

  2. Transverse Momentum Dependent(TMD) Parton Distributions in DIS Nucleon -> Pancake • 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, ... L ≠? 0 →Transverse motion Additional details in X. Qian’s and A. Metz’s talks on June 7th.

  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 transversity in nucleon • Chiral-odd → difficult to access in inclusive DIS • Soffer’s bound |h1T| <= (f1+g1L)/2 • Tensor Charge: • Integration of transversity over 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. E06‑010 Experiment Setup Luminosity Monitor • Success full data taking 2008-09 • Polarized electron beam • ~80% polarization • Fast Flipping at 30Hz • 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 chamber/Cherenkov/RICH/ lead glass Beam Polarimetry (Møller + Compton)

  12. 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

  13. 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)

  14. HRS and BigBite Spectrometers

  15. Particle Identification Hadron Identification from HRS Electron Identification from BigBite

  16. 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%

  17. Particle Identification for Kaons

  18. 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

  19. 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%

  20. 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

  21. 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%

  22. 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.

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

  24. 3He Target Single-Spin Asymmetry in SIDIS ~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

  25. Results on Neutron 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%

  26. Paper on the arXiv • arXiv: 1106.0363, will submit in a few days.

  27. 3He ALT(DSA) Results Ph.D. thesis of J. Huang (MIT 2011). • 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* BigBite ~7o 30o Preliminary h+/- e’ ST 3He Spin Higher twist contribution NOT included PT SL +Global A1 e

  28. 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 Preliminary

  29. Summary • “Neutron Transversity” experiment (E06-010) completed. • 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 • Results to be submitted to PRL very soon • First indication of a non-zero ALT: 3He→π-, +2.8σALT(sum all bins) • Preliminary Kaon±Sivers and Collins moments are also available • The neutron results combined with existing proton and deuteron data will aid in constraining the d-quark sivers function • JLab-12 GeV: Precision SSA measurements in SIDIS will be one of the highlights as discussed inX. Qian’s thesis prize presentation.

  30. 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.

  31. Backup Slides

  32. 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

  33. 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)

  34. 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

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

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

  37. MLE vs Local Spin Pair Methods DSA Consistency Checks

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