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Experimental Studies of Spin Duality

Experimental Studies of Spin Duality. P. Bosted (JLab). Jlab Users Meeting, June 2005. Bloom-Gilman duality in inclusive g 1 Factorization in polarized SIDIS Single-spin asymmetries in SIDIS. Bloom-Gilman Duality in g 1. UNPOLARIZED F 1 = 4/9 u(x) + 1/9 d(x) Sum s 1/2 + s 3/2.

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Experimental Studies of Spin Duality

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  1. Experimental Studies of Spin Duality P. Bosted (JLab) Jlab Users Meeting, June 2005 • Bloom-Gilman duality in inclusive g1 • Factorization in polarized SIDIS • Single-spin asymmetries in SIDIS

  2. Bloom-Gilman Duality in g1 UNPOLARIZED F1 = 4/9 u(x) + 1/9 d(x) Sum s1/2 + s3/2 POLARIZED g1 = 4/9 du(x) + 1/9 dd(x) Difference s1/2 - s3/2 • g1 more sensitive resonance structure • Expect duality “working” at higher Q2 than F1 P. Bosted, JLab Users Meeting, June 2005

  3. Hall B Experiment Eg1b Scattering of 1.6 and 5.7 GeV longitudinally polarized electrons off longitudinally polarized NH3, ND3 g1 determined from: Raw asymmetry Polarizations Dilution from N Model for R=sL/sT Model for A2 Model for F1 P. Bosted, JLab Users Meeting, June 2005

  4. CLASS PRELIMINARY CLAS Eg1b Results for g1 Q2=0.2 • Arrows (L to R) show W=1.7, 1.5, 1.2 GeV • Every 4th Q2 bin shown • Resonant structure clearly visible low Q2 • Gradually disappears at high Q2 • Data Q2>1 GeV2 oscillate around fit to high Q2 data proton deuteron Q2=0.4 Q2=0.8 Q2=1.7 Q2=2.5 P. Bosted, JLab Users Meeting, June 2005

  5. Integrals of g1 in Different W regions PROTON: CLAS PRELIMINARY • Integrate g1 for models, data in various W regions • Global duality for Q2>2 GeV2 • Local duality does not work as well (D(1234) low, S11(1535) high all Q2) M<W<2 DIS fit Q2=10 D(1234) GRSV TM, AAC TM 1.38<W<1.58 1.58<W<1.78 P. Bosted, JLab Users Meeting, June 2005

  6. Integrals of g1 in Different W regions DEUTERON: CLAS PRELIMINARY • Global duality for Q2>1.5 GeV2 • Adding elastic peak (open circles) helps • D(1234) still low all Q2 • 2nd and 3rd resonance region work amazingly well (isospin averaging) M<W<2 DIS fit Q2=10 D(1234) GRSV TM, AAC TM 1.38<W<1.58 1.58<W<1.78 P. Bosted, JLab Users Meeting, June 2005

  7. RSS Experiment in Hall C • Similar to Eg1, but fixed Q2=1.1 GeV2, W<1.9 GeV • Also measured g2: less model dependence for g1 • Both proton and deuteron (still under analsysis) • Good statistical accuracy P. Bosted, JLab Users Meeting, June 2005

  8. RSS Experiment in Hall C • On average, see agreement with PDF/TM models. • D(1234) low • 2nd and 3rd resonance regions high proton Q2=1.1 GeV2 See next talk for Hall A results on 3He P. Bosted, JLab Users Meeting, June 2005

  9. kT-dependentparton distributions Semi-Inclusive Deep Inelastic Scattering (SIDIS): • Probes orbital motion of quarks through quark transverse momentum distribution • Access to new PDFs not accessible in inclusive DIS. Off-diagonal PDFs vanish if quarks only in s-state! In addition T-odd PDFs require FSI (Brodsky et al., Collins, Ji et al. 2002) Mulders, This talk transversity Sivers This talk P. Bosted, JLab Users Meeting, June 2005

  10. SIDIS kinematic plane and relevant variables P. Bosted, JLab Users Meeting, June 2005

  11. Missing mass of pions in ep->e’pX p0 D++ p- p+ n D0 Duality question: is a cut on Mx (equivalent to z at low pt) needed for SIDIS factorization to work? Note absence of Delta in p0! P. Bosted, JLab Users Meeting, June 2005

  12. Determination of SIDIS g1/F1 (approximately A1) • Target polarization PT about 0.7 (0.3) for NH3 (ND3) • Beam polarization PB about 0.7 • Dilution factor f varies from 0.1 to 0.3: used Lund • model for n/p ratio (agrees with Hall C data) and • preliminary Hall B data for A-dependence • Depolarization factor DLL(y) evaluated assuming • R=sL/sT same as for inclusive. • Assumed Aperp=0 (not measured) • No radiative corrections applied • “p+” and “p-” include some K+, K- for P>1.5 GeV • p0 events cleanly identified with two photons P. Bosted, JLab Users Meeting, June 2005

  13. x-dependence of SIDIS proton g1/F1 W>2 GeV, Q2>1.1 GeV2, 0.4<z<0.7 • Good agreement with • HERMES p+ data at • higher W. • x-dependence follows PEPSI • (Lund) Monte Carlo using • GRSV polarized PDFs (LO) • Magnitude also in good • agreement with simulation P. Bosted, JLab Users Meeting, June 2005

  14. Polarized SIDIS: factorization tests Simple picture in valence region: sp(p+) = 4u(x)D+(z) + d(x)D-(z) sp(p-) = 4u(x)D-(z) + d(x)D+(z) dsp(p+) = 4du(x)D+(z) + dd(x)D-(z) dsp(p-) = 4du(x)D-(z) + dd(x)D+(z) (g1/F1)+-=[dsp(p+)+dsp(p-)]/[sp(p+)+sp(p-)] = [4du(x) + dd(x)] / [4u(x) + d(x)] = (g1/F1)inclusive Similarly for p0 (g1/F1)0=(g1/F1)inclusive (g1/F1)+- and (g1/F1)0 should be independent of z and pt, and equal to inclusive (g1/F1) P. Bosted, JLab Users Meeting, June 2005

  15. SIDIS: factorization studies GRVS Significant ? g1/F1 for inclusive, for the sum of p+ ,p-, and for p0 are fairly consistent with each other in the range 0.4<z<0.7, as expected in LO if factorization works. Cuts used: Mx>1.4 GeV, Q2>1.1 GeV2, W>2 GeV P. Bosted, JLab Users Meeting, June 2005

  16. z-dependence of SIDIS proton g1/F1 No significant z-dependence seen for p0 and p++ p- for 0.3<z<0.7, as expected if factorization holds Good agreement with PEPSI predictions including dropoff at high z for p-, due to increasing importance of dd(x)] CLAS 5.7 GeV PRELIMINARY P. Bosted, JLab Users Meeting, June 2005

  17. pt-dependence of SIDIS proton g1/F1 No pt dependence for p0 (green), as expected if factorization works p+ (red) and p- (blue) individually show pt dependence, but the sum of the two (not shown) is almost independent of pt, as expected if factorization works Reasonable agreement with PEPSI predictions. CLAS 5.7 GeV PRELIMINARY P. Bosted, JLab Users Meeting, June 2005

  18. Q2-dependence of SIDIS proton g1/F1 PRELIMINARY CLAS 5.7 GeV No Q2 dependence for Q2>1.1 GeV2. Evidence of HT for Q2<1.1 GeV2 W>2 GeV 0.4<z<0.7 P. Bosted, JLab Users Meeting, June 2005

  19. SIDIS g1/F1 for Deuteron CLAS 5.7 GeV PRELIMINARY Results don’t agree as well with PEPSI using GRSV, more sensitive to un-favored fragmentation function and NLO corrections than proton (although errors are about a factor of two larger) NLO QCD fits including new SIDIS CLAS data can help constrain polarized PDFs in valence region P. Bosted, JLab Users Meeting, June 2005

  20. Longitudinally Polarized Target SSA • Clear fdependence seen for proton target and p+, p0 • Fit A*sin(f) + B*sin(2f) for Twist-3 and Twist-2 respectively P. Bosted, JLab Users Meeting, June 2005

  21. SSA: x-dependence Twist-2 Higher Twist The hL functions depend on both x and pt, so no simple factorization tests aren’t possible. However, can check if (x,pt,z) dependence follows model expectations T P. Bosted, JLab Users Meeting, June 2005

  22. SSA: x-dependence Twist-2 Higher Twist Data in rough agreement with Efremov et al. predictions, except for p0 sin(f) term (evidence for terms not involving Collins fragmentation?) 5.7 GeV PRELIMINARY P. Bosted, JLab Users Meeting, June 2005

  23. SSA: PT-dependence of sinf moment ssinfLU(UL) ~FLU(UL)~ 1/Q (Twist-3) CLAS @4.3 GeV CLAS @5.7 GeV Beam and target SSA for p+ are consistent with increase with PT P. Bosted, JLab Users Meeting, June 2005

  24. Global duality seems to work for inclusive g1 for Q2>2 GeV2 for proton and Q2>1.5 for deuteron • Local duality does not seem to work for proton for any resonance region, but does seem to work for the deuteron for 2nd and 3rd resonance region • Factorization tests on polarized SIDIS data work surprisingly well for W>2 GeV, Q2>1.1 GeV2, 0.3<z<0.7, pt<1 GeV, even for Mx<2 GeV (another evidence of quark-hadron duality) • Breakdown of factorization at high z: may be due to Delta excitation or diffraction vector meson production (ongoing analysis) • Data may be used even with 6 GeV to study TMD PDFs, at least in limited kinematic region Summary

  25. QUESTIONS • Factorization W<2 GeV? • Factorization for kaons at low energy? • NLO treatment • TM corrections • Electroweak current? • … we’re just in the beginning! P. Bosted, JLab Users Meeting, June 2005

  26. Future: more p0 data in SIDIS advantages: • SIDIS p0 production is not contaminated by diffractive r • HT effects and exclusive p0 suppressed • Simple PID by p0-mass (no kaon contamination) • Provides complementary to p+/- information on PDFs disadvantages: reconstruction efficiency (requires detection of 2g) P. Bosted, JLab Users Meeting, June 2005

  27. 424 PbWO4 ……..crystals CLAS+Inner Calorimeter (IC) IC IC sE/E=0.0034/E+0.038/√E+0.022 CLAS+IC CLAS Reconstruction efficiency of high energy p0 with IC increases ~ 4 times due to small angle coverage CLAS IC at CLAS opens new avenue for studies of spin and azimuthal asymmetries of exclusive and semi-inclusiveg, p0,h,r+ P. Bosted, JLab Users Meeting, June 2005

  28. sUL ~ KM Longitudinally polarized target SSA using CLAS+IC 50 days of CLAS+IC curves, cQSM from Efremov et al Hunf=-5Hfav Hunf=-1.2Hfav Hunf=0 • Provide measurement of SSA for all 3 pions, extract the Mulders TMD and study Collins fragmentation with longitudinally polarized target • Allows also measurements of 2 pion asymmetries P. Bosted, JLab Users Meeting, June 2005

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