3 Transversity Three twist-2 quark distributions: Momentum distributions: q(x,Q2) = q↑(x) + q↓(x)Longitudinal spin distributions: Δq(x,Q2) = q↑(x) - q↓(x)Transversity distributions: δq(x,Q2) = q┴(x) - q┬(x)Some characteristics of transversity:δq(x) = Δq(x) for non-relativistic quarksδq and gluons do not mix → Q2-evolution for δq and Δq are differentChiral-odd → not accessible in inclusive DISIt takes two chiral-odd objects to measure transversitySemi-inclusive DISChiral-odd distributions function (transversity)Chiral-odd fragmentation function (Collins function)
4 Leading-Twist Quark Distributions ( A total of eight distributions)No K┴ dependenceK┴ - dependent, T-evenK┴ - dependent, T-odd
5 Eight Quark Distributions Probed in SIDIS UnpolarizedTransversityPolarized targetSiversPolarzied beam and targetSL and ST: Target Polarizations; λe: Beam Polarization
6 AUTsin() from transv. pol. H target Simultaneous fit to sin( + s) and sin( - s)`Collins‘ moments`Sivers‘ momentsNon-zero Collins asymmetryAssume dq(x) from model, thenH1_unfav ~ -H1_favNeed independent H1 (BELLE)Sivers function nonzero (p+)orbital angular momentum of quarksRegular flagmentation functions
7 Collins asymmetry from COMPASS Transversely polarized 6LiD targetCover smaller xConsistent with 0hep-ex/COMPASS data:~ factor of 12 in statistics
8 Current Status Collins Asymmetries - sizable for proton large at high xlarge for p-- consistent with 0 for deuteron- cancellation between p and n?Sivers Asymmetries- non-zero for p+ from proton- consistent with zero all other channels.Fit by Anselmino et al. and other groupsData on neutron at high x complementary and very helpful
13 SIDIS at JLab Extensive SIDIS program with 12 GeV upgrade Starting with 6 GeV running with optimized kinematicsHigh luminosity compensates low rate at larger scattering angle to reach large Q2Comparable Q2 range as HERMESAccess high x regionFactorization?experimental tests.
14 Preliminary results of factorization test from JLab for semi-inclusive pion production Hall-C E00-108CLAS 5.7GeV dataData are well described by calculations assuming factorizationSimilar z-dependence for different x-binsRecent theory work on SIDIS factorization (hep-ph )
15 Planned neutron transversity experiment at JLab
16 JLab Hall-A E03-004 Experiment Single Target-Spin Asymmetry in Semi-Inclusive p Electroproduction on a Transversely Polarized 3He TargetArgonne, CalState-LA, Duke, E. Kentucky, FIU, UIUC, JLab, Kentucky, Maryland, UMass, MIT, ODU, Rutgers, Temple, UVa, W&M, USTC-China, CIAE-China, Glasgow-UK, INFN-Italy, U. Ljubljana-Slovenia, St. Mary’s-Canada, Tel Aviv-Israel, St. Petersburg-RussiaSpokespersons: J.-P. Chen (JLab), X. Jiang (Rutgers), J. C. Peng (UIUC)High luminosity (1036 s-1)15 μA electron beam on 10-atm 40-cm 3He targetMeasure neutron transversitySensitive to δd, complementary to HERMESDisentangle Collins/Sivers effectsProbe other K┴-dependent distribution functions
17 Jefferson Lab Hall A Experimental Setup for polarized n (3He) Experiments BigBite
23 Disentangling Collins and Sivers Effects Collins angle: ФC=Фhl + ФSlSivers angle: ФS=Фhl - ФSlCoverage in ФSl is increased by rotating target polarization
24 Model Predictions for δq and AUT Quark – diquark model (solid) and pQCD-based model (dashed)B. –Q. Ma, I. Schmidt and J. –J. Yang, PRD 65, (2002)AUT for favored quark fragmentation (dashed) and favored + unfavored (solid) at Q2 = 2.5 GeV2 and integrated over zAUT is large, increasing with xAUTπ+(p): dominated by δuAUTπ-(n): both δu and δd contribute
25 Expected Statistical Sensitivities Comparison with HERMES projection
26 Expected Statistical Sensitivities HERMESph(e,e’p)JLab E Projection3Heh(e,e’p-)
27 Status and Schedule Polarized 3He: need to add a set of vertical coils fast polarization flip is being testedBigBite spectrometerused in SRC experimentnew detectors will be used for GEn experimentHSR is ready, excellent PIDp- part is approved and scheduled to run in fall of 2007p+ proposal is being developedK+/- got for free
30 g2: twist-3, q-g correlations experiments: transversely polarized targetSLAC E155x, JLab Hall Ag2 leading twist related to g1 by Wandzura-Wilczek relationg2 - g2WW: a clean way to access twist-3 contribution(q-g correlations)h1 term suppressed by quark mass
31 Precision Measurement of g2n(x,Q2): Search for Higher Twist Effects Jefferson Lab Hall A E97-103Precision Measurement of g2n(x,Q2): Search for Higher Twist EffectsT. Averett, W. Korsch (spokespersons) K. Kramer (Ph.D. student)Improve g2n precision by an order of magnitude.Measure higher twist quark-gluon correlations.Accepted by PRL, K. Kramer et al., nucl-ex/
32 E results: g2n vs. Q2measured g2n consistently higher than g2ww: positive twist-3higher twist effects significant below Q2=1 GeV2Models (color curves) predict small or negative twist-3
36 Other SIDIS experiments Sea asymmetrySpin-flavor decomposition
37 Projected sensitivity for A Hall-A proposal PRSemi-inclusive pion and kaon production using Bigbite and HRS spectrometersProjected sensitivity for
38 Large acceptance BETA detector and the HMS spectrometer A Hall-C proposal PRLarge acceptance BETA detector and the HMS spectrometer
39 Other planned experiments and outlook Approved SIDIS proposal in Hall B (H. Avakian)A new proposal with polarized 3He (n) for spin-flavor decomposition.Other measurements under consideration.SIDIS with JLab 12 GeV upgrade:TransversityTransverse momentum dependent parton distributionsSpin-flavor decompositionSea asymmetry
40 SummaryWith high luminosity and moderate energy, factorization seems reasonable for JLab SIDIS.JLab experiment E will measure neutron SSA using transversely polarized 3He target.Experimental preparation underwaydata taking in fall 2007.Other transverse spin experiments.Other SIDIS experiments at JLab and 12 GeV.
42 Collins Effect at 12 GeV Upgrade clas12Collins Effect at 12 GeV UpgradesUT ~CollinsFrom H. AvakianStudy the Collins fragmentation for all 3 pions with a transversely polarized target and measure the transversity distribution function. JLAB12 cover the valence region.
43 Kaon fragmentation functions KKP global fit:This implies:Connections between the parton distribution and fragmentation functions?
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