Presentation on theme: "Haiyan Gao Duke University Durham, NC, U.S.A."— Presentation transcript:
1Haiyan Gao Duke University Durham, NC, U.S.A. Semi-Inclusive DIS and Transverse-Momentum Dependent Parton Distribution Functions(SoLID CollaborationJune 13-14, 2012Haiyan GaoDuke UniversityDurham, NC, U.S.A.
2QCD Nucleon Structure Spin as an important knob Strong interaction, running coupling ~1-- QCD: the theory of strong interaction-- asymptotic freedom (2004 Nobel)perturbation calculation works athigh energy-- interaction significant atintermediate energyquark-gluon correlations-- confinementinteraction strong at low energycoherent hadron-- Chiral symmetry-- theoretical tools:pQCD, OPE, Lattice QCD, ChPTECharge and magnetism (current) distributionSpin distributionQuark momentum and flavor distributionPolarizabilitiesStrangeness contentThree-dimensional structureC. Carlson, H. Meyer, G. Orlandini, B. Pasquini,M. Schindler, L. Tiator, A.W. Thomas, H. WittigSpin as an important knob
3The Incomplete Nucleon: Spin Puzzle [X. Ji, 1997]DIS → DΣ 0.25RHIC + DIS → Dg« 1→ LqOrbital angular momentum of quarks and gluons is importantUnderstanding of spin-orbit correlations (atomic hydrogen, topological insulator…..)D. de Florian et al., PRL 101 (2008)
4Leading-Twist TMD PDFs Nucleon SpinQuark SpinQuark polarizationUnpolarized(U)Longitudinally Polarized (L)Transversely Polarized (T)Nucleon PolarizationULTh1 =Boer-Muldersf1 =h1L =Long-TransversityHelicityg1 =! relate g1, f1 -> collinear w/ pT dep.Say: Noval new information on structure of nucleon, spin-orbital cor and multi-parton cor.h1 =Transversityf 1T =Siversg1T =Trans-Helicityh1T =Pretzelosity
5Leading-Twist TMD PDFs Nucleon SpinQuark SpinQuark polarizationUnpolarized(U)Longitudinally Polarized (L)Transversely Polarized (T)Nucleon PolarizationULTh1 =Boer-Muldersf1 =h1L =Helicityg1 =Long-Transversity! relate g1, f1 -> collinear w/ pT dep.Say: Noval new information on structure of nucleon, spin-orbital cor and multi-parton cor.h1 =Transversityf 1T =Siversg1T =h1T =PretzelosityTrans-Helicity
6TMD PDFs: nucleon structure in 3-D momentum space TMD PDFs: nucleon structure in 3-D momentum space! Sivers as fixed x, Q2
8Access TMDs through Hard Processes protonleptonantileptonDrell-YanBNLJPARCFNALEICleptonpionprotonSIDISelectronpositronpione–e+ to pionsPartonic scattering amplitudeFragmentation amplitudeDistribution amplitude
9Access Parton Distributions through Semi-Inclusive DIS UnpolarizedBoer-MuldersTransversityPolarizedTargetSiversPretzelosityPolarizedBeam andTargetSL, ST: Target Polarization; e: Beam Polarization
10Example: Separation of Collins, Sivers and pretzelocity effects through angular dependence Collins frag. Func.from e+e- collisionsSIDIS SSAs depend on 4-D variables (x, Q2, z and PT )Large angular coverage and precision measurement of asymmetries in 4-D phase space is essential.
11Transversity The third PDFs in addition to f1 and g1L h1T =The third PDFs in addition to f and g1LLowest moment gives tensor chargeFundamental property, benchmark test of Lattice QCDA global fit to the HERMES p, COMPASS d and BELLE e+e- data by the Torino group, Anselmino et al.,arXiv:Solid red line : transversitydistribution, analysis atQ2=2.4 (GeV/c)2Solid blue line: Soffer bound|h1T| <= (f1+g1L)/2GRV98LO + GRSV98LODashed line: helicity distributiong1L, GRSV98LOTest bound violations
12Sivers Functionf 1T =Correlation between nucleon spin with quark orbital angular momentumImportant test for factorizationDifferent sign with twist-3 quark-gluon corr. dis. at high PT?T-odd final state interaction -> Target SSARecent developments in the evolution of Sivers function
13Older fit shows possibly discrepancy? Latest extraction based onHERMES p, COMPASS d and p data by M. Anselmino et al., arXiv: taking into account TMD evolution show consistency between the HERMES and COMPASS data
16Pretzlosity: h1T = Relativistic effect of quark PRD 78, 114024 (2008) (in models) direct measurement of OAM PRD 58, (1998) (more previous slide)Expect first non-zero Pretzelosityasymmetries
17E06-010: neutron A(U/L)T(π+K+, π-K-) First neutron data in SIDIS SSA&DSASimilar Q2 as HERMES experimentDisentangle Collins/Sivers effectsElectron beam: E = 5.9 GeVHigh luminosity L ~ 1036 cm-2s-140 cm transversely polarized 3He targetAverage beam current 12 uA (max: 15 uA as in proposal)BigBite at 30o as electron arm: Pe = 0.6 ~ 2.5 GeV/cHRSL at 16o as hadron arm: Ph = 2.35 GeV/cePolarized3He TargetpHRSL16og*e’BigBite30oThe experimental is configured as following. We have 5.9 GeV polarized electron beam incident on a 40 cm polarized 3He target.The scattered electron was detected by the BigBite spectrometer positioned 30 degrees to the beam right. And the momentum range is …The produced hardon was detected coincidently using the left high resolution spectrometer 16 degrees to the beam left. And the momentum setting is 2.35 GeV/c.This setup allowed us to measure the … asymmetries in the valence range …17
18Effective Polarized Neutron Target! 3He Target~90% ~1.5% ~8%SS’DEffective Polarized Neutron Target!Polarized 3He ran reliably throughout the experiment, and the following three experiments.Reached 55%-60% polarization with 15 mA beam and 20 minute spin flip! A NEW RECORD!
19Results on Neutron Sizable Collins π+ asymmetries at x=0.34? Sign of violation of Soffer’s inequality?Data are limited by stat. Needs more precise data!Negative Sivers π+ AsymmetryConsistent with HERMES/COMPASSIndependentdemonstration of negative d quark Sivers function.Model (fitting) uncertainties shown in blue band.Experimental systematic uncertainties: red bandX. Qian et al, Phys. Rev. Lett. 107, (2011)
20Double Spin Asymmetry: g1T Worm GearLeading twist TMD PDFsT-even, Chiral-evenDominated by real part of interference between L=0 (S) and L=1 (P) statesImaginary part -> Sivers effectFirst TMDs in Pioneer Lattice calculationarXiv: [hep-lat], Europhys.Lett.88:61001,2009arXiv: [hep-lat] , Phys.Rev.D83:094507,2011g1T =TOTg1T (1)S-P int.P-D int.Light-Cone CQM by B. PasquiniB.P., Cazzaniga, Boffi, PRD78, 2008g1T function is sometimes referred as the “worm-gear” function, since the spin direction for quark and nucleon are perpendicular to each otherIt is T-even anc Chiral-even.It is dominated by the real part of interference of quark wavefunctions that differ by one unit of quark OAM. Using a Light-cone constituent quark model, the g1T function can be explicitly decomposed to the major contribution of S-P states and a small contribution from the P-D interference.Effect resembles the g1T function has been recently studied using lattice QCD calculations. More studies are on-goingAnd it can be probed my measuring the beam-target double spin asymmetry, A_LT and look for the cos(…) modulationTargetSpinBeamHelicityee’πXn
21Existing ALT Results are preliminary No measurement until 2002Preliminary COMPASS resultsALT on proton and deuteronFixed beam helicity (μ beam)Low x, small predicted asymmetryPreliminary HERMES resultsALT on protonNew measurement neededDifferent target for flavor decompositionHigher precision at valence regionDouble spin reversal to cleanly separate ALTProtonarXiv: [hep-ex]PreliminaryThere is no measurement on ALT until COMPASS provided the first preliminary data on deuterons and protons using a Muon beam with fixed helicity.Very recently, HERMES collaboration also released their preliminary result on proton.A new measurement on neutron is needed for flavor decomposition, especially for the d quarkWe would like to focus on the valence region, where the models predict maximum signalAnd a double spin reversal can cleanly separate ALT from other SSA terms, including both beam-SSA and target-SSA.arXiv: [hep-ex]
22New Observable Reveals Interesting Behaviors of Quarks Huang, et. al. PRL. 108, (2012)Target:polarized 3He => polarized neutronFirst measurement of ALTbeam-target double-spin asymmetryFor JLab one-page highlight. Edited by Xiaodong Jiang 02/15/2012.E06010, Hall A Neutron Transversity experiment.Semi-inclusive deep inelastic scattering on a transversely polarized neutron (3He) target.Curves from theory models:WW-type: Wandzura-Wilczek, neglects higher-twist contributions, Kotzinian (2006).LCCQM: light-cone constituent quark model, Boffi (2009), Pasquini (2008).LCQDM: light-cone quark-diquark model, Zhu and Ma (2011).Indications:A non-vanishing quark “transversal helicity” distribution, reveals alignment of quark spin transverse to neutron spin directionQuark orbital motionsJ. Huang et al., PRL108, (2012)
23SoLID-Spin: SIDIS on 3He/Proton @ 11 GeV E : Single Spin Asymmetry on Transverse 90 days, rating A E : Single and Double Spin Asymmetry on 35 days, rating A PR : Single and Double Spin Asymmetries on Transverse Proton (conditionally approved)International collaboration with 180Collaborators from 8 countriesWhite paperKey of SoLID-Spin program:Large Acceptance + High Luminosity 4-D mapping of asymmetries Tensor charge, TMDs …Lattice QCD, QCD Dynamics, Models.
243-D neutron π+/π- Collins/Sivers Asymmetries at Q2=2.0 GeV2 Collins/Sivers asymmetries vs. x and transverse momentum PT at different z at fixed Q2.Multi-dimensional nature.Targets: proton and neutronDetect: positive pion and negative pions!Torino 2008
25Projected Data (E12-10-006) X. Qian et al in PRL 107, 072003 Total 1400 bins in x, Q2, PT and z for 11/8.8 GeV beam.z ranges from 0.3 ~ 0.7, only one z and Q2 bin of 11/8.8 GeV is shown here.π+ projections are shown, similar to the π- .X. Qian et al in PRL 107,
27SoLID Data Projection for ALT (Partial) E and E : Neutron ALT Projection of one out of 48 Q2-z bins for π-Center of points:Scale for error bars:E Data Huang, et. al. PRL 108 (2012)! Sign! Will be improved
28E12-11-007 Projection/AUL (Partial) Projection of a single Q2-z bin for π+Center of points:+ boundScale for error bars:
29PAC38: Conditionally approved, update submitted to PAC39 Proposal PR : Target Single Spin Asymmetry in SIDIS (e, eπ± ) Reaction on a Transversely Polarized Proton Target and SoLIDMeasure SSA in SIDIS using transversely polarized proton targetUse similar detector setup as that of two approved 3He SoLID expts.Use JLab/UVa polarized NH3 target with upgraded design of the magnetTarget spin-flip every two hours with average in-beam polarization of 70%Two Beam energies: 11 GeV and 8.8 GeVPolarized luminosity with 100nA current: 1035 cm-2s-1Beamline chicane to transport beam through 5T target magnetic field (already designed for g2p expt.)NH3targetSpokespersons: K. Allada (Jlab), J. P. Chen (Jlab), Haiyan Gao (Contact), Xiaomei Li (CIAE), Z-E. Meziani (Temple)PAC38: Conditionally approved, update submitted to PAC39
31Projected measurements in 1-D (x) Expected improvement of Sivers function(A. Prokudin)xAssumption: We know the kT dependence, Q2 evolution of TMDs.Also knowledge on TMFF project onto 1-D in x to illustrate the power of SoLID-3He.
32SummaryFrontiers in nucleon structure go beyond collinear, 1-D pictureTMDsThree-dimensional description of nucleon in momentum spaceDirect link with orbital motion (orbital angular momentum)Transverse motion: spin-orbit correlations, multi-parton correlations, dynamics of confinement and QCD10% quark tensor charge from both SSA data from SoLID provides excellent test of LQCD predictionsJLab 12-GeV upgrade will provide excellent opportunities to map out the 3-dimensional structure of the nucleon through TMDs and GPDsSoLID will just do that!Thanks to B. Pasquini, J. P. Chen, J. Huang, and X. Qian and others in the SoLID collaborationSupported in part by U.S. Department of Energy under contract number DE-FG02-03ER41231