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Studies of spin-orbit correlations. H.Avakian (JLab). Transverse Spin Phenomena and Their Impact on QCD a Workshop in Honor of Gary Goldstein's 70th Birthday October 28-29, 2010 Thomas Jefferson National Accelerator Facility. Outline.

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## Studies of spin-orbit correlations

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**Studies of spin-orbit correlations**H.Avakian (JLab) Transverse Spin Phenomena and Their Impact on QCD a Workshop in Honor of Gary Goldstein's 70th BirthdayOctober 28-29, 2010Thomas Jefferson National Accelerator Facility H.Avakian, JLab, Oct 29**Outline**Transverse structure of the nucleon and partonic correlations Physics motivation kT-effects in double spin asymmetries Physics with transversely polarized hadrons and quarks kT-effects and SSA in pion production Higher twist effects Kaon puzzle Future studies of 3D PDFs at CLAS at 6 GeV Transverse structure & CLAS12 Summary H.Avakian, JLab, Oct 29**SIDIS kinematical plane and observables**Target polarization Cross section is a function of scale variables x,y,z U unpolarized L long.polarized T trans.polarized z Beam polarization sin2f moment of the cross section for unpolarized beam and long. polarized target 3 H.Avakian, JLab, Oct 29**Structure of the Nucleon**TMD PDFs q(x,kT), Dq(x,kT)… GPD/IPDs H(x,rT), H~(x,rT)… Wpu(k,rT) “Mother” distributions (Wigner, GTMDs,..) d2rT d2kT d2kT d2rT PDFsq(x), Dq(x)… 4 H.Avakian, JLab, Oct 29**DIS vs SIDIS → additional hadron detection.**H.Avakian, JLab, Oct 29**Acceptances and efficiencies**HERMES How acceptance in f and PT affect the A1 and Ds extractions in SIDIS? H.Avakian, JLab, Oct 29**Quark distributions vs kT: and b**B.Musch arXiv:0907.2381 B.Pasquini et al B.Musch arXiv:0907.2381 Higher probability to find at large kT u-quarks anti-aligned with proton spin and d-quarks 7 7 H.Avakian, JLab, Oct 29**CLAS configurations**ep→e’pX Inner Calorimeter e p- p+ Unpolarized and longitudinally polarized targets Unpolarized, longitudinally and transversely polarized targets • Polarized NH3/ND3 (no IC, ~5 days) • Unpolarized H (with IC ~ 60 days) • Polarized NH3/ND3 with IC 60 days • 10% of data on carbon • Polarized HD-Ice (no IC, 25 days) • Polarizations: • Beam: ~80% • NH3 proton 80%,ND3 ~30% • HD (H-75%,D-25%) 8 H.Avakian, JLab, Oct 29**2**SIDIS with JLab at 6 GeV Scattering of 5.7 GeV electrons off polarized proton and deuteron targets • DIS kinematics, Q2>1 GeV2, W2>4 GeV2, y<0.85 • 0.4>z>0.7, MX2>2 GeV2 epX Large PT range and full coverage in azimuthal angle f crucial for studies 9 H.Avakian, JLab, Oct 29**cosf moment in ALL-PT-dependence**hep-ph/0608048 m02=0.25GeV2 mD2=0.2GeV2 CLAS PRELIMINARY PT-dependence of cosf moment of double spin asymmetry is most sensitive to kT-distributions of quarks with spin orientations along and opposite to the proton spin. 10 H.Avakian, JLab, Oct 29**A1 PT-dependence in SIDIS**arXiv:1003.4549 0.4<z<0.7 M.Anselmino et al hep-ph/0608048 m02=0.25GeV2 mD2=0.2GeV2 p+ A1 suggests broader kT distributions for f1 than for g1 p- A1 may require non-Gaussian kT-dependence for different helicities and/or flavors H.Avakian, JLab, Oct 29**Lattice**Anselmino Collins A1 PT-dependence arXiv:1003.4549 A1 PT PT CLAS data suggests that width of g1 is less than the width of f1 New CLAS data would allow multidimensional binning to study kT-dependence for fixed x H.Avakian, JLab, Oct 29**Photon Sivers Effect Afanasev & Carlson, Metz & Schlegel,**Gamberg et al. Beam SSA from initial distribution(Boer-Mulders TMD) F.Yuan using h1┴ from MIT bag model Beam SSA: ALU from CLAS @ JLab 0.5<z<0.8 Beam SSA from hadronization (Collins effect) by Schweitzer et al. Collins contribution should be suppressed → g┴ wanted !!! H.Avakian, JLab, Oct 29**Beam SSA: ALU from COMPASS & HERMES**CLAS @4.3GeV No x-dependence? Change the sign at low z? H. Avakian, Frascati, Oct 21**Beam SSA for exclusive pions**W2>4 GeV2,Q2>1 GeV2 Sign flip at z ~ 0.5 4.3 GeV -t < 0.5GeV2 5.7 GeV At z>0.5 struck quark in pion LUND-MC H.Avakian, JLab, Oct 29**Kaon <cos2f> @ HERMES**H.Avakian, JLab, Oct 29**Collins asymmetry - proton**“Kaon puzzle” in spin-orbit correlations Is there a link between HERMES and BRAHMS Kaon vs pion moments (K- has the same sign as K+ and pi+, comparable with K+)? H.Avakian, JLab, Oct 29**Collins effect**kicked in the opposite to the leading pion(into the page) L Sub-leading pion opposite to leading (double kick into the page) Simple string fragmentation (Artru model) p+ Leading pion out of page ( - direction ) z L p- If unfavored Collins fragmentation dominates measured p- vs p+, why K- vs K+ is different? 18 H.Avakian, JLab, Oct 29**B.Musch arXiv:0907.2381**B.Pasquini et al, arXiv:0910.1677 Kotzinian-Mulders Asymmetries HERMES Griffioen CLAS (5 days) Cisbani Worm gear TMDs are unique (no analog in GPDs) H. Avakian, Frascati, Oct 21**CLAS transversely polarized HD-Ice target**HD-Ice target vs std nuclear targets • Small field (∫Bdl~0.005-0.05Tm) • Small dilution (fraction of events from polarized material) • Less radiation length • Less nuclear background (no nuclear attenuation) • Wider acceptance 20 H.Avakian, JLab, Oct 29**Collins SSAs**CLAS E08-015 (2011) H.A.,A.Efremov,P.Schweitzer,F.Yuan Anselmino et al helicity-transversity=pretzelosity CLAS with a transversely polarized target will allow measurements of transverse spin distributions and constrain Collins fragmentation function 21 H.Avakian, JLab, Oct 29**Measurement of Sivers function and GPD-E**CLAS E08-015 (DVCS) (SIDIS) GPD-E=0 DVCS Transverse asymmetry (function of momentum transfer to proton) is large and has strong sensitivity to GPD-E CLAS will provide a measurements of Sivers asymmetry at large x, where the effect is large and models unconstrained by previous measurements. Meissner, Metz & Goeke (2007) 22 H.Avakian, JLab, Oct 29**U**CLAS12 L T q N TMDs program @ 12 GeV in Hall B PAC approved experiments & LoI E12-06-112:Pion SIDIS E12-09-008: KaonSIDIS E12-07-107:Pion SIDIS E12-09-009: KaonSIDIS LOI12-06-108: Pion SIDIS LOI12-09-004: KaonSIDIS • Complete program of TMDs studies for pions and kaons • Kaon measurements crucial for a better understanding of the TMDs “kaon puzzle” • Kaon SIDIS program requires an upgrade of the CLAS12 detector PID RICH detector (Project under development) H.Avakian, JLab, Oct 29**Collins fragmentation: Longitudinally polarized target**Kotzinian-Mulders Asymmetry proton deuteron Pasquini et al. • Study the Collins function of kaons • Provides independent information on the RSMT TMD H.Avakian, JLab, Oct 29**Some questions to address in future**• What is the shape of kT-distributions? • Can kT-distributions be flavor dependent? • Are kT-distributions the same for different spin orientations? • How spin-orbit correlations change the momentum distributions? • How big are quark-gluon correlations? • How nuclear medium changes kT-distributions? • What is the fraction of kT-generated in FSI? • How gluons and sea are distributed in kT How spin-orbit correlations are related to the longitudinal structure and nuclear effects? H.Avakian, JLab, Oct 29**Summary**• CLAS longitudinally polarized NH3 and ND3 target data provides superior sample of events allowing detailed studies of single and double spin asymmetries using multidimensional bins • Measurements of spin and azimuthal asymmetries with unpolarized, longitudinally polarized and transversely polarized targets in semi-inclusive processes at CLAS/CLAS12 will : • Measure TMDs of partons in the valence region • Provide detailed info on partonic spin-orbit correlations • Study quark-gluon correlations (HT) • Study nuclear modification of 3D PDFs We’ll try hard to keep you busy next 10-15 years! H.Avakian, JLab, Oct 29**Support slides….**H.Avakian, JLab, Oct 29**HERMES/COMPASS**Berger H.Avakian, JLab, Oct 29**Longitudinal Target SSA measurements at CLAS**~10% of E05-113 data CLAS-2009 (E05-113) CLAS PRELIMINARY ep→e’pX p1sinf+p2sin2f CLAS-2000 W2>4 GeV2 Q2>1.1 GeV2 y<0.85 p1= 0.059±0.010 p2=-0.041±0.010 p1=-0.042±0.015 p2=-0.052±0.016 p1=0.082±0.018 p2=0.012±0.019 MX>1.4 GeV PT<1 GeV 0.12<x<0.48 0.4<z<0.7 Data consistent with negative sin2f for p+ 30 30 H.Avakian, JLab, Oct 29**B.Musch arXiv:0907.2381**B.Pasquini et al, arXiv:0910.1677 Kotzinian-Mulders Asymmetries HERMES CLAS (5 days) Worm gear TMDs are unique (no analog in GPDs) H.Avakian, JLab, Oct 29**Single hadron production in hard scattering**Target fragmentation h Current fragmentation TMD semi-inclusive exclusive semi-exclusive h FF h DA DA h GPD M PDF 1 -1 xF 0 Fracture Functions kT-dependent PDFs Generalized PDFs You think you understand something? Now check your target fragments! xF>0 (current fragmentation) h xF<0 (target fragmentation) xF- momentum in the CM frame 32 32 H.Avakian, JLab, Oct 29**Quark distributions at large kT**bigger effect at large z PT = p┴+zkT Higher probability to find a hadron at large PT in nuclei kT-distributions may be wider in nuclei? Understanding of modification of kT widths in nuclei is important also for nucleon TMDs 33 33 H.Avakian, JLab, Oct 29**kT and FSI**l’ l total transverse momentum broadening squared x,k’T l’T spectator system nucleus Tang,Wang & Zhou Phys.Rev.D77:125010,2008 l l’ BHS 2002 Collins 2002 Ji,Yuan 2002 x,kT lT ~4 n, with ~4-6 MeV spectator system proton soft gluon exchanges included in the distribution function (gauge link) • The difference is coming from final state interactions (different remnant) • Studies of DIS and SIDIS with nuclear targets provide info on kT 34 H.Avakian, JLab, Oct 29**LTCC**DC R1, R2, R3 CHL-2 PCAL CLAS12 Beam Current: 90 µA Max Pass energy: 2.2 GeV Max Enery Hall A,B,C: 11 GeV Solenoid 5T Primary goal of experiments using CLAS12: study of the internal nucleon dynamics by accessing GPDs & TMDs detector tuned for studies of exclusive and semi-inclusive reactions in a wide kinematic range. Large acceptance detector and high luminosity capabilities EC HTCC FTOF L = 1035 cm-2s-1 CEBAF @ 12 GeV and CLAS12 May 2012 6 GeV Accelerator Shutdown starts May 2013 Accelerator Commissioning starts 2013-2015 Pre-Ops (beam commissioning) H.Avakian, JLab, Oct 29**Structure of the nucleon**You think you understand something? Now add the spin! You think you understand something? Now go 3D! You think you understand something? Now add the strange! You think you understand something? Check the nuclear targets! You think you understand something? Now check your target fragments! H.Avakian, JLab, Oct 29**A.Kotzinian**High statistics of CLAS12 will allow studies of kinematic dependences of the Sivers effect in target fragmentation region Sivers effect in the target fragmentation xF>0 (current fragmentation) xF<0 (target fragmentation) h M Fracture Functions H.Avakian, JLab, Oct 29**Jet limit: Higher Twist azimuthal asymmetries**H.A.,A.Efremov,P.Schweitzer,F.Yuan Phys.Rev.D81:074035,2010 Twist-2 Twist-3 T-odd “interaction dependent” No leading twist, provide access to quark-gluon correlations 39 39 H.Avakian, JLab, Oct 29**ALL PT-dependence in SIDIS**E05-113 M.Anselmino et al hep-ph/0608048 m02=0.25GeV2 mD2=0.2GeV2 0.4<z<0.7 • New experiment with 10 times more data will study the PT-dependence for different quark helicities and flavors for bins in x to check if m0< m2 40 H.Avakian, JLab, Oct 29**SIDIS: partonic cross sections**kT p┴ PT = p┴+zkT Ji,Ma,Yuan Phys.Rev.D71:034005,2005 Is the info on x-kT correlations accessible in kT integrated observables? 41 41 H.Avakian, JLab, Oct 29 H. Avakian, JLab, May 3**Fits to unpolarized data**Anselmino et al Collins et al Extracting widths from A1 Assuming the widths of f1/g1 x,z and flavor independent EMC H.Avakian, JLab, Oct 29**Dilution factor in SIDIS**Fraction of events from polarized hydrogen in NH3 Nu,Np -total counts from NH3 and carbon normalized by lumi ru, rp -total areal thickness of hydrogen (in NH3), and carbon target Cn=Nitr/Carbon ratio (~0.98) Diff. symbols for diff x-bins p- Multiple scattering and attenuation in nuclear environment introduces additional PT-dependence for hadrons H.Avakian, JLab, Oct 29**EMC Effect**I. Cloet (Argonne-2010) • In medium modification • Mass, magnetic moment, size • Form factors, PDFs, GPDs, TMDs, etc • In medium quarks are more relativistic • Dq more sensitive to angular momentum • Lower components of wavefunctions more enhanced • Lower components carry more angular mom. NJL-model How sensitive are inclusive measurements to the transverse structure of nucleon and nucleus ? 44 H.Avakian, JLab, Oct 29 H. Avakian, JLab, May 3

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