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Harut Avakian (JLab)

Studies of Dihadron Electroproduction in DIS with Unpolarized and Longitudinally Polarized Hydrogen and Deuterium Targets. Harut Avakian (JLab). PAC38 JLab, Aug 24, 2009. Proposal PR12-11-109 Measure hadron pairs in current and target fragmentation regions

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Harut Avakian (JLab)

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  1. Studies of Dihadron Electroproduction in DIS with Unpolarized and Longitudinally Polarized Hydrogen and Deuterium Targets Harut Avakian (JLab) PAC38 JLab, Aug 24, 2009 • Proposal PR12-11-109 • Measure hadron pairs in current and target fragmentation regions • Study higher-twist distribution functions and interference effects in hadronization Spokespersons: S. Anefalos-Pereira (LNF-INFN) , H. Avakian (JLab), A. Courtoy (U. Pavia) K. Griffioen (W&M), L. Pappalardo (INFN-Ferrara) H. Avakian, JLab , Aug 24

  2. The CLAS Collaboration H. Avakian, JLab , Aug 24

  3. Outline Introduction Quark-gluon correlations & higher twists in SIDIS Di-hadron production Target Fragmentation Projections for 12 GeV Summary Quark-gluon correlations (like kT-effects ) lead to azimuthal modulations in hadron production in hard scattering processes. H. Avakian, JLab , Aug 24

  4. Electroproduction of hadrons production in DIS h PDF h xF>0 (current fragmentation) xF<0 (target fragmentation) xF- momentum in the CM frame Target fragmentation Current fragmentation semi-inclusive exclusive h FF DA h M GPD 1 -1 xF 0 Fracture Functions kT-dependent PDFs Generalized PDFs Measurements in different kinematical regions provide complementary information on the complex nucleon structure. 4 H. Avakian, JLab , Aug 24

  5. First measurements of azimuthal asymmetries in SIDIS Large cosf and sinf modulations have been observed in electroproduction of hadrons in SIDIS with polarized and unpolarized targets HERMES (2000) CLAS (2003) EMC (1987) Related to spin-orbit correlations in fragmentation? H. Avakian, JLab , Aug 24

  6. Beam SSA: ALU from COMPASS & JLab W. Gohn(DIS2011) C.Schill(DIS2011) CLAS HT SSAs are comparable at JLab, HERMES and COMPASS 6 H. Avakian, JLab , Aug 24

  7. Contributions in large sinusoidal modulations observed in experiments from Collins fragmentation fh y PT fS=p x What makes them transversely polarized in the lepton plane? Collins Effect: azimuthal modulation of the fragmentation function FUT∞h1H1┴ sT(q×PT)↔H1┴ y PT fC sT fC fh D(z,PT)=D1(z,PT)+H1┴(z,PT)sin(fh- fS’) hadronizing quark pol. fS’ x fC sin(2fh) H. Avakian, JLab , Aug 24 Collinear twist-3 PDFs

  8. Transverse force on the polarized quarks More sum rules Quark polarized in the x-direction with kT in the y-direction Force on the active quark right after scattering (t=0) Interpreting HT (quark-gluon-quark correlations) as force on the quarks (Burkardt hep-ph:0810.3589) 8 H. Avakian, JLab , Aug 24

  9. Beam SSA: ALU from CLAS @ JLab 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 0.5<z<0.8 Beam SSA from hadronization (Collins effect) by Schweitzer et al. 9 H. Avakian, JLab , Aug 24

  10. Current Fragmentation h Twist-2 Twist-3 A. Bacchetta et al. hep-ph/0611265 • Several unknown distribution and fragmentation functions involved, making extraction model dependent • Factorization of higher twists in kT-dependent SIDIS not proved H. Avakian, JLab , Aug 24

  11. h1 h2 Dihadron Fragmentation - fractions of energy carried by a hadrons • Factorization proven • Evolution known • Extracted at BELLE for pp pairs, • planned for pK pairs Dihadron productions offers exciting possibility to access HT effects H. Avakian, JLab , Aug 24

  12. Dihadron Fragmentation • Significant DiFF published by BELLE • Evolution effects small for DiFF/D1 • DiFF represent the easiest way to measure the polarization of a fragmenting quark • DiFF contain information on interferences between different channels H. Avakian, JLab , Aug 24

  13. Dihadron Fragmentation Dihadron production cross section in case of one photon exchange +.. Higher twist sinf asymmetries have much simpler structure than for single hadron case HT in fragmentation H. Avakian, JLab , Aug 24

  14. SSA in Dihadron production ~ ~ Difference of asymmetries measured with unpolarized and longitudinally polarized targets depends only on the DiFF and HT functions H. Avakian, JLab , Aug 24

  15. Model predictions: unpolarized target Models agree on a large beam SSA for pp pair production H. Avakian, JLab , Aug 24

  16. Model predictions: polarized target • Models agree on a large target SSA for pppair production • Deuteron target measurements provide complementary information on flavor dependence H. Avakian, JLab , Aug 24

  17. Dihadron beam SSA with CLAS6 CLAS-e1dvcs CLAS-e1f p+p- p0p+ preliminary preliminary Significant dihadron asymmetries measured at 6 GeV by CLAS H. Avakian, JLab , Aug 24

  18. p p p K p p Dihadron production with CLAS12 Use the clasDIS (LUND based) generator + FASTMC to study ppandpK pairs xF- momentum in the CM frame CFR-CFR TFR Dihadron sample defined by SIDIS cuts+xF>0 (CFR) for both hadrons H. Avakian, JLab , Aug 24

  19. h1 h2 h1 h2 Hadronization in Current and Target Fragmentation Regions Kp pairs in CFR-CFR and TFR-CFR TFR-CFR CFR-CFR BELLE projections for K+p- TFR formalism based on Fracture Functions developed by Anselmino Barone & Kotzinian arXiv:1107.2292 (2011) Kp pairs will provide complementary information on quark-gluon correlations and hadronization in TFR-CFR and CFR-CFR

  20. Dihadron production with CLAS12 54 days of unpolarized proton 30 days of NH3 CLAS12 will provide precision measurements of single-beam and target asymmetries in dihadron pair production in SIDIS H. Avakian, JLab , Aug 24

  21. Dihadron production with CLAS12 spectator model 54 days of unpolarized proton and deuteron running will allow precision measurement of HT distribution e bag model H. Avakian, JLab , Aug 24

  22. Summary • Provide first measurement of higher twist distributions e and hL describing quark-gluon correlations in nucleon • Study interference effects in hadronization in current and target fragmentation. • Latest experimental data indicate that quark-gluon correlations leading to spin and azimuthal asymmetries may be very significant Beam request: 56 days of CLAS12@ 11 GeV with L=1035cm-2sec-1 with unpolarized hydrogen and deuteron (shared with E12-07-107) and NH3(30days) and ND3(50 days) with longitudinally polarized with RICHupgrade (shared with E12-07-107) Precision measurement of in ppandpKpairs in DIS will allow us to: H. Avakian, JLab , Aug 24

  23. Support slides…. H. Avakian, JLab , Aug 24

  24. Anselmino/Barone/Kotzinian arXiv:1107.2292 (2011) h1 h2 Fracture Function: conditional probabilities to find a quark with certain polarization and longitudinal momentum fraction xB and transverse momentum kT inside a nucleon fragmenting into a hadron carrying a fraction z of the nucleon longitudinal momentum and a transverse momentum PT h1 h2 Hadronization in current and target regions H. Avakian, JLab , Aug 24

  25. Higher Twist SSAs Target sinf SSA (Bacchetta et al. 0405154) Discussed as main sources of SSA due to the Collins fragmentation In jet SIDIS only contributions ~ D1 survive The same unknown fragmentation function Beam sinf SSA With H1┴ (p0)≈0(or measured) Target and Beam SSA can be a valuable source of info on HT T-odd distribution functions

  26. Dihadron simulations with LUND-MC @6 GeV H. Avakian, JLab , Aug 24

  27. cosf azimuthal asymmetries in SIDIS EMC (1987) Large cosf modulations have observed by EMC were reproduced in electroproduction of hadrons in SIDIS with unpolarized targets at COMPASS and HERMES H. Avakian, JLab , Aug 24

  28. 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. 28 H. Avakian, JLab , Aug 24

  29. HT effects with transverse target H. Avakian, JLab , Aug 24

  30. Azimuthal moments with unpolarized target quark polarization 30 H. Avakian, JLab , Aug 24 JLab, Nov 25

  31. Azimuthal moments with unpolarized target quark polarization 31 H. Avakian, JLab , Aug 24 JLab, Nov 25

  32. SSA with unpolarized target quark polarization 32 H. Avakian, JLab , Aug 24 JLab, Nov 25

  33. SSA with unpolarized target quark polarization 33 H. Avakian, JLab , Aug 24 JLab, Nov 25

  34. SSA with long. polarized target quark polarization H. Avakian, JLab , Aug 24

  35. SSA with long. polarized target quark polarization H. Avakian, JLab , Aug 24

  36. SSA with unpolarized target quark polarization H. Avakian, JLab , Aug 24

  37. SSA with unpolarized target quark polarization H. Avakian, JLab , Aug 24

  38. SSA with transversely polarized target quark polarization H. Avakian, JLab , Aug 24

  39. Twist-3 PDFs : “new testament” H. Avakian, JLab , Aug 24

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