1 / 48

Harut Avakian (JLab)

Study of dihadron production at JLab with the 12 GeV CLAS dectector. Harut Avakian (JLab). DiFF Workshop, Pavia, Sep 6, 2011. JLab proposal PR12-11-109 Measure hadron pairs in current and target fragmentation regions

aliza
Download Presentation

Harut Avakian (JLab)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Study of dihadron production at JLab with the 12 GeV CLAS dectector Harut Avakian (JLab) DiFF Workshop, Pavia, Sep 6, 2011 • JLab 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, Pavia, Sep 6

  2. The CLAS Collaboration H. Avakian, Pavia, Sep 6

  3. Outline Introduction Quark-gluon correlations & higher twists in SIDIS Di-hadron production Target Fragmentation Projections for 12 GeV Summary & Plans H. Avakian, Pavia, Sep 6

  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, Pavia, Sep 6

  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, Pavia, Sep 6

  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, Pavia, Sep 6

  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, Pavia, Sep 6 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 Boer-Mulders 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, Pavia, Sep 6

  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, Pavia, Sep 6

  10. Lattice calculations of HT distributions (PDFs in terms of Lorenz invariant amplitudes Musch et al, arXiv:1011.1213) Lattice provides important complementary information on FT for all HT distributions H. Avakian, Pavia, Sep 6

  11. Lattice calculations of HT distributions Lattice provides important cross check with data and models for all HT TMDs (Musch et al, arXiv:1011.1213) Lattice results for u-d can be directly compared to models and data. H. Avakian, Pavia, Sep 6

  12. 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, Pavia, Sep 6

  13. FAST-MC for CLAS12 SIDIS MC in 8D (x,y,z,f,fS,pT,l,p) Simple model with 10% difference between f1 (0.2GeV2) and g1 widths with a fixed width for D1 (0.14GeV2) CLAS12 acceptance & resolutions p┴ Events in CLAS12 PT = p┴+zkT Lund-MC Reasonable agreement of kinematic distributions with realistic LUND simulation H. Avakian, Transversity 2011

  14. BGMP: extraction of kT-dependent PDFs Need: project x-section onto Fourier mods in bT-space to avoid convolution Boer, Gamberg, Musch &Prokudin arXiv:1107.5294 generated acceptance 0.3<x<0.36 0.5<z<0.6 Bessel weighting • provides a model independent way to study kinematical dependences of TMD • requires wide range in hadron PT H. Avakian, Pavia, Sep 6

  15. 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, Pavia, Sep 6

  16. 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, Pavia, Sep 6

  17. Dihadron Fragmentation Dihadron production cross section in case of one photon exchange +.. H. Avakian, Pavia, Sep 6

  18. SSA in Dihadron production Difference of asymmetries measured with unpolarized and longitudinally polarized targets depends only on the DiFF and HT functions H. Avakian, Pavia, Sep 6

  19. Model predictions: unpolarized target Models agree on a large beam SSA for pp pair production H. Avakian, Pavia, Sep 6

  20. 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, Pavia, Sep 6

  21. 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, Pavia, Sep 6

  22. p p Dihadron production at JLab12

  23. 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, Pavia, Sep 6

  24. 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 H. Avakian, Pavia, Sep 6

  25. 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, Pavia, Sep 6

  26. Dihadron production with CLAS12 SU(6) spectator model cQSM JLab PR12-11-109: 54 days of unpolarized proton and deuteron running will allow precision measurement of HT distribution e bag model H. Avakian, Pavia, Sep 6

  27. Azimuthal moments of A1 and flavor decomposition EIC Acceptance in f (and PT) may affect the A1 and flavor decomposition ( in particular Ds extractions using Kaons) in SIDIS? 27

  28. 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 • Higher twists are indispensable part of SIDIS analysis (in particular in JLab kinematics) and their understanding is crucial for interpretation of SIDIS leading twist observables Precision measurement of in ppandpKpairs in DIS will allow us to: Beam request: 56 days of CLAS12@ 11 GeV and NH3(30days) and ND3(50 days) with longitudinally polarized with RICHupgrade H. Avakian, Pavia, Sep 6

  29. Summary-II TODO list for the next PAC • Theory side: • importance of higher twist distributions e and hL (include in EIC program) • importance of DiFFs, relations with Collins • Models for and • Predictions for TFR, possible backgrounds • Lattice extractions, link to FSI (Boer-Mulders and Kotzinian-Mulders forces?). • Experimental side: • extract from the data two pion asymmetries (p+p-,p+p0 pairs) • pKpairs from Belle (BaBar) • p0 Collins • Simulations: • extract e and hL from dihadron MC • extract e and hL from single hadron MC (using BGMP) Prepare a dihadron proposal for the transverse target ! H. Avakian, Pavia, Sep 6

  30. Support slides…. H. Avakian, Pavia, Sep 6

  31. 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, Pavia, Sep 6

  32. Extraction of f1 and g1 TMDs Need: project x-section onto Fourier mods in bT-space to avoid convolution x=0.33 z=0.65 • Bessel weighting: • provides a model independent way to study kinematical dependences of TMDs • requires wide range in hadron PT generated

  33. H. Avakian, Transversity 2011

  34. “flavor blind” HT effects as background: Boer-Mulders distribution Pasquini&Yuan(2010) Gamberg et al (2008) Sun et al (2008) Background contributions : Higher twist azimuthal moments kinematical HT (Cahn) dynamical HT (Berger-Brodsky) Radiative correction Acceptance Wide range in Q2 and PT accessible with CLAS12 are important for cos2f studies (all background contributions are HT) H. Avakian, Transversity 2011

  35. 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 H. Avakian, Pavia, Sep 6

  36. Dihadron simulations with LUND-MC @6 GeV H. Avakian, Pavia, Sep 6

  37. 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, Pavia, Sep 6

  38. HT effects with transverse target H. Avakian, Pavia, Sep 6

  39. Azimuthal moments with unpolarized target quark polarization 39 H. Avakian, Pavia, Sep 6 JLab, Nov 25

  40. Azimuthal moments with unpolarized target quark polarization 40 H. Avakian, Pavia, Sep 6 JLab, Nov 25

  41. SSA with unpolarized target quark polarization 41 H. Avakian, Pavia, Sep 6 JLab, Nov 25

  42. SSA with unpolarized target quark polarization 42 H. Avakian, Pavia, Sep 6 JLab, Nov 25

  43. SSA with long. polarized target quark polarization H. Avakian, Pavia, Sep 6

  44. SSA with long. polarized target quark polarization H. Avakian, Pavia, Sep 6

  45. SSA with unpolarized target quark polarization H. Avakian, Pavia, Sep 6

  46. SSA with unpolarized target quark polarization H. Avakian, Pavia, Sep 6

  47. SSA with transversely polarized target quark polarization H. Avakian, Pavia, Sep 6

  48. Twist-3 PDFs : “new testament” H. Avakian, Pavia, Sep 6

More Related