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Harut Avakian

Semi-inclusive DIS with EIC: Observables and simulations. Harut Avakian. EIC working group meeting, JLab Dec 18. Motivation and observables TMDs and spin-orbit correlations Higher twists in SIDIS MC-simulations Conclusions. EIC medium energy. EIC@JLab. EIC@RHIC. Main Features.

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Harut Avakian

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  1. Semi-inclusive DIS with EIC: Observables and simulations Harut Avakian EIC working group meeting, JLab Dec 18 • Motivation and observables • TMDs and spin-orbit correlations • Higher twists in SIDIS • MC-simulations • Conclusions H. Avakian, JLab, Dec 18

  2. EIC medium energy EIC@JLab EIC@RHIC Main Features • Electron energy: 3-11 GeV • Proton energy: 12-60 GeV • More symmetric kinematics provides better resolution and particle id • Luminosity: few x 1034 cm-2 s-1 • in range around s ~ 1000 GeV2 • Polarized electrons and light ions • longitudinal and transverse • Limited R&D needs • 3 interaction regions (detectors) • Potential upgrade with high-energy ring • Electron energy: 4-20 GeV • Proton energy: 50-250 GeV • More symmetric kinematics provides better resolution and particle id • Luminosity: ~ 1033 cm-2 s-1 • in range around s ~ 1000-10000 GeV2 • Polarized electrons and light ions • longitudinal and transverse • Limited R&D needs • ? interaction regions (detectors) • 90% of hardware can be reused • Most of the slides are for a “generic” US version of an EIC (5x50 or 4x60): • polarized beams (longitudinal and transverse, > 70%) • luminosities of at least 1033 ( ~1034 for exclusive processes) H. Avakian, JLab, Dec 18

  3. Q2 EIC JLab12 Electroproduction kinematics: JLab12→EIC collider experiments H1, ZEUS(EIC) 10-4<xB<0.02 (0.3):gluons (and quarks) in the proton fixed target experiments COMPASS, HERMES  0.006/0.02<xB<0.3 : gluons/valence and sea quarks JLab/JLab@12GeV  0.1<xB<0.7: valence quarks Study of high x domain requires high luminosity, low x higher energies H. Avakian, JLab, Dec 18

  4. Beam polarization Target polarization SIDIS kinematical plane and observables PT U unpolarized L long.polarized T trans.polarized sin(f-fS) moment of the cross section for unpolarized beam and transverse target H. Avakian, JLab, Dec 18

  5. Single hadron production in hard scattering Target fragmentation Current fragmentation semi-inclusive exclusive semi-exclusive h h FF h DA DA h M PDF GPD PDF 1 -1 xF 0 Fracture Functions kT-dependent PDFs Generalized PDFs xF>0 (current fragmentation) h xF<0 (target fragmentation) xF- momentum in the CM frame Measurements in different kinematical regions provide complementary information on the complex nucleon structure. 5 H. Avakian, JLab, Dec 18

  6. JETSET:Single particle production in hard scattering LUND Fragmentation Functions - Before - After Target remnant quark The primary hadrons produced in string fragmentation come from the string as a whole, rather than from an individual parton. H. Avakian, JLab, Dec 18

  7. EIC: Kinematics Coverage e p xF>0 (CFR) 5 GeV 50 GeV xF<0 ( TFR) e’p+X all xF>0 z>0.3 EIC-MC EIC-MC (PYTHIA based) Major part of current particles at large angles in Lab frame (PID at large angles crucial). H. Avakian, JLab, Dec 18

  8. SIDIS: partonic cross sections kT Is this good enough for flavor decomposition? p┴ PT = p┴+zkT 8 H. Avakian, JLab, Dec 18

  9. Flavor Decomposition @ EIC • quark polarization Dq(x) • first 5-flavor separation extraction may have large corrections if there is a strong dependence on PT H. Avakian, JLab, Dec 18

  10. A1 PT-dependence in SIDIS Perturbative limit calculations available for : J.Zhou, F.Yuan, Z Liang: arXiv:0909.2238 M.Anselmino et al hep-ph/0608048 m02=0.25GeV2 mD2=0.2GeV2 • ALL(p) sensitive to difference in kT distributions for f1 and g1 • Wide range in PT allows studies of transition from TMD to perturbative approach 10 H. Avakian, JLab, Dec 18

  11. Quark distributions at large kT: models q Dq Du/u JMR model MR, R=s,a (dipole formfactor), J.Ellis, D-S.Hwang, A.Kotzinian Effect of the orbital motion on the q- may be significant (H.A.,S.Brodsky, A.Deur,F.Yuan 2007) Higher probability to find a quark anti-aligned with proton spin at large kT 11 H. Avakian, JLab, Dec 18

  12. Quark distributions at large kT: lattice Higher probability to find a quark anti-aligned with proton spin at large kT B.Musch arXiv:0907.2381 Higher probability to find a d-quark at large kT 12 H. Avakian, JLab, Dec 18

  13. Quark distributions at large kT: lattice FASTMC Higher probability to find a hadron at large PT in nuclei kT-distributions may be wider in nuclei? Through x-kT correlations also x distributions may be modified in nuclei, EMC? 13 H. Avakian, JLab, Dec 18

  14. fs y PT fS= p/2+fh fS fh x fh y PT fS=p x Collins mechanism for SSA PT FC fragmentation of transversely polarized quarks into unpolarized hadrons FC fh Fragmenting quark polarization x HT function related to force on the quark. M.Burkardt (2008) 14 H. Avakian, JLab, Dec 18

  15. Sivers mechanisms for SSA fS - HT asymmetries (T-odd) PT FS Correlation between quark transverse momentum and the proton spin fkT Proton polarization x No leading twist, provide access to quark-gluon correlations 15 H. Avakian, JLab, Dec 18

  16. PT-dependence of beam SSA ssinfLU(UL) ~FLU(UL)~ 1/Q (Twist-3) In the perturbative limit 1/PT behavior expected 4x60 100 days, L=1033cm-2s-1 Perturbative region Nonperturbative TMD Study for SSA transition from non-perturbative to perturbative regime. EIC will significantly increase the PT range. H. Avakian, JLab, Dec 18

  17. Q2-dependence of beam SSA ssinfLU(UL) ~FLU(UL)~ 1/Q (Twist-3) 1/Qbehavior expected (fixed x bin) Study for Q2 dependence of beam SSA allows to check the higher twist nature and access quark-gluon correlations. H. Avakian, JLab, Dec 18

  18. e p 5-GeV 50 GeV - Boer-Mulders Asymmetry with CLAS12 & EIC Transversely polarized quarks in the unpolarized nucleon sin(fC) =cos(2fh) CLAS12 EIC Perturbative limit calculations available for : J.Zhou, F.Yuan, Z Liang: arXiv:0909.2238 Nonperturbative TMD Perturbative region CLAS12 and EICstudies of transition from non-perturbative to perturbative regime will provide complementary info on spin-orbit correlations and test unified theory (Ji et al) H. Avakian, JLab, Dec 18

  19. positivity bound Pretzelosity @ EIC 5x50 epX p- p+ helicity-transversity=pretzelosity • EIC measurement combined with CLAS12 will provide a complete kinematic range for pretzelosity measurements H. Avakian, JLab, Dec 18

  20. L production in the target fragmentation L polarization in TFR provides information on contribution of strange sea to proton spin (ud)-diquark is a spin and isospin singlet s-quark carries whole spin of L xF- momentum in the CM frame xF(L) Study polarized diquark fracture functions sensitive to the correlations between struck quark transverse momentum and the diquark spin. EIC CLAS12 Wide kinematical coverage of EIC would allow studies of hadronization in the target fragmentation region (fracture functions) H. Avakian, JLab, Dec 18

  21. CLAS12 L S S* EIC4x60 detected Quark Imaging with exclusive processes Rate estimate for KΛ FAST-MC Horn,Cooper Need good resolution to identify exclusive events Using an empirical fit to kaon electroproduction data from DESY and JLab assuming 100 days at a luminosity of 1034, with 5 on 50 GeV (s = 1000) H. Avakian, JLab, Dec 18

  22. Summary • Studies of semi-inclusive and exclusive processes at EIC • Provide detailed info on partonic spin-orbit correlations • Measure transverse momentum distributions of partons at small x • Define quark-gluon correlations and HT using the wide range of Q2 • Investigate hadronization in target fragmentation • For MC-simulation of effects related to the spin, spin orbit and quark-gluon correlations (HT) need updated version of LUND-MC, accounting for realistic transverse momentum distributions of partons in nucleon and nuclei • Need realistic detector simulations (FastMC,Geant4) H. Avakian, JLab, Dec 18

  23. Support slides…. H. Avakian, JLab, Dec 18

  24. p+ p+-p- CLAS12 p- EIC4x60 M(e’p+X) Quark Imaging with exclusive processes • V. Guzey, Ch. Weiss: Regge model • T. Horn: π+ empirical parameterization • More demanding in luminosity • Physics closely related to JLab 6/12 GeV • quark spin/flavor separations • nucleon/meson structure • Simulation for charged p+ production, assuming 100 days at a luminosity of 1034, with 5 on 50 GeV (s = 1000) Horn,Bruell,Weiss H. Avakian, JLab, Dec 18

  25. SSAs in exclusive pion production P.Kroll & S. Goloskokov arXiv:0906.0460 Transverse photon matters HERMES • HT SSAs are expected to be very significant • EIC can measure Q2 dependence of HT SSAs significantly extending the range of CLAS12 H. Avakian, JLab, Dec 18

  26. SSA with long. polarized target quark polarization H. Avakian, JLab, Dec 18

  27. SSA with long. polarized target quark polarization H. Avakian, JLab, Dec 18

  28. SSA with unpolarized target quark polarization H. Avakian, JLab, Dec 18

  29. SSA with unpolarized target quark polarization H. Avakian, JLab, Dec 18

  30. K/K* and L/S separations Detection of K+ crucial for separation of different final states (L,S,K*) H. Avakian, JLab, Dec 18

  31. hep-ph/9606390 Collins effect p+ leading pion out of page Simple string fragmentation for pions (Artru model) z L r production may produce an opposite sign AUT Leading r opposite to leading p(into page) z r L Fraction of direct kaons may be significantly higher than the fraction of direct pions. LUND-MC H. Avakian, JLab, Dec 18

  32. Collins Effect: from asymmetries to distributions need Combined analysis of Collins fragmentation asymmetries from proton and deuteron may provide independent to e+e- (BELLE) Information on the underlying Collins function. H. Avakian, JLab, Dec 18

  33. 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 33 H. Avakian, JLab, Dec 18

  34. Sivers effect in the target fragmentation A.Kotzinian High statistics of CLAS12 will allow studies of kinematic dependences of the Sivers effect in target fragmentation region H. Avakian, JLab, Dec 18

  35. Transverse force on the polarized quarks 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) 35 H. Avakian, JLab, Dec 18 JLab, Nov 25

  36. SSA with unpolarized target quark polarization 36 H. Avakian, JLab, Dec 18 JLab, Nov 25

  37. SSA with unpolarized target quark polarization 37 H. Avakian, JLab, Dec 18 JLab, Nov 25

  38. The Gluon Contribution to the Proton Spin Bruell,Ent Projected data on Dg/g with an EIC, via g + p  D0 + X K- + p+ assuming vertex separation of 100 mm. • Measure 90% of DG (@ Q2 = 10 GeV2) RHIC-Spin Open theoretical problem: At high Q2 one should resum the mass logarithms in g 1 . Since the signs of c(x, Q2) and Δc(x, Q2) are opposite, resummation can affect essentially predicted value ΔG/G ~ g 1 / F2 . RHIC-Spin N.Ya. Ivanov e.a., in preparation 38 H. Avakian, JLab, Dec 18 H. Avakian, Milos, Sep 28

  39. pQCD Predictions Resummation for R= FL/ FT Resummation for F2 For F2 the NLO and resummation contributions are very close CTEQ PDFs used for estimates • N.Ya.Ivanov, Nucl. Phys. B 814 (2009), 142 39 H. Avakian, JLab, Dec 18 H. Avakian, Milos, Sep 28

  40. Resummation for A= 2xFA/ F2 • L.N. Ananikyan, N.Ya. Ivanov,. Nucl.Phys.B762:256-283,2007. CTEQ PDFs used for estimates The mass logarithms resummation (or heavy-quark densities) should reduce the pQCD predictions for R= FL/ FT and A=2xFA/ F2. cos2f moment in charm meson production provides access to charm densities 40 H. Avakian, JLab, Dec 18 H. Avakian, Milos, Sep 28

  41. HERA Q2 27 GeV Q2 EIC ENC ENC EIC JLab (upgraded) compass JLab12 hermes JLab@6GeV Hard Scattering Processes: Kinematics Coverage collider experiments H1, ZEUS(EIC) 10-4<xB<0.02 (0.3):gluons (and quarks) in the proton fixed target experiments COMPASS, HERMES  0.006/0.02<xB<0.3 : gluons/valence and sea quarks JLab/JLab@12GeV  0.1<xB<0.7: valence quarks Study of high x domain requires high luminosity, low x higher energies H. Avakian, JLab, Dec 18

  42. HERA 27 GeV Q2 EIC ENC ENC JLab (upgraded) compass hermes JLab@6GeV Hard Scattering Processes: Kinematics Coverage collider experiments H1, ZEUS(EIC) 10-4<xB<0.02 (0.3):gluons (and quarks) in the proton fixed target experiments COMPASS, HERMES  0.006/0.02<xB<0.3 : gluons/valence and sea quarks JLab/JLab@12GeV  0.1<xB<0.7: valence quarks Q2 EIC(4x60) ENC(3x15) JLab12 Study of high x domain requires high luminosity, low x higher energies H. Avakian, JLab, Dec 18

  43. HERA 27 GeV Q2 Q2 EIC ENC ENC JLab (upgraded) EIC compass hermes ENC JLab@6GeV JLab12 Hard Scattering Processes: Kinematics Coverage collider experiments H1, ZEUS(EIC) 10-4<xB<0.02 (0.3):gluons (and quarks) in the proton fixed target experiments COMPASS, HERMES  0.006/0.02<xB<0.3 : gluons/valence and sea quarks JLab/JLab@12GeV  0.1<xB<0.7: valence quarks Study of high x domain requires high luminosity, low x higher energies H. Avakian, JLab, Dec 18

  44. hep:arXiv-09092238 H. Avakian, JLab, Dec 18

  45. e p 5 GeV 50 GeV Hard Scattering Processes: Kinematics Coverage h Study of high x domain requires high luminosity, low x higher energies H. Avakian, JLab, Dec 18

  46. L polarization in the target fragmentation L polarization in TFR provides information on contribution of strange sea to proton spin xF- momentum in the CM frame Compare x_F with eic! Study polarized diquark fracture functions sensitive to the correlations between struck quark transverse momentum and the diquark spin. Wide kinematical coverage of EIC would allows studies of hadronization in the target fragmentation region H. Avakian, JLab, Dec 18

  47. Structure of nucleon: HERA→JLab→EIC EIC H. Avakian, JLab, Dec 18

  48. EIC@RHIC – an overview Science highlights • Transverse imaging of gluons and sea quarks • Nucleon spin (quark/gluon orbital motion) • Nuclei in QCD (quark/gluon structure) • QCD vacuum in hadron structure and creation Main Features • Electron energy: 4-20 GeV • Proton energy: 50-250 GeV • More symmetric kinematics provides better resolution and particle id • Luminosity: few x 1032 cm-2 s-1 • in range around s ~ 1000-10000 GeV2 • Polarized electrons and light ions • longitudinal and transverse • Limited R&D needs • ? interaction regions (detectors) • 90% of hardware can be reused H. Avakian, JLab, Dec 18

  49. e e’ K+ K*+ Λ production K,K* 1 Λ p 2 π (ud)-diquark is a spin and isospin singlet s-quark carries whole spin of L 6 CLAS 5.7 GeV H. Avakian, JLab, Dec 18

  50. Resummation for R= FL/ FT The Gluon Contribution to the Proton Spin Bruell,Ent Projected data on Dg/g with an EIC, via g + p  D0 + X K- + p+ assuming vertex separation of 100 mm. RHIC-Spin R= FL/ FT • Uncertainties in xDg smaller than 0.01 • Measure 90% of DG (@ Q2 = 10 GeV2) • N.Ya.Ivanov, Nucl. Phys. B 814 (2009), 142 H. Avakian, JLab, Dec 18

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