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More observables to study the nucleon structure with EIC

More observables to study the nucleon structure with EIC. Harut Avakian (JLab). Electron Ion Collider Users Meeting, June 24-27, 2014 at Stony Brook University. Outline. Introduction Hard scattering processes and 3D PDFs Target fragmentation

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More observables to study the nucleon structure with EIC

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  1. More observables to study the nucleon structure with EIC Harut Avakian (JLab) Electron Ion Collider Users Meeting, June 24-27, 2014 at Stony Brook University H. Avakian, EIC@SB, June 26

  2. Outline Introduction Hard scattering processes and 3D PDFs Target fragmentation Hard exclusive pseudoscalar meson production Medium modification of 3D PDFs Summary H. Avakian, EIC@SB, June 26

  3. 12 GeV Approved Experiments by Physics Topics H. Avakian, EIC@SB, June 26

  4. Generalizing 1D PDFs xq(x) • To understand better the dynamics we need • Study orbital motion, move from 1D to 3D • Study interactions and correlations of spin, longitudinal and transverse degrees of freedom • medium modifications of 3D PDFs 1D+3D+medium 3D PDFs in nucleons and nuclei H. Avakian, EIC@SB, June 26

  5. h PDF Single hadron production in hard scattering xF>0 (current fragmentation) h xF<0 (target fragmentation) xF- momentum in the CM frame Target fragmentation Current fragmentation semi-inclusive exclusive h FF DA DA h M GPD 1 -1 xF 0 Fracture Functions kT-dependent PDFs Generalized PDFs Wide kinematic coverage of large acceptance detectors allows studies of hadronization both in the target and current fragmentation regions 5 H. Avakian, EIC@SB, June 26

  6. 3D structure of the nucleon Non-perturbative distributions in hard scattering GPDs TMDs Wigner Distributions ✖ ✖ ✖ ✖ Fracture Functions unpol. quarks in long. pol. nucleon related to OAM! H. Avakian, EIC@SB, June 26

  7. SIDIS kinematical plane and observables Target polarization Cross section is a function of scale variables x,y,z n = E-E’ y = n /E x = Q2 /2Mn z = Eh /n U unpolarized L long.polarized T trans.polarized z Beam polarization TMD structure functions accessible as moments in the azimuthal distributions 7 H. Avakian, EIC@SB, June 26

  8. L production in the target fragmentation region L – unique tool for polarization study due to self-analyzing parity violating decay probability to produce the hadron h when a quark q is struck in a proton target M. Anselmino, V. Barone and A. Kotzinian, Phys. Lett. B 699 (2011) 108 H. Avakian, EIC@SB, June 26

  9. L production in the target fragmentation region polarization tranfer coefficient 60 days of CLAS12 data taking Projected results of the longitudinal spin transfer as a function of xF (red full circles) compared with the CLAS preliminary data and the ISM prediction H. Avakian, EIC@SB, June 26

  10. e p 1 Λ 2 L production in the target fragmentation region at EIC (LEPTO 4x60) e’ direct L p- hyperon decay L H. Avakian, EIC@SB, June 26

  11. Dihadron production asymmetries M. Anselmino, V. Barone and A. Kotzinian, Physics Letters B 713 (2012) The beam–spin asymmetry appears, at leading twist and low transverse momenta, in the deep inelastic inclusive lepto-production of two hadrons, one in the target fragmentation region and one in the current fragmentation region. Target fragmentation may be used to tag the flavor in current fragmentation H. Avakian, EIC@SB, June 26

  12. 3D structure: GPDs epe’pp0 CLAS e1dvcs DVCS asymmetries measured at HERMES & JLAB More measurements at JLab, Compass Transverse photon dominates the x-section for exclusive p0 production Lattice (QCDSF) Spin-azimuthal asymmetries in hard exclusive production of photons and pions give access to underlying GPDs H. Avakian, EIC@SB, June 26

  13. SSAs in exclusive pion production P.Kroll & S. Goloskokov arXiv:0906.0460 Transverse photon matters • The production amplitude at large Q2 factorizes into the hard subprocess and GPDs • Within the handbag approach g*Tp transitions are related to transversity (helicity-flip) GPDs accompanied by a twist-3 pion wave function HERMES Hard partonic subprocess • CLAS12 can measure Q2 dependence of HT SSAs significantly extending the range of CLAS H. Avakian, EIC@SB, June 26

  14. Exclusive kaon production Unlike p+ the K+ x-section is totally dominated by the transverse photon pole contribution negligible Exclusive production of KL and KS provide access to different combinations of chiral-odd GPDs H. Avakian, EIC@SB, June 26

  15. SSAs in exclusive kaon production Goloskokov&Kroll KS asymmetries are predicted to be large and with opposite sign to KL Goldstein, Hernandez, & Liuti Beam and target asymmetries in exclusive production of KL and KS are very sensitive to chiral-odd GPDs. H. Avakian, EIC@SB, June 26

  16. K/K* and L/S separation L S K+ Due to detector resolution clean separation of different channels (L,S,K*) will require detection of 4 particles q L H. Avakian, EIC@SB, June 26

  17. total transverse momentum broadening squared Tang,Wang & Zhou Phys.Rev.D77:125010,2008 kT in medium and FSI kT-distributions wider in nuclei? the intrinsic transverse momentum of partons arises naturally from multiple soft gluon interaction inside the nucleon or nucleus. H. Avakian, EIC@SB, June 26

  18. Approximations on TMDs in medium assume “maximal two gluon approximation” in accounting all higher-twist nuclear multiple parton correlations. simple estimation can reproduce the main features of the data H. Avakian, EIC@SB, June 26

  19. Medium modification and spin observables I. Cloet H.A.,Brodsky,Yuan & Deur • In medium quarks are more relativistic • lower components of quark wavefunctions enhanced • quark lower components have larger angular momentum • quark spin  orbital angular momentum in medium • observables sensitive to orbital motion • will have strongest medium modifications • q- most sensitive to orbital motion • medium modifies the orbital motion Gao, Liang & Wang arXiv:1308.1159 CLAS Preliminary spin and azimuthal asymmetries provide important information on partonic distributions in bound nucleons. H. Avakian, EIC@SB, June 26

  20. Q2 EIC@Jlab/BNL EIC@HIAF ENC@FAIR JLab12 From JLab12 to EIC • JLab@12GeV (25/50/75) • 0.1<xB<0.7: valence quarks • EIC √s = 140, 50, 15 GeV • 10-4<xB<0.3:gluons and quarks, higher PT and Q2. Aybat,Prokudin&Rogers hep:1112.4423 Sun & Yuan arXiv:1304.5037 • Study of high x domain requires high luminosity, low x higher energies • Wide range in Q2 is crucial to study the evolution • Overlap of EIC and JLab12 in the valence region will be crucial for the TMD program H. Avakian, EIC@SB, June 26

  21. Sivers effect in the target fragmentation A.Kotzinian Significant effect predicted in the target fragmentation region, in particular for baryons (target remnant also asymmetric) EIC will allow studies of Q2 dependence of the Sivers effect in the target fragmentation region H. Avakian, EIC@SB, June 26

  22. Summary • EIC provides a unique possibility to study the nucleon structure in target fragmentation region and correlations of target and current fragmentation regions • Orbital motion in medium modifies, making medium modifications of observables sensitive to spin orbit correlations (SSAs) more important for studies of proton structure • Combination of DVCS measurements with measurements of hard-exclusive pseudoscalar mesons with unpolarized, longitudinally and transversely polarized targets would allow precision measurement of all chiral-even and chiral-odd GPDs H. Avakian, EIC@SB, June 26

  23. Support slides…. H. Avakian, EIC@SB, June 26

  24. TMDs in medium: Predictions for CLAS12 Modification of multiplicity in medium and the double-spin asymmetry in medium (A=7) using Eqs.42,45,50 for x = 0.3 and z = 0.5. H. Avakian, EIC@SB, June 26

  25. TMDs in medium: modifications of SSAs SSA are very sensitive to the relative widths of involved nucleon TMDs spin and azimuthal asymmetries provide important information on partonic distributions in bound nucleons. H. Avakian, EIC@SB, June 26

  26. Correlations of spin, longitudinal and transverse degrees • How kT distributions of partons depending on spin and flavor modify in medium? • How studies of proton transverse structure will improve our understanding of medium effects? • How studies of medium modifications will improve our understanding of the proton structure? • Tools: • Polarized and unpolarized SIDIS resolve flavor and spin effects • Polarized SIDIS will help to resolve the spin-orbital effects in medium Joint analysis of polarized and unpolarized target data is crucial for studies of orbital effects in general and medium modification in particular H. Avakian, EIC@SB, June 26

  27. 1D Structure of the Nucleon (+twist-3) quark polarization e nucleon polarization g1 hL gT Quark polarized in the x-direction right after scattering feels a force in the y-direction ~ Burkardt (2008) H. Avakian, EIC@SB, June 26

  28. flavor and spin effects on kT B.Musch et al arXiv:1011.1213 g1q=Dq=(q+-q-)/2 Higher probability to find a quark anti-aligned with proton spin, also more d-quarks at large kT 0 0.5 1.0 N.Makke P. Schweitzer et al arXiv:1210.1267 28 H. Avakian, EIC@SB, June 26

  29. TMD factorization TMD factorization theorem separates a transversely differential cross section into a perturbatively calculable part and several well-defined universal factors corrections for the region of large kT~Q TMDs may in general contain a mixture of both perturbative and non-perturbative contributions Aybat,Collins,Qiu,Rogers 2012 pertutbatively calculable H. Avakian, EIC@SB, June 26

  30. Azimuthal moments in SIDIS quark polarization Higher Twist PDFs Experiment for a given target polarization measures all moments simultaneously 30 H. Avakian, EIC@SB, June 26

  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, EIC@SB, June 26

  32. Forces and binding effects in the partonic medium Interaction dependent parts “Wandzura-Wilczek approximation” is equivalent to setting functions with a tilde to zero. 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) 32 H. Avakian, EIC@SB, June 26

  33. SSAs in exclusive pion production CLAS Preliminary Ahmad,Liuti & Goldstein: arXiv:0805.3568 Gloskokov & Kroll : arXiv:0906.0460 Transverse photon matters HERMES • HT SSAs are expected to be very significant • Wider coverage (CLAS12,EIC) would allow measurements of Q2 dependence of HT SSAs H. Avakian, EIC@SB, June 26

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