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Semi-Inclusive DIS --opportunities at JLab upgrade

Semi-Inclusive DIS --opportunities at JLab upgrade. Feng Yuan RBRC, Brookhaven National Laboratory. Outline. Introduction Low P ? SIDIS (TMD) High P ? SIDIS (Quark-gluon correlations) Integrated SIDIS (Flavor decomposition) Summary. Inclusive and Semi-inclusive DIS. Inclusive DIS:

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Semi-Inclusive DIS --opportunities at JLab upgrade

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  1. Semi-Inclusive DIS--opportunities at JLab upgrade Feng Yuan RBRC, Brookhaven National Laboratory JLab Hall A Upgrade

  2. Outline • Introduction • Low P? SIDIS (TMD) • High P? SIDIS (Quark-gluon correlations) • Integrated SIDIS (Flavor decomposition) • Summary JLab Hall A Upgrade

  3. Inclusive and Semi-inclusive DIS Inclusive DIS: Partonic Distribution depending on the longitudinal momentum fraction Semi-inclusive DIS: Probe additional information including the transverse distribution JLab Hall A Upgrade

  4. Different P? Region • Integrate out P? -- normal factorization, similar to inclusive DIS • Large P? (ÀQCD) -- hard gluon radiation, can be calculated from perturbative QCD, factorization similar to inclusive DIS • Low P? (»QCD) -- nonperturbative information: new factorization formula • 12GeV ? !12GeV • 12GeV JLab Hall A Upgrade

  5. Semi-Inclusive DIS at Low P? • Transverse Momentum Dependent (TMD) Parton Distributions • Novel Single Spin Asymmetries JLab Hall A Upgrade

  6. TMD Parton Distributions • The gauge invariant definition Belitsky, Ji, Yuan (03) JLab Hall A Upgrade

  7. Polarized TMD Quark Distributions Nucleon Unpol. Long. Trans. Quark Unpol. q(x, k┴) qT(x, k┴) Long. ΔqL(x, k┴) ΔqT(x, k┴) δqT(x, k┴) δqT'(x, k┴) Trans. δq(x, k┴) δqL(x, k┴) Boer, Mulders, Tangerman (96&98) JLab Hall A Upgrade

  8. The Physics We can learn from TMD • Internal structure, transverse momentum dis. • Quark Orbital Angular Momentum e.g, Siver’s function ~ the wave function amplitude with orbital angular momentum!Vanishes if quarks only in s-state! Friends: • Pauli Form Factor F2(t) • Spin-dependent structure function g2(x) • Generalized Parton Distribution E(x, ξ, t) JLab Hall A Upgrade

  9. Connection between TMD and GPD • Wigner distributions After integrating over r, one gets TMD After integrating over k, one gets Fourier transform of GPDs Ji: PRL91,062001(2003) JLab Hall A Upgrade

  10. SIDIS Cross Section At leading power of 1/Q The structure functions depend on Q2, xB, z, Ph? JLab Hall A Upgrade

  11. Low P? SIDIS Factorization Ji, Ma, Yuan, hep-ph/0404183,hep-ph/0405085 JLab Hall A Upgrade

  12. SIDIS: at Large P? • Large P? SIDIS can be calculated from perturbative QCD • Polarized scattering will provide information on the quark-gluon correlations in the nucleon • Single Spin Asymmetry at large P? is not suppressed by 1/Q, but by 1/P? • With enough luminosities, we could measure these asymmetries at large P?at JLab 12GeV? JLab Hall A Upgrade

  13. SSA at Large P? • Qiu-Sterman mechanism • It is suppressed by 1/P? Efremov & Teryaev: 1982 & 1984 Qiu & Sterman: 1991 & 1999 Quark-gluon correlations JLab Hall A Upgrade

  14. Transition from Perturbative region to Nonperturbative region? • Compare different region of P? Nonperturbative TMD Perturbative region JLab Hall A Upgrade

  15. SIDIS: Integrated over P? • The factorization formulas are much simpler • Flavor decomposition for (polarized) PDF Altarelli et al 79 (NLO) Frankfurt et al 89; Melnitchouk et al 98, HERMES, EMC… NLO: de Florian et al 96-98; Leader et al 01; Kretzer 04 JLab Hall A Upgrade

  16. Flavor Decomposition for PDF(Leading Order) • In the valence region (large x), • Isospin relation, Du+=Dd-, favored; Du-=Dd+, unfavored; Du-<< Du+ JLab Hall A Upgrade

  17. Stefan Kretzer “favored” “unfavored” Well described by leading particle ansatz JLab Hall A Upgrade

  18. Continue, • Similarly, from the polarized scattering, d/u at large x!! JLab Hall A Upgrade

  19. Summary • Semi-inclusive DIS at JLab upgrade provides various opportunities to study nucleon structure • Low P? probes TMD parton distributions • High P? probes quark-gluon correlations ? • Integrated P? probes flavor decomposition of PDFs, especially for large x quark and helicity distributions. JLab Hall A Upgrade

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