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Quark-quark double scattering in nuclei with twist expansion approach

Quark-quark double scattering in nuclei with twist expansion approach. Ben-Wei Zhang 1. Texas A&M University, USA 2. Central China Normal University, China. Based on the work in collaboration with X.-N. Wang and A. Schaefer. Outline. Introduction

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Quark-quark double scattering in nuclei with twist expansion approach

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  1. Quark-quark double scattering in nuclei with twist expansion approach Ben-Wei Zhang 1. Texas A&M University, USA 2. Central China Normal University, China Based on the work in collaboration with X.-N. Wang and A. Schaefer

  2. Outline • Introduction • Modified FF due to quark-quark scattering with twist expansion approach • Multiplicity ratios of hadrons in nuclei • Summary

  3. parton hadrons ph E Jet Quenching Jet quenching has been observed as a new nuclear phenomenon at RHIC X.N. Wang, Nucl.Phys. A750 (2005) 98

  4. Quark-Quark Double Scattering • Two kinds of double scattering in eA DIS quark-gluon double scattering quark-quark double scattering X.F. Guo, X.N. Wang, PRL85,3591(2000)

  5. Properties of q-q double scattering X.N. Wang and X.F. Guo, NPA 696, 788 (2001) • Quark-quark double scattering will mix the quark and gluon fragmentation functions; Jet conversion; • Quark-quark double scattering may give different modifications to quark FF and anti-quark FF. W. Liu, C.M. Ko, B.W. Zhang, nucl-th/0607047 B.W. Zhang, X.N. Wang, A. Schaefer, in preparation

  6. Generalized Factorization Consider a typical quark-quark double scattering process in semi-inclusive eA DIS: J. Qiu,G. Sterman, NPB 353(1991)105; NPB 353(1991)137

  7. Interference effect interference effect

  8. Other processes lowest order without radiation …… ……

  9. Quark-quark double scattering • Single Scattering: leading twist contribution • Double Scattering: twist-4 contribution

  10. Modified Fragmenation Function • Summing single and double scattering gives • We define the modified quark FF as:

  11. Quark-quark correlation function M. Luo, J. Qiu,G. Sterman, PRD 50(1994)1951. J. Osborne and X.N. Wang, NPA 710(2002)281.

  12. Quark and anti-quark FF(I) • We get the modification to quark FF as: • Similarly we can obtain modification to anti-quark FF.

  13. Quark and anti-quark FF(II) • The difference between modified quark FF and modified anti-quark FF:

  14. Multiplicity ratios of hadrons • Multiplicity ratio measured at HERMES: HERMES hep-ex/0012049 hep-ex/0307023

  15. Theoretical explanation • In the constituent quark model:

  16. Summary • Quark-quark scattering is eA DIS are studied with twist expansion approach • Modification to quark FF in nuclei is different from the modification to anti-quark FF in nuclei. • This difference may explain the multiplicity ratios of hadrons in nuclei observed at HERMES.

  17. Summary (cont.) • Quark-quark double scattering can modify fragmentation functions without radiation. • Quark-quark double scattering may change the flavor of partons: jet conversion • In heavy-ion collisions quark-quark double scattering can not be neglected if quark density is comparable to gluon density in hot nuclear medium.

  18. Thank you! 谢谢！

  19. BACKUP

  20. quark-quark correlation function

  21. Hard partonic part • Semi-inclusive hadronic tensor can be given:

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