Large-X PDFs in the Drell-Yan Process

1. Large-X PDFs in the Drell-Yan Process Jen-Chieh Peng University of Illinois at Urbana-Champaign “3rd International Workshop on Nucleon Structure at Large Bjorken X” Jefferson Lab, Newport News, Oct. 13-15, 2010

2. Outline •Complementarity between the DIS and the Drell-Yan process for probing parton distributions in nucleon and nuclei • Sea-quark distributions in the medium-X region with Drell-Yan and W-boson production • Parton distributions in nuclei with proton and pion induced Drell-Yan process • Charge-symmetry breaking of parton distributions with the W-boson production • Transverse-momentum-dependent parton distributions with the Drell-Yan process

3. Complimentality between DIS and Drell-Yan Drell-Yan DIS McGaughey, Moss, JCP, Ann.Rev.Nucl. Part. Sci. 49 (1999) 217 Both DIS and Drell-Yan process are tools to probe the quark and antiquark structure in hadrons (factorization, universality) 3

4. Lepton-pair production provides unique information on parton distributions Probe antiquark distribution in nucleon Probe antiquark distribution in pion Probe antiquark distributions in antiproton Unique features of D-Y: antiquarks, unstable hadrons…

5. Fermilab Dimuon Spectrometer (E605 / 772 / 789 / 866 / 906) 5

7. J-PARC 50 GeV 7

8. No nuclear effects ! No assumption of charge-symmetry ! Large Q2 scale !

9. R. Z. Yang, JCP, Perdekamp, PL B680 (2009) 231

10. 300 pb-1 integrated luminosity R. Z. Yang, JCP, Perdekamp, PL B680 (2009) 231

11. Gluon distributions in proton versus neutron? Lingyan Zhu et al., PRL, 100 (2008) 062301 (arXiv: 0710.2344) Gluon distributions in proton and neutron are very similar

12. Charge Symmetry Violation in PDF? See recent review of Londergan, JCP, and Thomas (arXiv:0907.2352)

13. Charge Symmetry violation from MRST Global fits (Eur. Phys. J. C35, 325 (2004)) CSV for sea quarks CSV for valence quarks

14. Comparison between MRST and quark-model calculation Charge symmetry violation for valence quarks MRST Quark-model Eur. Phys. J. C35, 325 (2004) (Rodionov, Thomas, Londergan)

15. Charge symmetry violating Charge-symmetric R. Yang and JCP, preprint

16. Charge symmetry violating Charge-symmetric R. Yang and JCP, preprint

17. Modification of Parton Distributions in Nuclei EMC effect observed in DIS (Ann. Rev. Nucl. Part. Phys., Geesaman, Sato and Thomas) Extensive studies by Kumano et al. and Strikman et al. F2 contains contributions from quarks and antiquarks How are the antiquark distributions modified in nuclei?

18. Drell-Yan on nuclear targets The x-dependence of can be directly measured PRL 83 (1999) 2304 PRL 64 (1990) 2479

19. Flavor dependence of the EMC effects ? Gold nucleus Q2= 10 GeV2 Isovector mean-field generated in Z≠N nuclei can modify nucleon’s u and d PDFs in nuclei Cloet, Bentz, and Thomas, arXiv:0901.3559 SIDIS (JLab proposal) and PVDIS (P.Souder) Pion-induced Drell-Yan ? 19

20. (Dutta, JCP, Cloet, Gaskell, arXiv:1007.3916) W+, W- production in P+A collision is also sensitive to flavor-dependent EMC

21. Probing novel PDFs with the Drell-Yan Related to quark’s transverse momentum and/or transverse spin 1) Transversity 2) Sivers function 3) Boer-Mulders function 21

22. Transversity and Transverse Momentum Dependent PDFs are probed in Semi-Inclusive DIS Unpolarized Boer-Mulders Transversity Polarized target Sivers Polarzied beam and target SL and ST: Target Polarizations;λe: Beam Polarization 22

23. Transversity and Transverse Momentum Dependent PDFs are also probed in Drell-Yan 23

24. Transverse Momentum Dependent PDFs with polarized Drell-Yan 24

25. Boer-Mulders function h1┴from Drell-Yan ● Observation of large cos(2Φ) dependence in Drell-Yan with pion beam ● ● How about Drell-Yan with proton beam? 194 GeV/c π + W Boer, PRD 60 (1999) 014012 25

26. Azimuthal cos2Φ Distribution in p+p and p+d Drell-Yan E866 Collab., Lingyan Zhu et al., PRL 99 (2007) 082301; PRL 102 (2009) 182001 Smallνis observed for p+d D-Y Boer-Mulders function h1┴: ν(π-Wµ+µ-X)~ [valence h1┴(π)] * [valence h1┴(p)] ν(pdµ+µ-X)~ [valence h1┴(p)] * [sea h1┴(p)] Sea-quark BM functions are much smaller than valence quarks 26

27. Results on cos2Φ Distribution in p+p Drell-Yan L. Zhu, J.C. Peng, et al., PRL 102 (2009) 182001 p+p QCD (Boer, Vogelsang; Berger, Qiu, Rodriguez-Pedraza) p+d Combined analysis of SIDIS and D-Y by Melis et al. More data are anticipated from Fermilab E906

28. Transversity and Transverse Momentum Dependent PDFs are also probed in Drell-Yan 28

32. From Y. Goto PAC recommends preparation of full proposal

33. Future prospect for Drell-Yan experiments • Fermilab p+p, p+d, p+A • Unpolarized beam and target • RHIC • Doubly and singly polarized p+p collision • COMPASS • π-p and π-d with polarized targets • FAIR • Polarized antiproton-proton collision • J-PARC • Possibly polarized proton beam and target • JINR • NICA with polarized target • IHEP • SPASCHARM with polarized target p-p and π-p

34. Outstanding questions to be addressed by future Drell-Yan experiments • Does Sivers function change sign between DIS and Drell-Yan? • Does Boer-Mulders function change sign between DIS and Drell-Yan? • Are all Boer-Mulders functions alike (proton versus pion Boer-Mulders functions) • Flavor dependence of TMD functions • Independent measurement of transversity with Drell-Yan

35. Summary • The Drell-Yan process is a powerful experimental tool complementary to the DIS for exploring quark structures in nucleons and nuclei. • Unique information on flavor structures of sea-quark has been obtained with Drell-Yan experiments. First results on TMD have also been extracted. • On-going and future Drell-Yan experiments at various hadron facilities can address many important unresolved issues in the spin and flavor structures of nucleons and nuclei.