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M. Contalbrigo, A. Drago and Paolo Lenisa Università di Ferrara and INFN - ITALY

Transverse -sea measurements at JPARC. M. Contalbrigo, A. Drago and Paolo Lenisa Università di Ferrara and INFN - ITALY. XIV International Workshop on Deep Inelastic Scattering (DIS 2006) KEK – April 20-24 2006. Outline. Introduction Double spin asymmetries in DY at JPARC

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M. Contalbrigo, A. Drago and Paolo Lenisa Università di Ferrara and INFN - ITALY

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  1. Transverse-sea measurements at JPARC M. Contalbrigo, A. Drago and Paolo Lenisa Università di Ferrara and INFN - ITALY XIV International Workshop on Deep Inelastic Scattering (DIS 2006) KEK – April 20-24 2006

  2. Outline • Introduction • Double spin asymmetries in DY at JPARC • JPARC vs PAX at GSI • Conclusions

  3. Helicity distributions of valence quarks (rather) well known • Helicity distributions of polarized sea poorly known • Fits: • Models agree with , disagree on the size • Situation more confused for transversity • Models agree within a factor 2 for • Even worse for • Models disagree both on sign of and size. • JPARC: 50 GeV polarized p beam on polarized target: • Double-polarized DY production sensitive to polarized sea (u). Introduction

  4. Std. scenario: Val. scenario: Models: Longitudinal sea M. Glück et al. Phys. Rev. D 63 (2001) 094005

  5. Val. scenario Models: xB xF=x1-x2 D. Dutta et al. LoI for JPARC Std. scenario Double-polarized longitudinal Drell-Yan • Large asymmetries expected at JPARC energy • Test of the assumptions of the fits • Not conclusive distinction between the models

  6. Transverse sea CQSM CDM V. Barone, T. Calarco and A. Drago Phys. Lett. B 390 (1997) 287 M. Wakamatsu and T. Kubota Phys. Rev. D 63 (1999) 034020 • The two models predict different sign for (with comparable amplitude).

  7. 1 1 2 2 xB D. Dutta et al. LoI for JPARC Double-polarized transverse Drell-Yan Asymmetries evoluted with the assumptions: CDM (~CQSM) • Aymmetry is large at JPARC energy (> 0.1) • Sign of the asymmetry will distinguish between the two models. • It will give indications about calculation of sea distributions.

  8. Higher energy p-p machine V. Barone, T. Calarco and A. Drago Phys. Rev. D 56 (1997) 527 • s  • Asymmetry  • ALL>ATT • sJPARC ideal

  9. What about extraction? • Transversity extraction problematic with only p-p scattering • Product of two unknown function. • Summary: Sign of the asymmetries discriminates fits assumption and models • Sinergy with double polarized p-pbar experiment

  10. Facilty for Antiproton and Ion Research (GSI, Darmstadt, Germany) • Proton linac (injector) • 2 synchrotons (30 GeV p) • A number of storage rings •  Parallel beams operation

  11. PAX@GSI • Production of polarized antiprotons by spin filtering • (Tests at COSY (Jülich) and AD (CERN))

  12. P P 0.20 0.20 0.15 0.15 0.10 0.10 0.05 0.05 Model A: T. Hippchen et al., Phys. Rev. C 44, 1323 (1991) Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995) T (MeV) 100 200 50 150 T (MeV) 100 250 200 50 150 Hadronic Interaction: Longitudinal CaseBeam Polarization 3 beam lifetimes Ψacc=20 mrad 2 beam lifetimes Ψacc=10-50 mrad

  13. PAX@GSI Asymmetriccollider: polarized antiprotons in HESR (p=15 GeV/c) polarized protons in CSR (p=3.5 GeV/c) √s=14.5 • Production of polarized antiprotons by spin filtering • (Tests at COSY (Jülich) and AD (CERN))

  14. h1 from pbar-p Drell-Yan at PAX (GSI) Anselmino et al. PLB 594,97 (2004) 10 % precision on the h1u (x) in the valence region

  15. PAX JPARC M2/s=x1x2~0.01-0.3 x1=x2ATTh1u2 Extraction of h1u for x>0.05 Measurement of h1u for 0.15<x<0.5 DY events distribution PAX+JPARC  complete mapping of transversity

  16. Conclusions • Large asymmetries (> 0.10) for d. pol. DY at JPARC • Discrimination between fits assumption and models • Look at the signs of ALL and ATT • Will teach how to calculate antiquark distributions • High complementarity between JPARC and PAX@GSI • Complete mapping of transv. valence + sea polarization

  17. V. Barone et al. hep-ph/0306225

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