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 P. Lenisa
Outline Introduction Double spin asymmetries in DY at JPARC JPARC vs PAX at GSI Conclusions P. Lenisa
Double-polarized DY production sensitive to polarized sea (u). Introduction 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). P. Lenisa
Longitudinal sea Val. scenario: Std. scenario: Models: M. Glück et al. Phys. Rev. D 63 (2001) 094005 P. Lenisa
Double-polarized longitudinal Drell-Yan Models: Val. scenario Std. scenario xF=x1-x2 D. Dutta et al. LoI for JPARC xB Large asymmetries expected at JPARC energy Test of the assumptions of the fits Not conclusive distinction between the models P. Lenisa
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). P. Lenisa
Double-polarized transverse Drell-Yan 1 2 Asymmetries evoluted with the assumptions: CDM 1 D. Dutta et al. LoI for JPARC xB 2 (~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. P. Lenisa
Higher energy p-p machine V. Barone, T. Calarco and A. Drago Phys. Rev. D 56 (1997) 527 s Asymmetry ALL>ATT sJPARC ideal P. Lenisa
Sign of the asymmetries discriminates fits assumption and models Summary: Model DY Asymmetries Fit symm.sea + ALL< 0 ATT< 0 CQSM ALL> 0 CDM ATT> 0 Sign of the asymmetries discriminates fits assumption and models Transversity extraction problematic with only p-p scattering Product of two unknown function. What about extraction? Sinergy with double polarized p-pbar experiment P. Lenisa
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 P. Lenisa
PAX@GSI Production of polarized antiprotons by spin filtering (Tests at COSY (Jülich) and AD (CERN)) P. Lenisa
Hadronic Interaction: Longitudinal Case Beam Polarization Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995) Model A: T. Hippchen et al., Phys. Rev. C 44, 1323 (1991) 50 100 150 200 250 T (MeV) 0.05 0.10 0.15 0.20 P 3 beam lifetimes Ψacc=20 mrad 2 beam lifetimes Ψacc=10-50 mrad P. Lenisa
PAX@GSI Asymmetric collider: Production of polarized antiprotons by spin filtering (Tests at COSY (Jülich) and AD (CERN)) Asymmetric collider: polarized antiprotons in HESR (p=15 GeV/c) polarized protons in CSR (p=3.5 GeV/c) √s=14.5 P. Lenisa
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 P. Lenisa
DY events distribution PAX JPARC Extraction of h1u for x>0.05 x1=x2 ATTh1u2 Measurement of h1u for 0.15<x<0.5 M2/s=x1x2~0.01-0.3 PAX+JPARC complete mapping of transversity P. Lenisa
Large asymmetries (> 0.10) for d. pol. DY at JPARC 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 P. Lenisa
P. Lenisa
V. Barone et al. hep-ph/0306225 P. Lenisa