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Paolo Lenisa Università di Ferrara and INFN - ITALY

Perspectives for Drell-Yan at FAIR. Paolo Lenisa Università di Ferrara and INFN - ITALY. Studying the hadron structure in DY-reactions CERN – 27.04.10. Rare-Isotope Production Target. Antiproton Production Target. FAIR – Research highlights. Accelerator Physics & Gym :

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Paolo Lenisa Università di Ferrara and INFN - ITALY

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  1. Perspectives for Drell-Yan at FAIR Paolo Lenisa Università di Ferrara and INFN - ITALY Studying the hadron structure in DY-reactions CERN – 27.04.10

  2. Rare-Isotope Production Target Antiproton Production Target FAIR – Research highlights AcceleratorPhysics & Gym: Eight Rings & twoLinacs GSI P-Linac SIS 100/300 SIS 18 FAIR QCD-Phase Diagram:CBM HI beams 2 to 45 AGeV; 400 users UNILAC CBM 100 m ESR Panda PAX Super FRS HESR PP& AP Hadron Structure, QCD & Medium Cooled antiprotons < 15 GeV, 500 users NuclearAstrophys. NUSTAR RI beam- fragmentation; 600 users RESR Warm Dense Plasmas Bunch-compression &Petawatt- Laser250 users CR FLAIR Fundamental Symmetries Ultra-High EM Fields SPARC; FLAIR Antiprotons, Hi-Z ions; 250 users NESR Materials Science, Space- and Radiation Biology (Ion- & antiproton- beams; 350 users DY at FAIR

  3. Antiprotons at FAIR HESR • Antiprotons with 1.5 GeV/c < p < 15 GeV/c • High luminosity: 2·1032 cm-2s-1 • Thick targets: 4·1015 cm-2 • Long beam life time: >30 min • High momentum resolution: p/p ≤ 4·10-5 • Phase space cooling DY at FAIR

  4. Hadron Physics „Dream Machine“ Asymmetric (double-polarized) proton (15 GeV/c) – antiproton (3.5 GeV/c) collider p p DY at FAIR

  5. Outline • DY with polarized antiprotons @ asymmetric collider • Perspectives for single-single spin asymm. @ fixed target • Status of polarized antiprotons studies DY at FAIR

  6. transversely polarised quarks and nucleons Transversity • Probes relativistic nature of quarks • No gluon analog for spin-1/2 nucleon • Different evolution than • Sensitive to valence quark polarization h1 is chirally odd -> it needs a chirally odd partner Inclusive DIS Semi-inclusive DIS Drell-Yan HERMES,COMPASS,JLab DY at FAIR

  7. h1 from p-p  Drell-Yan M invariant Mass of lepton pair Inclusive DIS Semi-inclusive DIS Drell-Yan The “golden-gate” totransversity: DY at FAIR

  8. s=200 GeV2 PAX proposal: Phase II EXPERIMENT: Asymmetric collider: polarized protons in HESR (p=15 GeV/c) polarized antiprotons in CSR (p=3.5 GeV/c) Luminosity: 1.5x1031 cm-2s-1 DY at FAIR

  9. h1u from p-p Drell-Yan at PAX p-p • u-dominance • |h1u|>|h1d| PAX : M2/s=x1x2~0.02-0.3 valence quarks (ATTlarge ~ 0.2-0.3) DY at FAIR

  10. Fermilab E866 800 GeV/c "safe region" Usually taken as Events for Drell-Yan processes CERN NA51 450 GeV/c Q2>4 GeV2 DY at FAIR

  11. s=45 GeV2 s=45 GeV2 s=210 GeV2 s=210 GeV2 Radiative corrections Cross-section Asymmetry Shimizu et al. PRD71 (2005) 114007 DY at FAIR

  12. PAX Detector Concept Physics: h1 distribution sin2q EMFF sin2q pbar-p elastic high |t| Azimuthally Symmetric: BARREL GEOMETRY LARGE ANGLES Experiment:Flexible Facility e+e- Detector: Extremely rare DY signal (10-7 p-pbar) Maximum Bjorken-x coverage (M interval) Excellent PID (hadron/e rejection ~ 104) High mass resolution (≤2 %) Moderate lepton energies (0.5-5 GeV) Magnet: Keeps beam polarization vertical Compatible with Cerenkov Compatible with pol. target TOROID NO FRINGE FIELD DY at FAIR

  13. PAX Detector Concept GEANT simulation (200 mm) Cerenkov (20 mm) Designed for Collider but compatible with fixed target DY at FAIR

  14. q-p Phase Space acceptance Background peaks at * low energy * forward direction DY at FAIR

  15. Background to Drell-Yan e+e- 10 min. experiment: 2∙108 p-pbar interactions several DY events +- ++ & -- combinatorial +charm bckg Background 1:1 to signal after PID, E>300 MeV, conversion veto, mass cut * the combinatorial component can be subtracted (wrong-sign control sample) * the charm can be reduced (vertex decay) DY at FAIR

  16. Resolution Better than 2% mass resol * x dependence of h1 * resonance vs continuum Mandatory to study M below J/ψ mass Vertex resolution high enough to study charm background DY at FAIR

  17. p-p Precision in h1 measurement 1 year of data taking at 15+3.5 GeV collider L = 1.5∙1031 cm-2s-1 p=0.8 pbar=0.15 10 % precision on the h1u (x) in the valence region DY at FAIR

  18. unknown vector coupling, but same Lorentz and spinor structure as other two processes Unknown quantities cancel in the ratios for ATT, but helicity structure remains! More statistics from J/Y… Expected to double the statistics Good mass resolution fundamental DY at FAIR

  19. CDM 1 2 (~CQSM) What about p-p? A. Drago (2006) (Asymmetry evoluted under the assumption: Asymmetries are estimated to be large at PAX energies -> access to RHIC: τ=x1x2~10-3 → sea quarks(ATT ~ 0.01) JPARC/U70: τ=x1x2~10-1 → valence and sea(ATT ~ 0.1) PAX:τ=x1x2~10-1 → valence and sea(ATT ~ 0.1) DY at FAIR

  20. p-p pp, pp, pd: complete mapping of transversity DY events distribution (pp, pp and pd) p-p, p-d M2/s = x1x2 ~ 0.02-0.3 At x1=x2ATT ~ h1u2 Extraction of h1d, h1q for x<0.2 Direct measurement of h1u for 0.05<x<0.5 DY at FAIR

  21. Test of Universality A.V. Efremov et al., Phys. Lett. B 612, 233 (2005) M. Anselmino et al., Phys. Rev. D72, 094007 (2005) Single spin asymmetries: Sivers function from pbar-p or pbar-p Drell-Yan @ PAX DY at FAIR

  22. Fixed target experiments DY at FAIR

  23. DY measurements @ PANDA DY at FAIR

  24. Measurement of Transversity • There is only a single self-sufficient process with a single polarized beam • Single spin-asymmetry in pp or pp Drell-Yan D. Boer, Ferrara (2008) DY at FAIR

  25. A “window” to transversity: pbar - p  l+l- X Only self-sufficient single spin-asymmetry (involves TMDs) Unpolarized DY production cross-section  analogue of BELLE cos2f asymmetry Single-polarized DY production cross-section  analogue of SIDIS Collins asymmetry DY at FAIR

  26. 2 k events/day collider 22 GeV M (GeV/c2) • M2 = s x1x2 • xF=2QL/√s = x1-x2 Kinematics and cross section fixed target DY at FAIR

  27. DY@PANDA: MC – Simulations I A. Bianconi NIM A593, 562 (2008) p p m+m-X Unpolarized case: 5x105 events 1 < qT < 2 GeV/c 2 < qT < 3 GeV/c 1.5 < M2l+l-<2.5 GeV2 qT>1 GeV/c 60o< qCSm+<120o • Luminosity = 2x1032cm-2s-1 • = 0.8 nb • Rate = 0.16 s-1 M. Maggiora Univ. Torino and INFN (I) DY at FAIR

  28. DY@PANDA: MC – Simulations II A. Bianconi, M. Radici Phys. Rev. D71, 074014 (2005) Single-spin asymmetry: p pm+m-X (related to h1T) (related to f1T) 5x105 events 1 < qT < 2 GeV/c 2 < qT < 3 GeV/c DY at FAIR

  29. A polarized target in PANDA? A very difficult task! • Positioning: • Keep good PID for EM physics • No parasitic run possible • Technical issues: • Transport of polarized gas • Compensation of solenoidal field • Pumping of polarized gas • Possible options: • new detector with thoroidal field? • additional IP in HESR? DY at FAIR

  30. Status of polarized antiproton-studies DY at FAIR

  31. Polarized Antiprotons.Two Methods: Loss versus spin flip For an ensemble of spin ½ particles with projections +() and – () Paolo Lenisa DY at FAIR

  32. Spin-filtering Polarization build-upof an initially unpolarized particle beam by repeated passage through a polarized hydrogen target: DY at FAIR

  33. Spin-filtering at TSR: „FILTEX“ – proof-of-principle Polarization buildup process quantitatively understood! F. Rathmann et al., PRL 71, 1379 (1993) →Spin filtering works for protons! PAX submitted new proposal to find out how well spin filtering works for antiprotons (CERN-SPSC-2009-012 / SPSC-P-337) DY at FAIR TSR spin filtering with protons:σexp=73 ± 6 mb Average theoretical value:σtheo=86 ± 2 mb Brief summary in: D. Oellers et al., Phys. Lett. B 674, 269 (2009).

  34. PAX at the CERN-AD (spin filtering with antiprotons) Siberian snake Electron cooler PAX target section DY at FAIR

  35. Experimental Setup for AD Atomic Beam Source Target chamber: Detector system + storage cell • Six additional quadrupoles: • 4 from COSY • 2 from CELSIUS Breit-Rabi Polarimeter DY at FAIR

  36. Spin-dependence of the pbar-p interaction • Measurement of the polarization buildup equivalent to the determination of σ1 and σ2 • Once a polarized antiproton beam is available, spin-correlation data can be measured at AD (50-500 MeV) Model A: T. Hippchen et al., Phys. Rev. C 44, 1323 (1991). Model OBEPF:J. Haidenbauer, K. Holinde, A.W. Thomas, Phys. Rev. C 45, 952 (1992). Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995). DY at FAIR

  37. Spin-filtering studies at COSY- FZJ-Germany Main purpose: Confirm understanding of spin-filtering with protons. Commissioning of the experimental setup for AD Low-βmagnet installation at COSY (summer 2009) Proposal to COSY PAC (submitted in July 2009) Target chamber with storage cell and detector system COSY-Quadupoles ABS BRP Low-β quadrupoles DY at FAIR

  38. Low-b section commissioning (Feb. 2010) Acceptance measurements with scrapers New low-b section Old lattice Low-b section does not limit the machine acceptance DY at FAIR

  39. Conclusions • Outstanding case for DY with polarized antiprotons • Interesting perspectives for DY on fixed target • Polarized target in PANDA technical challenge • Studies on polarized antiprotons undertaken by PAX Collab. DY at FAIR

  40. DY at FAIR

  41. DY at FAIR

  42. Expected polarizations after filtering for two lifetimes at AD transverse longitudinal A D DY at FAIR

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

  44. Background for Total background Background origin x100 x100 x1000 x1000 e e m m Preliminary PYTHIA result (2×109 events) • Background higher for m than for e • Background from charge coniugated mesons negligible for e. DY at FAIR

  45. The PANDA detector DIRC DY at FAIR

  46. From DY to elastic e+e- production: Proton Electromagnetic Form Factors @fixed target DY at FAIR

  47. Background in pbar-p  e+e- DY at FAIR

  48. DY with e+/e- @ PANDA? Pion-rejection promisiong... F. Maas Univ. of Mainz – GSI (D) DY at FAIR

  49. Pbar-p -> e+e- Statistical projection for timelike FF @ PANDA (GE=GM) F. Maas (Mainz+GSI) DY at FAIR

  50. Measurement of GE and GM moduli @ PANDA - Use of different angular dependence for GE and GM F. Maas • Generated events: 2fb-1 (4 months @ 2x1032cm-2s-1) DY at FAIR

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