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Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

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  1. Epiphany Conference January 6 - 8, 2005, Crakow, Poland COSY-TOF research on Ө+ Wolfgang Eyrich Physikalisches Institut, University of Erlangen, Germany for the COSY-TOF collaboration supported by German BMBF and Forschungszentrum Jülich Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  2. Content • Introduction • The COSY-TOF experiment • Evidence on Θ+ from pp  Σ+K0p • Ongoing and new activities • Outlook Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  3. Introduction Chiral soliton model  antidecuplet including exotic states D. Diakonov, V. Petrov, and M. Polyakov, Z. Phys. A 359 (1997) 305 m ~ 1530 MeV, Γ~ 15 MeV ,S = + 1, Jp = ½+ decayK0p + K+n “anchor”  mass spacing related width:Γ~ 50 MeV Numerous calculations in various models: different masses and widths, splitting, mixing  many questions! Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  4. Strangeness production at COSY-TOF: pN  KYN Information: dynamics + structuredegrees of freedom Meson Exchange Model final state interaction + Search for exotic + Introduction different reaction channels : N = p, n Y = , o, +, - Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  5. Introduction Strangeness production at COSY-TOF: •exclusive observables •full phase-space  Dalitz Plots • polarization: Hyperon-polarization, polarized beam, (polarized target) • threshold region  only few partial waves, no Y* FSI FSI Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  6. threshold COSY limit Introduction Strangeness production in pp  KYN reactions before COSY: almost no data in threshold region Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  7. COSY - Facility Cooler Synchrotron Jülich Circumference: 180 m Phase space cooling: electron and stochastic Beam momentum: maximum:3.6 GeV/c TOF Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  8. COSY - beam Beam-Quality Veto-detector with 2 mm hole 0.1% intensity Beam-Intensity used 1 - 3 x 107 p/s Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  9. COSY - TOF large angle (non magnetic) spectrometer modular vacuum vessel tiny liquid hydrogen target startdetector system stopdetector system Barrel Hodoscope Ring Hodoscope „Erlangen“ Startdetector Neutron Detector LH2Target Beam Central Hodoscope „Quirl“ 3.4 m Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  10. COSY-TOF - Stop-Detector TOF „Quirl“ Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  11. The „Erlangen Start Detector“ delayed decays of K0, Λ charged multiplicity 2  4  trigger vertex reconstruction identification of K0s: decay  „V“ identification of Σ+: decay  kink in track complete geometric reconstruction „4π“ cover Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  12. „Erlangen Start Detector“: Ring microstrip detector Rearside 128 sectors Frontside 100 rings Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  13. „Erlangen Start Detector“: Fibre Hodoscopes Fibre Hodoscope 1 Fibre Hodoscope 2 Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  14. Pbeam = 2.95 GeV/c Monte Carlo simulations Q2 L  pp- K0S p+p- K0S p+p- L  pp- Q1 Q1+ 2 analysis cuts pp Σ+K0p: background separation Separation ofpp  pK0frompp  pK+and pK+S0( g L) detector limits Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  15. pp Σ+K0p: reconstructed masses Pbeam = 2.95 GeV/c Runs 2000 + 2002 events (GeV/c2) K0 – mass Σ+ - mass (GeV/c2) Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  16. Pbeam = 2.95 GeV/c Run 2000 + Run 2002 Σ+ K0 Σ+ K0 939 events 939 events pp Σ+K0p: cuts on masses Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  17. + = pp Σ+K0p: K0p mass spectra Pbeam = 2.95 GeV/c 1.53 significance: 4 – 6 σ (depending on method) Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  18. 1.532 1.532 1.532 M2(K0p) in GeV2/c4 M2(K0p) in GeV2/c4 4.4 4.6 4.8 5.0 5.2 5.4 M2(K0Σ+) in GeV2/c4 M2(Σ+p) in GeV2/c4 pp Σ+K0p: Dalitz plots Pbeam = 2.95 GeV/c Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  19. 1.53 pp Σ+K0p: efficiency corrected K0p spectrum Mass 1530 ± 5 MeV/c² Width ≤ 18 ± 4 MeV/c² (FWHM) Strangeness S = + 1 Cross section: 0.4 ± 0.1stat± 0.1sys µb hep-ex/0403011, Phys. Lett. B 595 (2004), 127 Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  20. Evidence forΘ+ Negativeresults especially from high energy experiments Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  21. New Results on LD2: Nakano et al. Pentaquark04 LEPS 1.53 GeV ! preliminary Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  22. COSY-TOF: Ongoing and new activities In progress Search for possible isospin partnersand Investigation of N* resonances, especially width of N*(1710) Experiment upgrade 2004: Fibre hodoscope with three layers New Measurement 2004: pp Σ+K0p with much higher statistics Independent Analyses Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  23. Pbeam : 2.95 GeV/c3.20 GeV/c3.30 GeV/c 1.532 1.532 1.532 related topic: Search for possible isospin partners search for Ө++ : pp ΛK+p Preliminary: no evidence for Ө++ in pK+ spectra search for Ө+++ : pp  Ө+++ Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  24. pp ΛK+p 1.712 1.712 2.5 3.0 3.5 m2(KЛ) GeV2/c4 related topic: width of N*(1710)resonance Pbeam : 3.30 GeV/c N*(1710) contributes strongly Influence of pΛ-FSI In progress: Investigation of Dalitz plots  width Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  25. Experiment upgrade New fibre hodoscope with three layers →increase of efficiency and purity Two layers Three layers Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  26. Measurement (Oct./Nov. 2004):pp → K0Σ+ p Pbeam= 3.05 GeV/c Estimate of output: Reference: reaction channel pp → K+ Λ p Preliminary analyses of 4 hours run: Λ missing mass Expected overall gain for pp → K0Σ+ p: Factor of ~ 5 more events compared to existing data (in agreement with the proposal) Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  27. Outlook New results expected in the near future confirmation of Θ+ !?  more insight CLAS: high-statistics runs (done, waiting for results) HERMES: higher statistics (done, waiting for results) COSY-TOF: high-statistics run pp Σ+K0p (done, waiting for results) KEK E559: p+p →K-Q+ (run in May 2005) Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  28. Outlook COSY-TOF In the positive case of Θ+ confirmation Future measurements 2005: pn K0p using a LD2 target, successful tests in 2002/04 pol. beam + -polarization  towards parity of 2005/6: pp  Σ+K0p polarized beam + polarized targetparity Experiment upgrade 2005/6: additional tracker 2005/6: polarized target Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  29. pn(p)  pK0Λ(p) Unique signature: 2 „V‘s“ corresponding to delayed decays of Λ and K0 Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen

  30. Pbeam = 2.95 GeV/c Run 2000 ↔ Run 2002 2000 K0 Σ+ 2002 K0 K0 Σ+ pp Σ+K0p: reconstructed masses Epiphany Conference, Cracow, 2005, Wolfgang Eyrich, University of Erlangen