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Kaon Photoproduction Results from CLAS

Kaon Photoproduction Results from CLAS. D. G. Ireland. “Missing” Baryon Resonances. Resonance Hunting…. Total Cross-sections + differential cross-sections + Partial Wave Analysis +. D(1232) P 33 N(1440)P 11 N(1520)D 13 N(1535)S 11 D (1600)P 33. Cross section.

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Kaon Photoproduction Results from CLAS

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  1. Kaon Photoproduction Results from CLAS D. G. Ireland EuNPC, Bochum

  2. “Missing” Baryon Resonances

  3. Resonance Hunting… Total Cross-sections + differential cross-sections + Partial Wave Analysis + ... D(1232)P33 N(1440)P11 N(1520)D13 N(1535)S11 D(1600)P33 Cross section 0.5 1.0 1.5 Eg (GeV) • Mostly done with pN scattering or photoproduction • Missing resonances may decay through other channels

  4. Meson Photoproduction Cross Sections

  5. Evidence for new resonance? With D13 Without D13 Mart & Benhold, Phys. Rev. C 61 012201(R) (1999)

  6. Transversity Amplitudes } b1 = 1/2[(S1 + S2) + i(N - D)] } b2 = 1/2[(S1 + S2) - i(N - D)] } b3 = 1/2[(S1 - S2) - i(N + D)] } b4 = 1/2[(S1 - S2) + i(N + D)] N, S1,S2, D: Helicity Amplitudes

  7. Experimental Observables

  8. gp →KL Reaction Kinematics K+ proton proton Hyperon is self-analysing Cross Section without target polarisation

  9. CEBAF at Jefferson Laboratory

  10. CLAS

  11. Tagged Photons at CLAS • Eg = E0 – E’ • Circular Polarisation: polarised electron beam, amorphous radiator • Linear polarisation: Crystal (diamond) radiator

  12. gp →KL Cross Section Measurements R. Bradford et al., Phys. Rev. C 73, 035202 (2006).

  13. Recoil Polarisation K+ proton proton Hyperon is self-analysing

  14. Recoil Polarisation (P) gp→KL Kaon-MAID GENT Guidal, Laget, Vanderhaeghen J. McNabb et al. (CLAS) Phys. Rev. C 69, 042201 (2004).

  15. Beam-Recoil Double Polarisation (Cx’,Cz’) K+ proton proton Hyperon is self-analysing

  16. L Polarisation → L fully polarised R. Bradford et al., Phys. Rev. C 75, 035205 (2007).

  17. Photon Beam Asymmetry (S) K+ proton proton

  18. Linear Polarisation analysis Photon Linear Polarisation Particle ID LS0 Thesis work of Craig Paterson (Glasgow)

  19. gp →KL Photon Beam Asymmetry

  20. gp →KL Photon Beam Asymmetry PRELIMINARY

  21. gp →KL Photon Beam Asymmetry PRELIMINARY

  22. Beam-Recoil Double Polarisation (Ox,Oz) K+ proton proton

  23. gp →KL: Extracting Ox and Oz

  24. gp →KL Beam-Recoil Ox and Oz Ox PRELIMINARY Oz PRELIMINARY

  25. Experimental Observables

  26. Data taking completed Currently being analysed Data on quasifree neutron and proton Circular and Linear Polarisation Outlook – Deuterium Target

  27. Outlook – FROzen Spin Target (FROST) Target can be longitudinally or transversely polarised • “Complete” measurement possible • First part of run complete • Undergoing calibration • Second period to run soon…

  28. Conclusions • Kaon Photoproduction results from CLAS: • Published results: s, P, Cx, Cz • Preliminary results: S, T, Ox, Oz • In the near future: • Same set of results for 2H target (quasifree neutron and proton) • “Complete” results (FROST) • Next few years: • Complete set on 2H and p (HDIce)

  29. Backup Slides…

  30. Resonances in Quark Models

  31. Kaon Photoproduction

  32. Contributing Processes + channel coupling…

  33. Helicity Amplitudes } NNo overall helicity flip = |g – (p -L)| } S1Single helicity flip } S2Single helicity flip } DDouble helicity flip

  34. Cross Section Measurements R. Bradford et al., Phys. Rev. C 73, 035202 (2006).

  35. Cross Section Measurements R. Bradford et al., Phys. Rev. C 73, 035202 (2006).

  36. Cross Section Measurements R. Bradford et al., Phys. Rev. C 73, 035202 (2006).

  37. Beam-Recoil Double Polarisation Cz Saclay, Argonne, Pittsburgh GENT Regge+Resonance Kaon-MAID Bonn, Giessen, Gatchina Shklyar Lenske Mosel R. Bradford et al., Phys. Rev. C 75, 035205 (2007).

  38. Beam-Recoil Double Polarisation Cx Saclay, Argonne, Pittsburgh Bonn, Giessen, Gatchina Shklyar Lenske Mosel Regge+Resonance GENT Kaon-MAID R. Bradford et al., Phys. Rev. C 75, 035205 (2007).

  39. Photon Beam Asymmetry

  40. Photon Beam Asymmetry PRELIMINARY

  41. Photon Beam Asymmetry PRELIMINARY

  42. Recoil - Comparison PRELIMINARY g8b ~Factor of 4 increase in statistics from best previous measurements Prev CLAS GRAAL

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