Kaon Production on the Nucleon

1. Kaon Production on the Nucleon D. G. Ireland Rome, September 30 – October 4, 2013

2. KaonPhotoproduction very high momentum transfer (pQCD)

4. Baryon Summary Table (PDG 2008)

5. Baryon Summary Table (PDG 2012)

6. “Missing” Baryon Resonances

7. Resonances in Quark Models

8. Baryon Spectrum on the Lattice Excited state baryon spectroscopy from lattice QCD. Edwards, Dudek, Richards, Wallace Phys. Rev. D 84, 074508 (2011)

9. Resonance Hunting… Total Cross-sections + differential cross-sections + Partial Wave Analysis + ... • Mostly done with pN scattering • Missing resonances may decay through other channels

10. Meson Photoproduction Cross Sections

11. Jefferson Lab

12. CLAS

13. g*p →KYElectroproduction Cross Section: Hyperon is self-analysing … with electron polarization… proton

14. g*p →KLSeparated Structure Functions D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013

15. g*p →KSSeparated Structure Functions D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013

16. g*p →KLQ2 Dependence D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013

17. g*p →KSQ2 Dependence D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013

18. gp →KLPhotoproduction K+ proton Hyperon is self-analysing proton

19. CLAS results γp→K+Λ→K+pπ- Bonn-Gatchina Coupled Channel Analysis, A.V. Anisovich et al, EPJ A48, 15 (2012) (Includes nearly all new photoproduction data) M. McCracken et al. (CLAS), Phys. Rev. C 81, 025201, 2010

20. CLAS results γp→K+Λ→K+pπ- Bonn-Gatchina Coupled Channel Analysis, A.V. Anisovich et al, EPJ A48, 15 (2012) (Includes nearly all new photoproduction data) M. McCracken et al. (CLAS), Phys. Rev. C 81, 025201, 2010 R. Bradford et al. (CLAS), Phys.Rev. C75, 035205, 2007

21. Fit to K+Λ with PDG2010 states < 2 GeV EBAC group: Kamano, Nakamura, Lee, Sato (2012) Includes ***, **** states 1965 1965 PDG states insufficient to fit KΛ data

22. Evidence for new N* states and couplings Bonn-Gatchina Analysis – A.V. Anisovich et al., EPJ A48, 15 (2012) (First coupled-channel analysis that includes nearly all new photoproduction data)

23. N*  K+L Amplitude Analysis Ref: Scaling and Resonances in Elementary K+L Photoproduction [R.A. Schumacher and M.M. Sargsian, Phys. Rev. C 83, 025207 (2011)] Compute coherent total amplitude: Fit to observed angular distributions: Test various resonance sets vs. mass Free parameters: mass, width, couplings Spin observables neglected Sensitive to smaller contributions to reaction Structure appears when scaling utilised.

24. Linearly Polarized Photons Diamond radiator mounted on target ladder Polarization determined by fit to coherent bremsstrahlung spectrum Alignment checked by observing symmetric “Stonehenge Plot” Radiator in goniometer

25. FROzen Spin Target (FROST) Target can be longitudinally or transversely polarised [See talk by Barry Ritchie]

26. Transversity Amplitudes } b1 = <  | M | > } b2 = <  | M | > } b3 = <  | M | ‖> } b4 = <  | M | ‖>

27. Observables

28. Imaging Multi-dimensional Objects

29. Imaging Multi-dimensional Objects ?

30. Comparison with other measurements

31. Comparison with other measurements LEPS LEPS CLAS g8 CLAS g8 GRAAL GRAAL

32. Beam Asymmetry Comparison Preliminary

33. Beam-Recoil Comparison Preliminary

34. Beam Asymmetry Comparison Preliminary

35. Summary • CLAS has measured a large set of data involving Kaon production • Electroproduction: • Separated structure functions • Q2 dependence – information on form factors • Needs theoretical work • Photoproduction: • Cross sections and recoil polarizations sensitive to N* physics • Exact interpretation of N* spectrum still ambiguous • Outlook: • More polarization data to come (electro- and photo-production) • Results from (quasi-free) neutron • Full set of observables in KL and KS in resonance region • Exciting prospect for N* physics (with results from other channels)