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

2. 1 Kaon Photoproduction very high momentum transfer (pQCD)

3. 2

4. Baryon Summary Table (PDG 2008) 3

5. Baryon Summary Table (PDG 2012) 4

6. “Missing” Baryon Resonances 5

7. 6 Resonances in Quark Models

8. Baryon Spectrum on the Lattice 7 Excited state baryon spectroscopy from lattice QCD. Edwards, Dudek, Richards, Wallace Phys. Rev. D 84, 074508 (2011)

9. 8 Resonance Hunting… Mostly done with  N scattering Missing resonances may decay through other channels Total Cross-sections + differential cross-sections + Partial Wave Analysis +...

10. Meson Photoproduction Cross Sections 9

11. Jefferson Lab 10

12. CLAS 11

13. 12  p →KY Electroproduction proton Hyperon is self-analysing Cross Section: … with electron polarization…

14. 13  p →K  Separated Structure Functions D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013

15. 14  p →K  Separated Structure Functions D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013

16. 15  p →K  Q 2 Dependence D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013

17. 16  p →K  Q 2 Dependence D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013

18.  p →K  Photoproduction proton K+K+ Hyperon is self-analysing 17

19. 18 CLAS results γ p → 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. 19 CLAS results γ p → 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. 20 Fit to K + Λ with PDG2010 states < 2 GeV EBAC group: Kamano, Nakamura, Lee, Sato (2012 ) Includes ***, **** states PDG states insufficient to fit KΛ data 1965

22. 21 Evidence for new N* states and couplings State N((mass)J P PDG 2010PDG 2012KΛKΣ Nγ N(1710)1/2 + *** (not seen in GW analysis) *** ***** N(1880)1/2 + ** * N(1895)1/2 - ** **** N(1900)3/2 + ***** ***** N(1875)3/2 - *** ***** N(2150)3/2 - ** N(2000)5/2 + ******* N(2060)5/2 - ******** Bonn-Gatchina Analysis – A.V. Anisovich et al., EPJ A48, 15 (2012) (First coupled-channel analysis that includes nearly all new photoproduction data)

23. Ref: Scaling and Resonances in Elementary K +  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. N*  K +  Amplitude Analysis

24. 23 Linearly Polarized Photons Diamond radiator mounted on target ladder Radiator in goniometer Alignment checked by observing symmetric “Stonehenge Plot” Polarization determined by fit to coherent bremsstrahlung spectrum

25. 24 FROzen Spin Target (FROST) Target can be longitudinally or transversely polarised [See talk by Barry Ritchie]

26. Transversity Amplitudes b 1 = }} } } b 2 = b 3 = b 4 = 25

27. Observables 26

28. Imaging Multi-dimensional Objects 27

29. Imaging Multi-dimensional Objects ? 28

30. Comparison with other measurements 29 ExperimentFinal StateW range (Gev)  PTOxOz CLAS g11 KK 1.62 – 2.84NYNNN KK 1.69 – 2.84NYNNN LEPS KK 1.94 – 2.30YNNNN KK YNNNN GRAAL KK 1.64 – 1.92YYYYY KK 1.74 – 1.92YYNNN CLAS g8 KK 1.71 – 2.19YYYYY KK 1.75 – 2.19YYYYY

31. Comparison with other measurements 30 LEPS CLAS g8 GRAAL

32. Beam Asymmetry Comparison 31

33. Beam-Recoil Comparison 32

34. Beam Asymmetry Comparison 33

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 K  and K  in resonance region Exciting prospect for N* physics (with results from other channels) 34