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Meson photoproduction and nucleon resonances

Moscow, September 20-23, 2012 XIII International Seminar on Electromagnetic Interactions of Nuclei. Meson photoproduction and nucleon resonances. Eugene Pasyuk Jefferson Lab for the CLAS Collaboration. Outline. Introduction Experimental tools Single pion photporoduction

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Meson photoproduction and nucleon resonances

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  1. Moscow, September 20-23, 2012 XIII International Seminar on Electromagnetic Interactions of Nuclei Meson photoproduction and nucleon resonances Eugene Pasyuk Jefferson Lab for the CLAS Collaboration

  2. Outline E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012 Introduction Experimental tools Single pionphotporoduction K+Lphotoproduction Summary

  3. Photonuclear cross sections E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  4. Baryon Resonance Spectrum N* Constituent quark model Lattice QCD Masses, widths, and coupling constants not well known for many resonances Most models predict more resonance states than observed E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  5. Polarization observables in pseudoscalar meson production 4Complex amplitudes: 16real polarization observables. Complete measurement from 8carefully chosen observables. πN has large cross section but in KY recoil is self-analysing ☻ πN KY recoil targγ γ targrecoil ☻☻☻ ☻☻☻ ☻☻☻ ☻☻☻ ☻☻☻ ☻☻☻ ☻☻☻ ☻☻☻ ☻☻☻ I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B95 347 (1975). Complete, and over-determined circ polarized photons longitudinally polarized target linearly polarized photons transversely polarized target E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  6. From the Experiment to Theory Experiment cross section, spin observables σ,dσ/dΩ,Σ,P,T (beam-target) E,F,G,H, (beam-recoil)Cx,Cz,Ox,Oz, (target-recoil)Lx,Lz, Tx,Tz, Amplitude analysis →multipole amplitudes →phase shifts Reaction Theory dynamical frameworks Theory LQCD, quark models, QCD sum rules, … Coupled channels: resonance parameter Extraction This session Hiroyuki Kamano E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  7. Experimental tools E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  8. CEBAF LINAC LINAC A C B Injector Experimental Halls E: 0.75 –6 GeV Imax: 200μA Duty Cycle: 100% δE/E: 2.5x10-5 Polarization: ≥85% Simultaneous distribution to 3 experimental Halls E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  9. CEBAF Large Acceptance Spectrometer1997-2012 Torus magnet 6 superconducting coils Electromagnetic calorimeters Lead/scintillator, 1296 photomultipliers target + start counter Drift chambers 35,000 cells Time-of-flight counters plastic scintillators, 684 photomultipliers Gas Cherenkov counters e/ separation, 256 PMTs E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  10. Polarized pohoton beam Circular polarization from 100% polarized electron beam Circular polarization Circularly polarized beam produced by longitudinally polarized electrons Linearly polarized photons: coherent bremsstrahlung on oriented diamond crystal E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  11. FROST E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  12. HDIce polarized target HDIce Solid Deuterium-Hydride (HD) – a new class of polarized target Polarized at very high magnetic field and very low temperature Transferred to in-beam cryostat Spin can be moved between H and D with RF transitions All material can be polarized with almost no background E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  13. What we measure with CLAS γp→π0p, π+n γp→ηp γp→ηp γp→KY (K+Λ, K+Σ0, K0Σ+) γp→π+π-p, ωp, ρp, ϕp γn→π-p γn→π+π-n γn→Σ-K+ , ΛK0….. Reactions γp→ηp, ηp, K+Λ provide isospin filter, directly coupled only to N* E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  14. Single pionproduction E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  15. gpp+n •CLAS SP07 MAID07SP08SN08 M. Dugger et al. PRC 79, 065206 (2009) Constrained SAID fit at higher energies. Does not need any new resonances E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  16. pp Photon asymmetry S DE=10 MeV preliminary Michael Dugger, ASU Forum for MAX-IV Ring, Lund, Nov 2011 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  17. pp Photon asymmetry S DE=10 MeV preliminary Michael Dugger, ASU Forum for MAX-IV Ring, Lund, Nov 2011 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  18. gpp+nPhoton asymmetry S DE=10 MeV preliminary Michael Dugger, ASU Forum for MAX-IV Ring, Lund, Nov 2011 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  19. gpp+nHelicityasymmetry E preliminary S. Strauch, USC E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  20. gpp+nHelicity asymmetry E preliminary For W< 1.75 GeV all of the models represent the data fairly well. For W> 1.75 GeV none of the models represents the data well. E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  21. gpp0p Helicity asymmetry E Michael Dugger, ASU E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  22. gpp+nHelicity asymmetry G cos(qp)=-1 to -0.6 cos(qp)=-0.6 to -0.2 cos(qp)=-0.2 to 0.2 PRELIMINARY PRELIMINARY PRELIMINARY cos(qp)=0.6 to 1.0 cos(qp)=0.2 to 0.6 PRELIMINARY PRELIMINARY Jo McAndrew E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  23. gpp+n Target asymmetry T Michael Dugger, ASU E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  24. gpp+n asymmetry F F F F F F F F F F F F F Michael Dugger, ASU E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  25. K+photoproduction E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  26. γpK+Λ Cross Section E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  27. γp→K+Λ: cross section and P g11: W=1.7 – 2.8 GeV (unpolarized beam & target) recoil polarization P excitation function M.E. McCracken et al., PRC 81, 025201 (2010) E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  28. γp→K+Λ: Cx/Cz Nikonovet al’.’s refit of Bonn-Gachina multi-coupled-channel isobar model mix includes: S11 wave, P13(1720), P13(1900), P11(1840) Bradford et al. PRC 75, 035205 (2007), E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  29. γpK+ΛPhoton Asymmetry S preliminary C. Patterson E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  30. K+L Ox C. Patterson preliminary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  31. K+L Oz C. Patterson preliminary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  32. K+L Target Asymmetry C. Patterson preliminary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  33. K+L helicity asymmetry E (PhD L. Casey, CUA) preliminary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  34. K+L helicity asymmetry E (PhD L. Casey, CUA) preliminary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  35. Summary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  36. Status of meson photoproduction ✔ -published✔- acquired E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  37. What was not shown γp→ηp γp→η’p γp→π+π-p ωp, ρp, ϕp γn→π-p γn→π+π-n γn→Σ-K+ , ΛK0 ….. We have measured cross sections an polarization observables E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  38. Conclusion “compete measurement” in pseudoscalar meson photoproductionis reality Data collection with proton and deuteron targets is complete Data are being analyzed E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  39. Extras E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  40. h’ photoproduction • 1968: 11 events from the ABBHHM bubble chamber experiment • 1976: 7 events from the AHHM streamer chamber experiment • 1998: 250 events from the SAPHIR collaboration (first differential cross sections) • 2006: over 2×105 events from the CLAS collaboration • 2009: another few orders of magnitude from CLAS g11 data set E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  41. pp M. Dagger et al. PRL 96, 062001 (2006) SAID MAID NH (K. Nakayama and H. Haberzettl) E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  42. pp M. Duggeret al. PRL 96, 062001 (2006) K. Nakayama and H. Haberzettl, Phys. Rev. C 73, 045211 (2006). Different versions of the model yield similar results for cross section, but quite different predictions for beam asymmetry Predictions for beam asymmetry are quite different E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  43. Variants of model I II III IV V S11(1535) S11(1650) S11(2090) P11(1710) P11(2100) P13(1720) P13(1900) D13(1520) D13(1700) D13(2080) gη´NN= 1.91 S11(1535) S11(1650) S11(2090) P11(1710) P11(2100) P11(2400) P13(1900) D13(1700) D13(2080) gη´NN = 1.33 S11(2090) P11(2100) P13(1900) D13(1700) gη´NN = 0.43 S11(2090) P11(2100) P13(1900) D13(1700) D13(2080) gη´NN = 0.25 S11(1535) S11(2090) P11(1710) P11(2100) D13(1700) D13(2080) gη´NN= 0.002 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  44. pp M. Williams et al. PRC 80, 045213 (2009) E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  45. R Values for the  The  appears 100% polarized when created with a fully polarized beam. E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  46. Average R values Energy and angle averages are consistent with unity. No model predicted this CLAS result. E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

  47. Polarization observables in pseudoscalar meson production E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

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