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CLAS Electroproduction Studies of N* Resonances in the Resonance Region

This study, presented by Kyungseon Joo of the University of Connecticut for the CLAS Collaboration, focuses on N* electroproduction in the resonance region. It includes an analysis of low-lying N* states, hadronic mass transition form factors, and helicity amplitudes for various resonances like Roper P11(1440) and D13(1520). Preliminary data on single pion electroproduction up to the 3rd resonance region is discussed, with details on CLAS experimental setups at differing beam energies and polarizations. The analysis encompasses beam energy ranges, low Q2 values, and experimental results in the D(1232) region and beyond. Current work involves bench-mark studies and pi+ electroproduction, aiming to contribute significantly to the 12 GeV N* program with CLAS12.

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CLAS Electroproduction Studies of N* Resonances in the Resonance Region

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  1. Single p0Electroproduction in the Resonance Region with CLAS Kyungseon Joo University of Connecticut For the CLAS Collaboration N* 2009 Beijing, China April 19, 2009

  2. SU(6)xO(3) Classification of Low Lying N*

  3. CLAS Exclusive Processes in N* Studies p(e,e’)X Hadronic mass

  4. Transition Form Factors of Low Lying N* States pp0 channel is important to study: N* Transition Form Factors in the 2nd Resonance Region – “Roper” P11(1440), S11(1535), D13(1520)

  5. Roper P11(1440) Helicity amplitudes + +

  6. Transverse amplitudes for g*p->D13(1520) + preliminary preliminary

  7. CLAS Single Pion Electro-production Data Data in the D(1232) region up to W = 1.4 GeV

  8. CLAS Single Pion Electro-production Data Data up to the 3rd resonance region up to W = 1.7 GeV

  9. CLAS Single p0 Electro-production Data Analysis • E1E: • Beam Energy:1 GeV and 2 GeV • Low Q2 up to 1.5 GeV, and W up to 1.7 GeV • E1-6: • Beam Energy: 5.75 GeV • Low Q2, up to 4.5 GeV and W up to 2.0 GeV • Beam polarization: ~ 70 – 80 % • Target: Liquid Hydrogen

  10. CEBAF at Jefferson Lab Emax ~ 6 GeV Imax ~ 200 mA Duty Factor ~ 100% sE/E ~ 2.5 10-5 Beam P ~ 80% Eg(tagged) ~ 0.8- 5.5 GeV CLAS B C A

  11. CEBAF Large Acceptance Spectrometer (CLAS) • Six identical sectors • 5 T toroidal B-field • Δθ=15-140 degrees • Δφ= 0-50 degrees • Δp/p = 10-2-10-3

  12. Electron PID

  13. Electron PID

  14. Proton PID Use TOF timing and DC momentum of positive tracks

  15. p0 selection e + p -> e’ + p + X on D(1232) resonance region from 5.7 GeV MX2 MX2 MX2 from e + p -> e’ + p + X on D(1232) resonance region from 2. 0 GeV

  16. p0 selection (E1-6) MX2 from e + p -> e’ + p + X for 1.1 < W < 2.0 GeV Mgg2 MX2 Currently working on bench-mark studies on D(1232) region with/without tagging p0

  17. Typical ep→ e’pπ0 cross sections vs cos θ* and φ* Q2 = 0.2 GeV2 W=1.22 GeV Very preliminary

  18. π+ electroproduction at Q2=0.20 GeV2 using CLAS Very preliminary

  19. Differential Cross section from 2.0 GeV 0.6 < Q2 < 0.7, 1.3 < W < 1.35 Very preliminary

  20. Legendre Moment A0 0.6 < Q2 < 0.7 Very preliminary

  21. pπ0 only nπ+ only pπ0 and nπ+ E1+/M1+ and S1+/M1+ CLAS e1e UIM Fit

  22. Roper P11(1440) Helicity amplitudes + +

  23. Transverse amplitudes for g*p->D13(1520) + preliminary preliminary

  24. Summary • Single p0 electro-production analysis is under way • for low and high Q2 range up to 2.0 GeV in W. • Able to perform combined analysis with np+ and two pion • channels • pp0 channel is an important part of 12 GeV N* program • with CLAS12. • Current pp0 analysis measuring all final states will provide • an important step for 12 GeV N* program.

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