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Coupled-channels analysis of hadronic and electromagnetic p , h , two- p production reactions

Coupled-channels analysis of hadronic and electromagnetic p , h , two- p production reactions. Hiroyuki Kamano Excited Baryon Analysis Center, Jefferson Lab in collaboration with B. Julia-Diaz, T.-S. H. Lee, A. Matsuyama, T. Sato. DNP08 Oct. 23-26.

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Coupled-channels analysis of hadronic and electromagnetic p , h , two- p production reactions

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  1. Coupled-channels analysis of hadronic and electromagneticp, h, two-p production reactions Hiroyuki Kamano Excited Baryon Analysis Center, Jefferson Lab in collaboration with B. Julia-Diaz, T.-S. H. Lee, A. Matsuyama, T. Sato DNP08 Oct. 23-26

  2. Dynamical Coupled-Channels Analysis @ EBAC Approaches to determining N-N* form factors Reaction Data Electromagnetic N-N* form factors Hadron Models Lattice QCD QCD

  3. Through the dynamical reaction processes, g(*) N  N* bare vertex functions get dressed: = + meson cloud bare Corresponds to the e.m.N-N* transition form factor! Coupled-channels model @ EBAC For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) • Partial wave (LSJ) amplitude of a  b reaction: • Reaction channels: • Potential: coupled-channels effect meson exchange bare N* state

  4. What is needed for extracting electromagnetic N-N* form factors? Before analyzing eN  e’ pN, e’ ppN, … , we need 1. Fixing hadronic parameters 2. Good model to describe gN reactions at Q2 = 0. Pure hadronic process; Determined from pN  pN, ppN, hN • Critical for the model construction • Starting point to explore Q2 > 0 region Determined from gN  pN, ppN, hN

  5. Current status of the analysis @ EBAC Hadronic part • p N  pN : fitted to the SAID PWA up to 2 GeV. Julia-Diaz, Lee, Matsuyama, Sato, PRC76 065201 (2007) • p N  pp N : cross sections calculated; notfitted yet. Kamano, Julia-Diaz, Lee, Matsuyama, Sato, submitted to PRC • p N  h N : fitted to the data up to 2 GeV ( varied only bare N*  hN ) Durand, Julia-Diaz, Lee, Saghai, Sato, PRC78 025204 (2008) • g N  p N : fitted to the data up to 1.6 GeV ( varied only) Julia-Diaz, Lee, Matsuyama, Sato, Smith, PRC77 045205 (2008) • g N  pp N : in progress • g N  h N : in progress Electromagnetic part

  6. pi N  pi N & eta N Julia-Diaz, Lee, Matsuyama, Sato, PRC76 065201 (2007) Durand, Julia-Diaz, Lee, Saghai, Sato, PRC78 025204 (2008) • Five coupled-channels: • Fitted up to 2 GeV Differential cross sections and polarizations are also well reproduced !

  7. gamma N  pi N Julia-Diaz, Lee, Matsuyama, Sato, Smith, PRC77 045205 (2008) • Fitted up to 1.6 GeV. • Only is varied. • Comparison to data • Total cross section • Differential cross section • Photon asymmetry σTOT (b) 

  8. Parameters used in the calculation are from pN  pN analysis. pi N  pi pi N Kamano, Julia-Diaz, Lee, Matsuyama, Sato, submitted to PRC Need combined analysis of p N and pp N !

  9. N-D13(1520) electromagnetic transition amplitude Q2 dependence comes from gNN, gpp, etc. ( well determined ) ( preliminary ) ( preliminary ) total meson cloud bare Need g*N  pN analysis to determine Q2 dependence ofthe bare amplitude !

  10. Improved parameters are applied to(& further retuned by) *N  N (Julia-Diaz, Kamano, Lee, Matsuyama, Sato) (*)N  N (Julia-Diaz, Kamano, Lee, Matsuyama, Sato) N N (Durand, Julia-Diaz, Lee, Saghai, Sato) Extract N-N* electromagnetic transition form factors beyond D !! Outlook Combined analysis of p N  p N, pp N and g N  p N (Julia-Diaz, Kamano, Lee, Matsuyama, Sato) • Retune parameters using the data of all three reactions. • Extends energy region of g N  p N : 1.6  2 GeV

  11. Back up

  12. Pion-nucleon elastic scattering Julia-Diaz, Lee, Matsuyama, Sato, PRC76 065201 (2007) 1340 MeV 1440 MeV 1540 MeV 1680 MeV 1760 MeV 1860 MeV Polarization N

  13. pi N  eta N Durand, Julia-Diaz, Lee, Saghai, Sato, PRC78 025204 (2008)

  14. Key to improving parameters: pp distributions at low W of pi N  pi pi N reaction Kamano, Julia-Diaz, Lee, Matsuyama, Sato, submitted to PRC invariant mass distributions full result phase space Data handled with the help of D. Arndt

  15. Single pion photoproduction reaction Julia-Diaz, Lee, Matsuyama, Sato, Smith, PRC77 045205 (2008) 1513 MeV 1417 MeV 1285 MeV 1232 MeV 1154 MeV 0 0 90 180 0 90 180 1 1 0 0 -1 -1 0 90 180 0 90 180

  16. Parameters used in the calculation are from pN  pN analysis. pi N  pi pi N reaction Kamano, Julia-Diaz, Lee, Matsuyama, Sato, submitted to PRC full result c.c. effect off

  17. gamma N  pi pi N reaction W = 1420 MeV W = 1780 MeV invariant mass distributions (very preliminary) In most energy, • Shape is reasonable. • Magnitude overestimates the data.

  18. Attach appropriate Green functions ( ) and vertex functions ( ) to p N (on-shell) → MB (off-shell) amplitude ( ) Dynamical coupled-channels model for double pion production reactions All ingredientsalready prepared in 2-body calculation !!

  19. Not included in No new parameter introduced Dynamical coupled-channels model for double pion production reactions + 2 → 3 effective potential … + + =

  20. Approximate treatment of direct term = + part of V23 part of

  21. Dynamical coupled-channels modelfor double pion production reactions To obtain g N → p p N amplitude, just make replacement below: where

  22. Results full c.c. effect off res. only nonres. only

  23. Results full res. only nonres. only W = 1790 MeV

  24. Results full res. only nonres. only W = 1440 MeV

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