Dynamical coupled-channels study of meson production reactions from EBAC@JLab

1. Dynamical coupled-channels study of meson production reactions from EBAC@JLab Hiroyuki Kamano (Excited Baryon Analysis Center, Jefferson Lab) MENU2010, May 31th - June 4th, 2010

2. Outline • Motivation for the N* study at Excited Baryon Analysis Center (EBAC) of Jefferson Lab • Brief review of EBAC analysis in 2007-2009 • (Preliminary) results of KL production reactions

3. “Dynamical coupled-channels model of meson production reactions” A. Matsuyama, T. Sato, T.-S.H. Lee Phys. Rep. 439 (2007) 193 Excited Baryon Analysis Center (EBAC) of Jefferson Lab http://ebac-theory.jlab.org/ Founded in January 2006 Reaction Data • Objectives and goals: • Through the comprehensive analysis • of world dataof pN, gN, N(e,e’) reactions, • Determine N* spectrum (masses, widths) • Extract N* form factors • Provide information about reaction mechanism necessary to interpret the N* properties, structures, dynamical origins Dynamical Coupled-Channels Analysis @ EBAC N* properties Hadron Models Lattice QCD QCD

4. Dynamical coupled-channels model of EBAC(EBAC-DCC model) For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) • Partial wave (LSJ) amplitude of a  b reaction: • Reaction channels: • Transition potentials: coupled-channels effect exchange potentials of ground state mesons and baryons bare N* states

5. EBAC-DCC analysis (2007-2009) Hadronic part pN, hN, ppN (pD,rN,sN) coupled- channels calculations were performed. • p N  pN : fitted to the data up to W = 2 GeV. Julia-Diaz, Lee, Matsuyama, Sato, PRC76 065201 (2007) • p N  pp N : cross sections calculated with the pN model. Kamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC79 025206 (2009) • p N  h N : fitted to the data up to W = 2 GeV Durand, Julia-Diaz, Lee, Saghai, Sato, PRC78 025204 (2008) • g(*) N  p N : fitted to the data up to W = 1.6 GeV and Q2 = 1.5 GeV2 (photoproduction) Julia-Diaz, Lee, Matsuyama, Sato, Smith, PRC77 045205 (2008) (electroproduction)Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki, PRC80 025207 (2009) • g N  pp N : cross sections calculated with the gN & pN model. • Kamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC80 065203 (2009) • Extraction of N* pole positions & new interpretation of dynamical origin of P11 N* states. • Suzuki, Julia-Diaz, Kamano, Lee, Matsuyama, Sato, PRL104 065203 (2010) • Extraction of gN  N* electromagnetic transition form factors. • Suzuki, Sato, Lee, arXiv:0910.1742 [nucl-th] Electromagnetic part Extraction of N* parameters

6. EBAC-DCC analysis (2007-2009) Coupled-channels effect in various reactions Full c.c. effect of ppN(pD,rN,sN) & hN off Full c.c. effect of ppN(pD,rN,sN) & hN off Full c.c effect off

7. EBAC-DCC analysis 2010 ~ EBAC “second generation” model Full combined analysis (global fit) of • N  N (W < 2 GeV) • N  N (W < 2 GeV) • N KY (W < 2 GeV) • N  N (W < 1.6 GeV  2 GeV) • N  N (W < 2 GeV) • N  KY (W < 2 GeV) • pN  ppN (W < 2 GeV) • gN  ppN (W < 1.5 GeV  2 GeV) ~ End of 2010 “Complete experiments” are planned by CLAS. 2010 ~ 2011

8. pi- p  K0 Lambda Preliminary EBAC-DCC Julia-Diaz, Saghai, Lee, Tabakin PRC73 055204

9. gamma p  K+ Lambda Preliminary ds/dW at 1.65 < W < 2 GeV

10. May correspond to new N* states!! Additional bare N* states will be needed to improve the fit to the polarization observables. gamma p  K+ Lambda Formula for calculations of the polarization observables Sandorfi, Hoblit, Kamano, Lee arXiv:0912.3505 [nucl-th] Polarization observables Preliminary P Cx’ Cz’

11. Coupling effect of KY channels on piN PWA Preliminary S11 Re S11 Im P11 Re P11 Im P13 Im P13 Re D13 Re D13 Im D15 Re D15 Im F15 Re F15 Im KY on KY off SAID-EDS F17 Re F17 Im

12. Coupling effect of piN, pipiN, etaN channels on KY observables Preliminary Current EBAC-DCC result Couplings to pN, hN, ppN channels off (At least) about 20% reduction is observed except backward angles.

13. Summary • Full-combined analysis of pN, gN  pN, hN, KY reactions is under way. • Polarization observables will be a key to finding new N* states and complete experiments planned by CLAS are much desired. • Effect of channel couplings (in the current model): • Reaction model is kept improving: • KY channel couplings to pN amps.: Negligible (visible a little in P11,P13) • pN, hN, ppN, channel couplings to KY observables: Visible (~ 20%) • Addnew bare N* states & meson-exchange processes. • Add new reaction channels (wN, KKN, phN,…)

14. Back up

15. Figure: E. Pasyuk’s talk at Hall-B/EBAC meeting “Priority” of coupled-channels effect gN (also pN) reaction cross sections in the resonance region are dominated by pN and ppN final states. At least, the couplings ofpN and ppN channels should be taken into account in the analyses of anygN (pN)  MB reactions.

16. Exchange potentials for channels with strange hadrons 3 diagrams s-ch N u-ch S t-ch K* 4 diagrams s-ch N u-ch X t-ch w t-ch f 5 diagrams s-ch N u-ch X t-ch r t-ch w t-ch f Total 18 diagrams 3 diagrams s-ch N u-ch S u-ch L t-ch K* 3 diagrams s-ch N u-ch X t-ch r At present, KY couples to non-strange channels through pN channel only. (hN  KY is implementing)

17. 2-body “v” potentials (non-strange channels) 5 diagrams s-ch N u-ch N u-ch D t-ch r t-ch s 3 diagrams s-ch N u-ch N t-ch p 2 diagrams s-ch N u-ch N 2 diagrams s-ch N t-ch r 2 diagrams s-ch N u-ch N 2 diagrams s-ch N u-ch N 1 diagram s-ch N 1 diagram s-ch N 2 diagrams s-ch N u-ch N 2 diagrams s-ch N u-ch N 4 diagrams s-ch N u-ch N t-ch p t-ch w 2 diagrams s-ch N u-ch N 2 diagrams s-ch N u-ch N 4 diagrams s-ch N u-ch N u-ch D t-ch r 2 diagrams s-ch N u-ch N Total 36 diagrams

18. gamma N  MB potentials 2 diagrams s-ch N u-ch N 4 diagrams s-ch N u-ch N t-ch r contact 6 diagrams s-ch N u-ch L u-ch S t-ch K t-ch K* contact 5 diagrams s-ch N u-ch N u-ch D t-ch p contact 2 diagrams s-ch N u-ch N 7 diagrams s-ch N u-ch N u-ch D t-ch p t-ch r t-ch s contact 6 diagrams s-ch N u-ch L u-ch S t-ch K t-ch K* contact Total 32 diagrams

19. Coupling effect of piN, pipiN, etaN channels on KY observables Meson-exchange amplitudes Amplitude with Dressed N*

20. Dynamical coupled-channels model of EBAC(EBAC-DCC model) For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) • Partial wave (LSJ) amplitude of a  b reaction: • Reaction channels: • Transition potentials: coupled-channels effect • In future, the form factors will be replaced with those from hadron structure calculationsand the N* structure will be examined. exchange potentials of ground state mesons and baryons bare N* states

21. Stage 1 Construct a reaction model through the comprehensive analysis of meson production reactions Stage 2 Extract resonance informationfrom the reaction model constructed • N* pole positions; N*  gN, MB transition form factors • Confirm/reject N* with low-star status; Search for new N* Stage 3 Make a connection to hadron structure calculations; Explore the structure of the N* states. • CQM, DSE, Large Nc, Soliton models,… • Connection to the Lattice QCD data Strategy for the N* study @ EBAC

22. “Complete Experiment” of pseudoscalar meson photoproduction reactions Measure ALL polarization observables needed to determine amplitudesup tooverall phase “Complete Experiment”= unpolarized diff. crs. sec. single spin beam-target beam-recoil target-recoil 8 /16 observables needed! Chiang, Tabakin PRC55 2054 (1997) • Measurement of gN  KY pol. obs. is very active. • OVER-complete experiments planned by CLAS for g p  K+L, g n  KY. Provides critical information on N*  KY decays !! Much room for new N* state searches