1. Meson spectroscopy with unitary coupled-channels model Satoshi Nakamura Excited Baryon Analysis Center (EBAC), JLab Collaborators : H. Kamano (RCNP), T.-S.H. Lee (ANL), T. Sato (Osaka U)

2. Why hadron spectroscopy ? J PC, spectrum, decay pattern key information Quark-gluon dynamics (QCD) in non-perturbative regime How Partial wave analysis (PWA) Data Reliable analysis tool needed !

3. Analysis of three-meson productions e.g., E852 (BNL)  p     p  Chung et al., PRD 65, 072001 (2001) isobar model *  subsystem forms a resonance * 3rd  is a spectator

4. Question Unitarity ? Coupled-channels ?

5. 3-body unitarity requires … Z-diagrams

6. Question to be addressed How 3-body unitarity makes a difference in extracting hadron properties from data ? Method 1. Construct a unitary and an isobar models 2. Fit them to the same Dalitz plot 3. Extract and compare M* properties from them (pole position, coupling strength to decay channels)

8.  model Coupled-channels eq. for  scattering (L, I ) Fitted to data

22. Coupling strength to decay channels Unitary model Isobar model

23. a 1 (1230)  f 0      Coupling strength to decay channels W=1 GeV  2 (1670)    f 2   Unitary Isobar [degree] W=1.66 GeV