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Overview of the EBAC@JLAB progress

Overview of the EBAC@JLAB progress. B. Juli á -D í az Departament d’Estructura i Constituents de la Mat è ria Universitat de Barcelona (Spain). The players: H. Kamano (JLab) T.S.H. Lee (Argonne, JLab) A. Matsuyama (Shizuoka) T. Sato, N. Suzuki (Osaka) B. Saghai, J. Durand (Saclay).

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Overview of the EBAC@JLAB progress

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  1. Overview of the EBAC@JLAB progress B. Juliá-Díaz Departament d’Estructura i Constituents de la Matèria Universitat de Barcelona (Spain) The players: • H. Kamano (JLab) • T.S.H. Lee (Argonne, JLab) • A. Matsuyama (Shizuoka) • T. Sato, N. Suzuki (Osaka) • B. Saghai, J. Durand (Saclay)

  2. The problem

  3. Baryon Resonances Exciting the substructure we can learn about the forces which keep the quarks together, e.g. using the quark model picture some of the predicted states are: J=1/2 J=3/2 J=3/2 J=1/2 0p D33 (1700) S31 (1620) L=1, S=1/2, J=3/2- S11 (1535) D13 (1520) L=1, S=1/2, J=1/2- L=1, S=1/2, J=1/2- L=1, S=1/2, J=3/2- 0s P11 (939) P33 Δ(1232) L=0, S=1/2, J=1/2+ L=0, S=3/2, J=3/2+ qqq

  4. N*: 1440, 1520, 1535, 1650, 1675, 1680, ... Δ : 1600, 1620, 1700, 1750, 1900, … The Δ (1232) and others 100 Δ (1232) πN  X, πN • The Delta (1232) resonance stands as a clear peak • The region 1.4 GeV – 2 GeV hosts ~ 20 resonances 

  5. (LIJ) PDG *s and N*’s origin π N • Most of their properties are extracted from • N  N • N  N • Are they all genuine quark/gluon excitations? • |N*> =| qqq > • Is their origin dynamical? • E.g. some could be understood as arising from meson-baryon dynamics • |N*>= | MB > N*s

  6. Our plan and method

  7. Dynamical Coupled-Channels Analysis @ EBAC EBAC@JLAB Reaction Data N* properties N-N* form factors Hadron Models Lattice QCD QCD

  8. E.m. probes e.g: p η • Key points: • Couplings of mesons to baryons • Electromagnetic vertices  • Coupling of resonances to MB • Electromagnetic structure of resonances e.m.

  9. Multi step (unitarity) How do we produce meson-baryon states? • Directly • Through MB states • Through MMB states  • We need to incorporate all the possibilities • Unitarity: Coupled-channels p σTOT (b) MS

  10. C.C. ingredients • Non-resonant + resonant • Dressed resonant vertex • Resonance self energies • Non-resonant amplitude (resummation) CC

  11. MBMB We introduce explicitly (impose) a minimal number of resonances, 16 of 23: (4* and 3 * from PDG): N: S11(2), P11(2), P13(1), D13(1), D15(1), F15(1) Δ: S31(1), P31(1), P33(2), D33(1), F35(1), F37(1) Full approach described in great detail: A. Matsuyama, T. Sato, T.-S.H. Lee, Phys. Rep. 2007 CC

  12. i.e. VNN,N Full approach described in great detail: A. Matsuyama, T. Sato, T.-S.H. Lee, Phys. Rep. 2007 CC

  13. Resonance t Full approach described in great detail: A. Matsuyama, T. Sato, T.-S.H. Lee, Phys. Rep. 2007 CC

  14. Dynamical CC|SL/EBAC Physics: • Unitarity fulfilled within the model • Most relevant channels included • Consistent study of all production reactions • Exact treatment of 3 body cut Technical • Parallel computing version exists • Slow evaluation ∫vgt

  15. Hadronic part(essential starting point)

  16. Meson-baryon building (1) SAID Energy dependent PWA with fake error bars FIT Bg N* param (2) SAID Energy independent PWA REFIT (almost final) MINUIT used extensively (3) EXP DATA Fine tune N

  17. Involved system of coupled integral equations with singularities. No further approximations taken. Need for extensive parameter search. Several unknowns: e.g. couplings of resonances to MB states We developed a parallel code, CCEBA, and got several supercomputing resources Technical aspects • Time gain resulting from using parallel computers scales ~ linearly with the number of processors • First: parallelization in Energy • Second: parallelization in partial wave • BSC, Spain (340 kh), PI: B. Julia-Diaz • NERSC LBNL (500 kh), PI: TSH Lee Tech

  18. Meson-baryon EBAC SAID06 N

  19. Meson-baryon (ii) d/d Polarization B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, Phys. Rev. C 76, 065201 (2007) data obtained through D. Arndt et al, SAID , gwdac.phys.gwu.edu N

  20. Meson-baryon (iii) • Amplitudes compared to GWU/SAID amplitudes for the I=1/2 sector • Total Cross sections compared to experimental data • Prediction for the total cross sections for each individual channel Real part of the amplitude B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, Phys. Rev. C 76, 065201 (2007) N

  21.    H. Kamano, B. Julia-Diaz, TSH Lee, A. Matsuyama, T. Sato, Phys. Rev. C 79 (2009) 025206 

  22.    (II) Invariant mass distributions Full model Phase space H. Kamano, B. Julia-Diaz, TSH Lee, A. Matsuyama, T. Sato, Phys. Rev. C 79 (2009) 025206 (Using the MB model of BJD, AM, TSHL and TS, Phys. Rev. C 76, 065201 (2007)) Data handled with the help of D. Arndt  

  23. Properties of N*

  24. Resonance states Analytic continuation of T(W) to the unphysical sheet by using contour deformation Pole can be both in the non-resonant and resonant amplitudes Pole of T as a function of W, p’s are arbitrary Resonance Mass Extraction of Resonances from Meson-Nucleon Reactions. N. Suzuki, T. Sato, T.-S.H. Lee, Phys. Rev. C 79 (2009) 025205

  25. Current N* Suzuki, BJD, HK, AM,TSHL, TS, in preparation (2009)

  26. Electromagneticpart

  27. Single pion production • Strong pieces fixed • E.g.e.m. vertex of nucleon: fixed  • Electromagnetic structure of resonances Q2 independent analyses? Error? Which N*s ? All? 

  28. Single pion photoproduction p+n • Comparison to data • Total cross section • Differential cross sections • Target polarization p0p σTOT (b) B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, L.C. Smith, Phys. Rev. C77, 045205 (2008) 

  29. Single pion electroproduction • Delta region: • We revisited the original SL model and extracted the form factors of NDelta transition from single Q2 fits. Julia-Diaz, Lee, Sato, Smith, Phys. Rev. C 75, 015205, (2007) 

  30. Single pion electroproduction • On going work: • Fix the strong pieces • Resonance content fixed in strong part • First fit the structure functions available where they have been extracted • First goal is to go up to W=1.65 and Q2=4 GeV2 • Current status • Preliminar Q2 evolution of helicities available • Need to control de error B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, L.C. Smith, Phys. Rev. C77, 045205 (2008) 

  31. Single and double meson production *N  N up to W=1.6 GeV (preparation) H. Kamano, B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato Currently using CLAS structure functions to fix the Q2 evolution of the helicity amplitudes PRELIMINARY RESULTS AVAILABLE *N  N (preparation) B. Julia-Diaz, H. Kamano, A. Matsuyama, T.-S.H. Lee, T. Sato In progress (~ 2009) N* properties • N* properties from the EBAC N model N. Suzuki, B. Julia-Diaz, H. Kamano, A. Matsuyama, T.-S.H. Lee, T. Sato. • Extraction of N* MB and N* N decay vertices B. Julia-Diaz, H. Kamano, A. Matsuyama, T.-S.H. Lee, T. Sato, N. Suzuki END

  32. EBAC progress Extraction of Resonances from Meson-Nucleon Reactions. N. Suzuki, T. Sato, T.-S.H. Lee, Phys. Rev. C 79 (2009) 025205 Dynamical coupled-channels study of pi n --> pi pi n reactions H. Kamano, B. Julia-Diaz, T.-S.H. Lee, A. Matsuyama, T. Sato, Phys. Rev. C 79 (2009) 025206 Coupled-channels study of the pion- p --> eta n process J. Durand, B. Julia-Diaz, T.-S.H. Lee, B. Saghai, T. Sato, Phys. Rev. C 78, 025204 (2008) Dynamical coupled-channels effects in pion photoproduction B. Julia-Diaz, T.-S.H. Lee, A. Matsuyama, T. Sato, and L.C. Smith, Phys. Rev. C 77, 045205 (2008) Dynamical coupled-channels model of pi N scattering in the W <= 2-GeV nucleon resonance region. B. Julia-Diaz, T.-S.H. Lee, A. Matsuyama, T. Sato, Phys. Rev. C 76, 065201 (2007)

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