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Overview of the EBACJLAB progress

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T. Sato, N. Suzuki (Osaka) B. Saghai, J. Durand (Saclay) Baryon Resonances ... N. Suzuki, B. Julia-Diaz, H. Kamano, A. Matsuyama, T.-S.H. Lee, T. Sato. ... – PowerPoint PPT presentation

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Title: Overview of the EBACJLAB progress


1
Overview of the EBAC_at_JLAB progress
  • B. Juliá-Díaz
  • Departament dEstructura 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
J1/2
J3/2
J3/2
J1/2
0p
D33 (1700)
S31 (1620)
L1, S1/2, J?3/2-
S11 (1535)
D13 (1520)
L1, S1/2, J?1/2-
L1, S1/2, J?1/2-
L1, S1/2, J?3/2-
0s
P11 (939)
P33 ?(1232)
L0, S1/2, J?1/2
L0, S3/2, J?3/2
qqq
4
The ? (1232) and others
100
? (1232)
pN ? X, pN
  • The Delta (1232) resonance stands as a clear
    peak
  • The region 1.4 GeV 2 GeV hosts 20 resonances

?
5
PDG s and Ns origin
(LIJ)
p
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

Ns
6
Our plan and method
7
EBAC_at_JLAB
Reaction Data
N properties N-N form factors
Lattice QCD
Hadron Models
QCD
8
E.m. probes
  • e.g ?p ???
  • 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?
sTOT (?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) ? 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 CCSL/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
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
  • 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

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 I1/2 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, ps
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 Ns ? All?
?
28
Single pion photoproduction
?p??n
?p??0p
  • Comparison to data
  • Total cross section
  • Differential cross sections
  • Target polarization

sTOT (?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 W1.65 and Q24 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
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
  • Single and double meson production
  • ?N ? ?N up to W1.6 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

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 nucleon resonance region. B. Julia-Diaz, T.-S.H.
Lee, A. Matsuyama, T. Sato, Phys. Rev. C 76,
065201 (2007)
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