Upload
nelia
View
25
Download
0
Tags:
Embed Size (px)
DESCRIPTION
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). - PowerPoint PPT Presentation
Citation preview
Overview of the EBAC@JLAB progress
B. Juliá-DíazDepartament d’Estructura i Constituents de la MatèriaUniversitat 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)
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Baryon Resonances
ΔNExciting 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:
P11 (939)
0s
0p
L=0, S=1/2, J=1/2+P33 Δ(1232)L=0, S=3/2, J=3/2+
S11 (1535)L=1, S=1/2, J=1/2-
D13 (1520)L=1, S=1/2, J=3/2-
S31 (1620)L=1, S=1/2, J=1/2-
D33 (1700)L=1, S=1/2, J=3/2-
J=1/2 J=3/2 J=3/2 J=1/2
qqq
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
The Δ (1232) and others
• The Delta (1232) resonance stands as a clear peak
• The region 1.4 GeV – 2 GeV hosts ~ 20 resonances
πN
X
, πN
N*: 1440, 1520, 1535, 1650, 1675, 1680, ...
Δ : 1600, 1620, 1700, 1750, 1900, …
Δ (1232)Δ (1232)
100
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
PDG *s and N*’s origin
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 >
π N(LIJ)
N*s
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Our plan and method
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
EBAC@JLAB
N* propertiesN-N* form factors
QQCCDD
Lattice QCDHadron Models
Dynamical Coupled-Channels Analysis @ EBAC
Reaction Data
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
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.
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Multi step (unitarity)
How do we produce meson-baryon states?
• Directly• Through MB states• Through MMB states
• We need to incorporate
all the possibilitiesUnitarity: Coupled-channels
σTOT (b)
p
MS
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
C.C. ingredients
Non-resonant + resonant
Dressed resonant vertex
Resonance self energies
Non-resonant amplitude (resummation)
CC
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
MBMB
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)
CC
Full approach described in great detail:
A. Matsuyama, T. Sato, T.-S.H. Lee, Phys. Rep. 2007
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
i.e. VNN,N
CC
Full approach described in great detail:
A. Matsuyama, T. Sato, T.-S.H. Lee, Phys. Rep. 2007
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Resonance t
CC
Full approach described in great detail:
A. Matsuyama, T. Sato, T.-S.H. Lee, Phys. Rep. 2007
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Dynamical CC|SL/EBAC
∫vgt
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
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Hadronic part(essential starting point)
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Meson-baryon building
N
(1) SAID Energy dependent PWA with fake error bars
(2) SAID Energy independent PWA
(3) EXP DATA
Bg N* param FIT
Fine tune
MINUIT used extensively
REFIT (almost final)
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Technical aspects
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
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
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Meson-baryon
N
EBACSAID06
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Meson-baryon (ii)
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
d/d Polarization
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
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
B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, Phys. Rev. C 76, 065201 (2007)
Real part of the amplitude
N
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
H. Kamano, B. Julia-Diaz, TSH Lee, A. Matsuyama, T. Sato, Phys. Rev. C 79 (2009) 025206
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
(II)
(Using the MB model of BJD, AM, TSHL and TS, Phys. Rev. C 76, 065201 (2007))
Data handled with the help of D. Arndt
Invariant massdistributions
Phase space
Full model
H. Kamano, B. Julia-Diaz, TSH Lee, A. Matsuyama, T. Sato, Phys. Rev. C 79 (2009) 025206
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Properties of N*
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
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 states
Extraction of Resonances from Meson-Nucleon Reactions.N. Suzuki, T. Sato, T.-S.H. Lee, Phys. Rev. C 79 (2009) 025205
Resonance Mass
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Suzuki, BJD, HK, AM,TSHL, TS, in preparation (2009)
Current N*
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Electromagneticpart
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
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?
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Single pion photoproduction
B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, L.C. Smith, Phys. Rev. C77, 045205 (2008)
σT
OT (b
)
p0p Comparison to data Total cross section Differential cross
sections Target polarization
p+n
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Single pion electroproduction
Delta region: We revisited the
original SL model and extracted the form factors of NDelta transition from single Q2 fits.
Julia-Diaz, Lee, Sato, Smith, Phys. Rev. C 75, 015205, (2007)
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
Single pion electroproduction
B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, L.C. Smith, Phys. Rev. C77, 045205 (2008)
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, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
In progress (~ 2009)
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
END
N* properties
N* properties from the EBAC N modelN. 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
B. Julia-Diaz, Overview of the EBAC@JLAB progress, PWA, Bad Honnef 2009
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 reactionsH. 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)