The status of the Excited Baryon Analysis Center
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Transcript of The status of the Excited Baryon Analysis Center
The status of the Excited Baryon Analysis Center
B. Juliá-DíazDepartament d’Estructura i Constituents de la MatèriaUniversitat de Barcelona (Spain)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Summary
• Motivation• Model used at EBAC@JLAB• , ,, production:
Hadronic production Photoproduction Electroproduction *
• Expected during 2010
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 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. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 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)100
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
E.m. probes
• Jefferson LAB (USA)• GRAAL (Grenoble)• MAMI (Mainz)• BATES (MIT)• ELSA (Bonn)• SPring 8 (Japan)
(Courtesy of D. Leinweber)
Originaly, the hope was that probing the structure with electrons would minimize the “hadronic” debris and would give a cleaner access to the properties of nucleons and resonances
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Electroproduction of mesons
*
NN*
NN
M
Main elements:1. Strong-strong interactions2. Hadronic structure of Resonances3. Electromagnetic structure of Resonances
Coupled-channels
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
EBAC plan and method
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
EBAC@JLAB
N* propertiesN-N* form factors
QCD
Lattice QCDHadron Models
Dynamical Coupled-Channels Analysis @ EBAC
Reaction Data
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Formalism (DCC)
Non-resonant + resonant
Dressed resonant vertex
Resonance self energies
Non-resonant amplitude (resummation)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Partial wave amplitude of a b reaction:
Reaction channels:
Potential:
2-body v potential(no N cut) bare N* state2-body Z potential
(with N cut)
EBAC-DCC
A. Matsuyama, T. Sato, T.-S.H. Lee, Phys. Rep. 2007
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
5 diagramss-ch Nu-ch Nu-ch Dt-ch rt-ch s
2 diagramss-ch Nu-ch N
2 diagramss-ch Nu-ch N
3 diagramss-ch Nu-ch Nt-ch
2 diagramss-ch Nu-ch N
2 diagramss-ch Nu-ch N
4 diagramss-ch Nu-ch Nt-ch t-ch w
2 diagramss-ch Nu-ch N
2 diagramss-ch Nu-ch N
2 diagramss-ch Nu-ch N
4 diagramss-ch Nu-ch Nu-ch Dt-ch r
1 diagrams-ch N
1 diagrams-ch N
2 diagramss-ch Nu-ch N
2 diagramss-ch Nt-ch r
Total 36 diagrams
Two body v’s (strong)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
7 diagramss-ch Nu-ch Nu-ch Dt-ch t-ch rt-ch s
contact
2 diagramss-ch Nu-ch N
2 diagramss-ch Nu-ch N
4 diagramss-ch Nu-ch Nt-ch r
contact
Total 20 diagrams
5 diagramss-ch Nu-ch Nu-ch Dt-ch
contact
Two body v’s (e.m.)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
EBAC framework overview
Physics:Non-resonant obtained from phenomenological LagrangiansUnitarity fulfilled within the modelMost relevant channels included
Up to now , , (s, r, D), near future
Consistent study of all production reactionsCorrect treatment of 3 body cut
TechnicalParallel computing version of the codes needed
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Hadronic part(essential starting point)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
MBMB (up to 2 GeV)
We introduce explicitly (impose) a minimal number of bare poles, 16 of 23 (4* and 3* from PDG):N: S11(2), P11(2), P13(1), D13(2),
D15(1), F15(1)Δ: S31(1), P31(1), P33(2), D33(1),
F35(1), F37(1)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Technical aspects
Need for extensive parameter search. Several unknowns: e.g. couplings of resonances to MB states
Supercomputing Resources
NERSC LBNL (>500 kh, 07/10) PI: TSH Lee
BSC, Spain (340 kh, 07/08), PI: B. Julia-Diaz
Involved system of coupled integral equations with singularities.
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
: comparisons to data
EBACSAID06
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Data obtained through R. Arndt et al, SAID , gwdac.phys.gwu.eduB. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, Phys. Rev. C 76, 065201 (2007)
ds/d Polarization
: comparisons to data (ii)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
: comparing amplitudes• Amplitudes compared to
GWU/SAID amplitudes for the I=1/2 sector
B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, Phys. Rev. C 76, 065201 (2007)
Real part of the AmplitudesImaginary part of the Amplitudes
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
: comparing TCS • Total Cross sections
compared to experimental data
B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, Phys. Rev. C 76, 065201 (2007)
• Prediction for the total cross sections for each individual channel
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
: vs other approaches
From M. Paris talk at INT 2009 and R. Arndt talk at Badhonnef 2009
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
TCS s
H. Kamano, B. Julia-Diaz, TSH Lee, A. Matsuyama, T. Sato, Phys. Rev. C 79 (2009) 025206
Not used to constrain the model.
Previous works, mostly tree level:• Meissner et al (1995)• Oset et al (1985)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
, distributions
Data handled with the help of R. 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. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Properties of N*(strong)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
I. Analytic continuation of T(W) to the unphysical sheet by using contour deformation
II. Poles can be both in the non-resonant and resonant amplitudesIII. One can search for poles 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; arXiv:0910.1742, part of Suzuki’s PhD Thesis
Resonance Mass
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
N. Suzuki, B. Julia-Diaz, H. Kamano, A. Matsuyama, TSH Lee, T Sato, arXiv: 0909.1356
Dynamical origin of N(1440)
polesEBAC 1357 - i 76 1364 - i 105
R. A. Arndt et al.(SAID) 1359 - i 82 1388 - i 83
M. Doring et al.(JUELICH) 1387 - i 147/2 1387 - i 71
1. Within our framework the three P11 states evolve from the same bare state.
2. In the fig: evolution of the pole position as we increase the self energy
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
EBAC current N*
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Electromagnetic part
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Goal:E.m. meson production
Make use of the vast database for single and double pion photo and electroproduction reactions (JLAB, ELSA, MAMI, …) to:
1) Look for yet unseen resonances2) Confirm the existence of the N*s seen
in the hadronic reactions3) Extract resonance properties:
a) Couplings to meson-baryonb) Electromagnetic structure
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Schematic view
*
NN*
N
Consequence of Unitarity
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Data considered:– Differential cross sections
– p 0 p (8793)– p + n (5063)
– Photon asymmetry (Sigma)– p 0 p(1204)– p + n (881)
Consider up to W = 1.6 GeV.
Single pion photoproduction
Analysis performed at specific energies.
B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, L.C. Smith, Phys. Rev. C77, 045205 (2008)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, L.C. Smith, Phys. Rev. C77, 045205 (2008)
σ TO
T (b
)
p0p Comparison to data• Total cross section• Differential cross
sections• Target polarization
p+n
Single pion photoproduction
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Electroproduction
Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki, Phys. Rev. C 80, 025207 (2009).
1. Fit1: sT+ sL , sLT , sTT , p(e,e’0)p [Joo et al. PRL02]
2. Fit2 all p(e,e’+)n, p(e,e’0)p3. Fit3 p(e,e’0)p [Joo et al. PRL (2002 & 2003)]
• Consider W<1.65 MeV and Q2<1.45 GeV2
• No assumption on the Q2 dependence of the helicity amplitudes
• Resonances which play a role: S11, P11, P33, D13• Could not fit all the structure functions
simultaneously• Performed several fits to clarify the situation
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Data at Q2<1.45 GeV2
Fit1Fit3Fit2
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Structure functions (ii)
Q2 = 0.4 GeV2
Solid: Fit1Dashed:Fit2Dotted: Fit3
p+n
Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki, Phys. Rev. C 80, 025207 (2009).
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Coupled channels effects
1. Solid Full Fit12. Dashed only N intermediate (in e.m. piece)3. Data from http://clasweb.jlab.org/physicsdb/
Q2 = 0.4 GeV2
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
H. Kamano, B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, arXiv:0909.1129 (2009) (Phys. Rev. C in press)
Study of two pion photoproduction:
• Good description near threshold• Reasonable shape of angular
distributions• Not good description of the total
cross sections of p00 and p+- above 1440 MeV-
Previous (tree level) works include• Meissner (1994)• Gomez Tejedor, Roca,(1993)• Fix et al (2005)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
In progress (~ 2010) EBAC second generation model:
Full Combined (global fit) analysis of: N N, N (W<2 GeV) N N (W<2 GeV) N N (W<2 GeV) N N (W<2 GeV) N N (W<2 GeV)
N* structure extraction *N N (W<2 GeV, Q2<4 GeV2) *N N (W<2 GeV) *N N (W<2 GeV)
WEBPAGE: http://ebac-theory.jlab.org
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
BACKUP
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
EBAC@JLAB
WEBPAGE: http://ebac-theory.jlab.org
MANPOWER:
Leader (ANL/JLAB):• T.-S.H.Lee
Postdocts (JLAB): • H. Kamano• S. Nakamura• K. Tsushima• A. Sibirtsev
Starting date:• 2006
EXTERNAL COLLABORATORS:
• T. Sato, N. Suzuki (Osaka)• A. Matsuyama (Shizuoka)• B. Julia-Diaz (Barcelona)• B. Saghai, J. Durand (Saclay)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Timeline of EBAC results• Full DCC Formalism
A. Matsuyama, T.-S.H. Lee, T. Sato, Phys. Rep. (2007)• Hadronic piece fixed (NN, N)(W<2 GeV)
B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, PRC (2007)J. Durand, B. Julia-Diaz, T.-S.H. Lee, T. Sato, B. Saghai, PRC (2008)
• NN (W<1.6 GeV)B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, LC Smith, PRC (2008)
• NNH. Kamano, B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, PRC (2008)
• Analytic continuation N. Suzuki, T. Sato, T.-S.H. Lee, PRC (2008)
• *N (W<1.6 GeV, Q2<1.5 GeV2)B. Julia-Diaz, H. Kamano, T.-S.H. Lee, A. Matsuyama, T.Sato, , PRC (2009)
• N (W<1.8 GeV)H. Kamano, B. Julia-Diaz, T.-S.H. Lee, A. Matsuyama, T. Sato, PRC (2010)
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
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
σTOT (b)
p
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Structure functions
Q2 = 1.45 GeV2
p0p
Solid: Fit1
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
H. Kamano, B. Julia-Diaz, A. Matsuyama, T.-S.H. Lee, T. Sato, arXiv:0909.1129 (2009), Phys. Rev. C in press
, N* effects
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
PDG *s and N*’s origin
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 >
Most of their properties are extracted from
N N N N
B. Juliá-Díaz, HADRON 2009, Tallahassee, FSU, 2009
Z terms
Z