Upload
camden-marsh
View
54
Download
0
Embed Size (px)
DESCRIPTION
Current Status of EBAC Project. Hiroyuki Kamano Excited Baryon Analysis Center, Jefferson Lab in collaboration with B. Julia-Diaz, T.-S. H. Lee, A. Matsuyama, T. Sato, K. Tsushima. Dynamical Coupled-Channels Analysis @ EBAC. Approaches to determining N-N* form factors. Reaction Data. - PowerPoint PPT Presentation
Citation preview
Current Status of EBAC ProjectCurrent Status of EBAC Project
Hiroyuki KamanoHiroyuki Kamano
Excited Baryon Analysis Center, Jefferson LabExcited Baryon Analysis Center, Jefferson Lab
in collaboration within collaboration with
B. Julia-Diaz, T.-S. H. Lee, A. Matsuyama, B. Julia-Diaz, T.-S. H. Lee, A. Matsuyama,
T. Sato, K. TsushimaT. Sato, K. Tsushima
Approaches to determining N-N* form factors
N-N* form factor
QQCCDD
Lattice QCDHadron Models
Dynamical Coupled-Channels Analysis @ EBACDynamical Coupled-Channels Analysis @ EBAC
Reaction Data
Partial wave (LSJ) amplitude of a b reaction:
Reaction channels:
Potential:
c.c. effect
Coupled-channels model @ EBAC
meson exchangemeson exchange bare N* statebare N* state
Impose minimal number of bare N* state: at present15 of 23 (3* and 4* from PDG)
Impose minimal number of bare N* state: at present15 of 23 (3* and 4* from PDG)
For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007)
Corresponds to theN-N* transition form factor!Corresponds to theN-N* transition form factor!
Through the dynamical reaction processes, N* a bare vertex functions get dressed:
+=
Strategy for analysis @ EBAC
ApplicationApplication
Fit hadronic part of parameters
Fit electro-magneticpart of parameters
FeedbackFeedback
ApplicationApplication
FeedbackFeedback
Pass hadronic parameters
Refit hadronic part of parameters
Refit electro-magneticpart of parameters
Pass hadronic parameters
Application Extract N* N, KY, N
Application
Extract N* N, KY, N
N NJulia-Diaz, Lee, Matsuyama, Sato, PRC76 065201 (2007)
N NJulia-Diaz, Lee, Matsuyama, Sato, Smith, PRC77 045205 (2008)
N NKamano, Julia-Diaz, Lee, Matsuyama, Sato, submitted to PRC
N NDurand, Julia-Diaz, Lee, Saghai, Sato, PRC78 025204 (2008)
N, N NParis, submitted to PRC
Achievements at EBAC
Pion-nucleon elastic scatteringJulia-Diaz, Lee, Matsuyama, Sato, PRC76 065201 (2007)
Five coupled-channels are considered:
Fitted to the SAID N partial wave amplitudes up to 2GeV.
Pion-nucleon elastic scattering
N
Julia-Diaz, Lee, Matsuyama, Sato, PRC76 065201 (2007)
Polarization1340 MeV1340 MeV1440 MeV1440 MeV1540 MeV1540 MeV1680 MeV1680 MeV1760 MeV1760 MeV1860 MeV1860 MeV
Single pion photoproduction reaction
Julia-Diaz, Lee, Matsuyama, Sato, Smith, PRC77 045205 (2008)
Fitted to the data up to 1.65 GeV.
Only N* N bare helicity amps. are varied for the fitting.
Includes 1st and 2nd resonance regionIncludes 1st and 2nd resonance region
0 90 180 0 90 180
0 90 180 0 90 180
-1
1
0
-1
1
0
0
1154 MeV1154 MeV1232 MeV1232 MeV1285 MeV1285 MeV1417 MeV1417 MeV1513 MeV1513 MeV
Julia-Diaz, Lee, Matsuyama, Sato, Smith, PRC77 045205 (2008)
Single pion photoproduction reaction
pi N pi pi N reaction
full result
c.c. effect off
Kamano, Julia-Diaz, Lee, Matsuyama, Sato, submitted to PRC
Parameters used in the calculation are from N N analysis.
full result
phase space
Kamano, Julia-Diaz, Lee, Matsuyama, Sato, submitted to PRC
pi N pi pi N reaction
invariant mass distributions
Data handled with the help of D. Arndt
Key to improving parameters: distributions at low W of
Outlook
Retune parameters using the data of all three reactions. Extends energy region of N N up to 2 GeV
~ end of 2008
Combined analysis of N N, N and N N
*N N (Julia-Diaz, Kamano, Lee, Matsuyama, Sato)
(*)N N (Julia-Diaz, Kamano, Lee, Matsuyama, Sato)
(*)N KY (Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Tsushima)
N N (Durand, Julia-Diaz, Lee, Saghai, Sato)
~ end of 2009
Improved parameters are applied for (& further retuned by)
Extract N-N* electromagnetic transition form factors beyond !!
(Julia-Diaz, Kamano, Lee, Matsuyama, Sato)
W = 1420 MeV W = 1780 MeV
Shape is reasonable. Magnitude overestimates the data.
In most energy,
gamma N pi pi N reaction
invariant mass distributions(preliminary)
Dynamical coupled-channels model for double pion production reactions
Attach appropriate Attach appropriate Green functionsGreen functions ( ) and ( ) and vertex functionsvertex functions ( ) ( )to to NN (on-shell) (on-shell) → → MBMB (off-shell) amplitude (off-shell) amplitude ( )( )
All ingredients already prepared in 2-body calculation !!
All ingredients already prepared in 2-body calculation !!
Dynamical coupled-channels model for double pion production reactions
+
2 2 → → 3 effective potential3 effective potential
= + …+
Not included inNot included inNo new parameter introducedNo new parameter introduced
Dynamical coupled-channels modelfor double pion production reactions
To obtain N → N amplitude, just make replacement below:
where
EBAC @ JLab
Excited Baryon Analysis Center (EBAC) at Jefferson LabExcited Baryon Analysis Center (EBAC) at Jefferson Labhtthttpp://ebac-theor://ebac-theoryy..jjlab.orlab.orgg//
Explore nature of the nucleon resonancesExplore nature of the nucleon resonances from analyzing world data from analyzing world dataof meson production reactions on the nucleon target: of meson production reactions on the nucleon target:
N, γN, γN, γN, γ** N N → → πN, ππN, ηN, ωN, φN, KY, …πN, ππN, ηN, ωN, φN, KY, …
Pole position of N* states on the complex energy plane
Transition form factors of N* states
Search for new N* states
… Closely related to the quark-gluon substructure of N* statesClosely related to the quark-gluon substructure of N* states