dynamical coupled-channels approach to meson production reactions in the n* region and its...
DESCRIPTION
Objectives and goals: Through the comprehensive analysis of world data of N, N, N(e,e’) reactions, Determine N* spectrum (pole masses) Extract N* form factors (e.g., N-N* e.m. transition form factors) Provide reaction mechanism information necessary for interpreting N* spectrum, structures and dynamical origins Dynamical coupled-channels analysis of meson production reactions Spectrum, structure,… of N* states QCDQCDQCDQCD Lattice QCDHadron Models Analysis Based on Reaction Theory Reaction Data H. Kamano (RCNP), T.-S. H. Lee (ANL), S. Nakamura (JLab), T. Sato (Osaka U./KEK) B. Julia-Diaz (Barcelona U.), A. Matsuyama (Shizuoka U.), N. Suzuki (Osaka U.)TRANSCRIPT
Dynamical coupled-channels approach to meson production reactions in the N* region and its application to neutrino-nucleon/nucleus
reactions
Hiroyuki Kamano(RCNP, Osaka Univ.)
Seminar at J-PARC, March 19, 2012
Since the late 90s, huge amount of high precision data of meson photo-production reactions on the nucleon target has been reported from electron/photon beam facilities.
JLab, MAMI, ELSA, GRAAL, LEPS/SPring-8, …
Experimental developments
E. Pasyuk’s talk at Hall-B/EBAC meeting
Opens a great opportunity to make quantitative study of the N* states !!
Objectives and goals:
Through the comprehensive analysis of world data of pN, gN, N(e,e’) reactions,
Determine N* spectrum (pole masses)
Extract N* form factors
(e.g., N-N* e.m. transition form factors)
Provide reaction mechanism information necessary for interpreting N* spectrum, structures and dynamical origins
Dynamical coupled-channels analysis ofmeson production reactions
Spectrum, structure,…of N* states
QCD
Lattice QCDHadron Models
Analysis Based on Reaction Theory
Reaction Data
H. Kamano (RCNP), T.-S. H. Lee (ANL), S. Nakamura (JLab), T. Sato (Osaka U./KEK)B. Julia-Diaz (Barcelona U.), A. Matsuyama (Shizuoka U.), N. Suzuki (Osaka U.)
A. Matsuyama, T. Sato, T.-S.H. Lee Phys. Rep. 439 (2007) 193
Dynamical coupled-channels model of meson production reactions
Singular!
a
a
Dynamical coupled-channels model for meson production reactions
Meson production dataN* spectrum, structure, …
Reaction dynamics
Hadronic amplitudes in the DCC model
+
Non-resonant amp. Rsonant amp.
M
B B’
M’
B B’
M M’
Amplitudes of two-body meson-baryon reactions
For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007)
Reaction channels:
Hadronic amplitudes in the DCC modelFor details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007)
+
Non-resonant amp. Rsonant amp.
M
B B’
M’
B B’
M M’
+ +
+
=
=
+ …
M’’
B’’p, r, s, w,..
N N, D
s-channel u-channel
t-channel contact
Dp
N p
p
DDNp
r, s
Exchangepotentials
“Z-diagrams”
~ 150 Feynman diagrams
Meson-Baryon Green functions
Stable channels
N
D D
ppp
r, s
N N
Quasi 2-body channelsp
p
Produce 2-body and 3-body ppN cuts required by the unitarity !!
r, s
Hadronic amplitudes in the DCC modelFor details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007)
+
Non-resonant amp. Rsonant amp.
M
B B’
M’
B B’
M M’
+ +
+
=
=
+ …
M’’
B’’
Hadronic amplitudes in the DCC modelFor details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007)
+
Non-resonant amp. Rsonant amp.
M
B B’
M’
B B’
M M’
+=
Dressed N*-MB vertex
Meson cloudBare vertexBare
propagator(Bare mass)
Self energy
= +
Dressed N* propagatorNon-resonant amp.
Effects of rescattering processes (reaction dynamics) are included consistently with the unitarity of S-matrix.
Electromagnetic amplitudes in the DCC model
+
Non-resonant amp. Rsonant amp.
g
B B’
M’
B B’
M’
E.M. current interactions are treated perturbatively.
For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007)
g
+=
+=Dressed gN N* vertex
Bare vertex
Rescattering effect
Rescattering effect
DCC analysis of meson production reactions (current status)
pp pN
gp pN
p-p hn
gp hp
pp KL, KS
gp KL, KS
2006 ~ 2009
5 channels (pN,hN,pD,rN,sN)
< 2 GeV
< 1.6 GeV
< 2 GeV
―
―
―
2010 ~ 2012
7 channels (pN,hN,pD,rN,sN,KL,KS)
< 2.1 GeV
< 2 GeV
< 2 GeV
< 2 GeV
< 2.2 GeV
< 2.2 GeV
# of coupled channels
Fully combined analysis of gN , pN pN , hN , KL, KS reactions !!
Kamano, Nakamura, Lee, Sato(2012)
Analysis Database
Pion-inducedreactions (purely strong reactions)
Photo-productionreactions
~ 28,000 data points to fit
Partial wave amplitudes of pi N scattering
Kamano, Nakamura, Lee, Sato2012
Previous model (fitted to pN pN data only)[PRC76 065201 (2007)]
Real part
Imaginary part
Pion-nucleon elastic scattering
Target polarization
1234 MeV
1449 MeV
1678 MeV
1900 MeV
Angular distribution
Kamano, Nakamura, Lee, Sato, 2012
pi N MB reactionsKamano, Nakamura, Lee, Sato, 2012
1732 MeV
1845 MeV
1985 MeV
2031 MeV
1757 MeV
1879 MeV
1966 MeV
2059 MeV
1792 MeV
1879 MeV
1966 MeV
2059 MeV
Data handled with the help of R. Arndt
pi N pi pi N reaction
Parameters used in the calculation are from pN pN analysis.
Kamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC79 025206 (2009)
Full result
Phase spaceFull result
W (GeV)
s (m
b)
C. C. effect off
Single pion photoproduction
Kamano, Nakamura, Lee, Sato, 2012 Previous model (fitted to gN pN data up to 1.6 GeV) [PRC77 045205 (2008)]
Angular distribution Photon asymmetry
1137 MeV 1232 MeV 1334 MeV
1462 MeV 1527 MeV 1617 MeV
1729 MeV 1834 MeV 1958 MeV
Kamano, Nakamura, Lee, Sato, 2012
1137 MeV 1232 MeV 1334 MeV
1462 MeV 1527 MeV 1617 MeV
1729 MeV 1834 MeV 1958 MeV
Kamano, Nakamura, Lee, Sato 2012
Kamano, Nakamura, Lee, Sato 2012
Kamano, Nakamura, Lee, Sato 2012
Kamano, Nakamura, Lee, Sato 2012
Kamano, Nakamura, Lee, Sato 2012
Kamano, Nakamura, Lee, Sato 2012
Double pion photoproductionKamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC80 065203 (2009)
Parameters used in the calculation are from pN pN & gN pN analyses.
Good description near threshold
Reasonable shape of invariant mass distributions
Above 1.5 GeV, the total cross sections of pp0p0 and pp+p-
overestimate the data.
Single pion electroproduction (Q2 > 0)
Fit to the structure function data (~ 20000) from CLAS
Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki, PRC80 025207 (2009)
p (e,e’ p0) p
W < 1.6 GeVQ2 < 1.5 (GeV/c)2
is determinedat each Q2.
N*N
g (q2 = -Q2)q
N-N* e.m. transitionform factor
N, N*
Meson cloud effect in gamma N N* form factors
GM(Q2) for g N D (1232) transition
Note:Most of the available static hadron models give GM(Q2) close to “Bare” form factor.
Full
Bare
How to extend the DCC model to neutrino reactions
+
Non-resonant amp. Rsonant amp.
g
B B’
M’
B B’
M’
Just replace E.M. current by vector and axial currents.
g
+=
+=Dressed gN N* vertex
Bare vertex
Rescattering effect
V, A V, A
Dressed VN or AN N* vertex
V, A V, A
V, A V, A V, A
How to extend the DCC model to neutrino reactions
V, A
V, A
Vector part Axial part
What we need to do:
Ready for neutrino reaction(We can get all isospin components simply by isospin rotation.)
Evaluation ofg neutron N* verticesfor I = ½ N* states
For N*s except D(1232), as a first step, we evaluateA N N* vertices frompNN* couplings by making use of PCAC.
Construct AN MB potentialfor MB = pD, rN, sN, KL, KS(We already have the potentialfor MB = pN case.)