Transcript Dynamical Coupled-Channels Approach for Single- and Double-Pion Electroproductions: Status and Plans Hiroyuki Kamano Research Center for Nuclear Physics (RCNP) Osaka University EmNN*2012 Workshop @ USC, USA,

Dynamical Coupled-Channels Approach for
Single- and Double-Pion Electroproductions:
Status and Plans
Hiroyuki Kamano
Research Center for Nuclear Physics (RCNP)
Osaka University
EmNN*2012 Workshop @ USC, USA, August 13-15, 2012
Outline
1. Background and motivation for N* spectroscopy
2. ANL-Osaka Dynamical Coupled-Channels (DCC)
approach for N* spectroscopy
3. Status and plans for single- and double-pion
electroproduction reactions
4. Related hadron physics program at J-PARC
Background and motivation for
N* spectroscopy
(1 / 4)
N* spectroscopy :
Physics of broad & overlapping resonances
N* : 1440, 1520, 1535, 1650, 1675, 1680, ...
Δ (1232)
D : 1600, 1620, 1700, 1750, 1900, …
 Width: a few hundred MeV.
 Width: ~10 keV to ~ 10 MeV
 Resonances are highly overlapping
in energy except D(1232).
 Each resonance peak is clearly separated.
Hadron spectrum and reaction dynamics
 Various static hadron models have been proposed to calculate
hadron spectrum and form factors.
 Quark models, Bag models, Dyson-Schwinger approaches, Holographic QCD,…
 Excited hadrons are treated as stable particles.  The resulting masses are real.
 In reality, excited hadrons are “unstable” and can exist
only as resonance states in hadron reactions.
“molecule-like” states
“Mass” becomes complex !!
 “pole mass”
u
u
d
core (bare state) + meson cloud
What is the role of reaction dynamics in interpreting
the hadron spectrum,
structures,
dynamical origins ??
Constituent
quarkand
model
N*
meson cloud
bare state
ANL-Osaka Dynamical Coupled-Channels (DCC)
approach for N* spectroscopy
(2 / 4)
ANL-Osaka Dynamical Coupled-Channels
Approach for N* Spectroscopy
Reaction Data
Objectives and goals:
Through the comprehensive analysis
of world data of pN, gN, N(e,e’) reactions,
Analysis Based on Reaction Theory
 Determine N* spectrum (pole masses)
 Extract N* form factors
Spectrum, structure,…
“Dynamical of
coupled-channels
N* states
(e.g., N-N* e.m. transition form factors)
model of meson production reactions”
A. Matsuyama, T. Sato,
T.-S.H. Lee
Phys. Rep.
439 (2007)information
193
 Provide
reaction
mechanism
Hadron Models
Lattice QCD
necessary for interpreting N* spectrum,
structures and dynamical origins
QCD
Dynamical coupled-channels (DCC) model for
meson production reactions
For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007)
 Partial wave (LSJ)
amplitudes of a 
b reaction:
u-channel
s-channel
t-channel
contact
p, r, s, w,..
Physical N*s will
of the two pictures:
N be a “mixture”
N, D
p
r, s
coupled-channels effect
p
D
baryon
N
 Reaction channels: p
N
p
 Meson-Baryon
Green Dfunctions
D
core Z-diagrams
Can be related to hadron
states of the static
hadron models (quark models, DSE, etc.)
Quasi 2-body channels
excluding
meson-baryon continuum.
Bare N* states
meson
Stable channels
N*bare
 Transition Potentials:
meson potentials
cloud
Exchange
N
D
p
D
r, s
p
p
Exchange potentials
p
p
Z-diagrams
r, s
N
N
bare N* states
DCC analysis (2006-2009)
gN, pN, hN, pD, rN, sN coupled-channels
calculations were performed.
Hadronic part
pNpN
: Analyzed to construct a hadronic part of the model up to W = 2 GeV
Julia-Diaz, Lee, Matsuyama, Sato, PRC76 065201 (2007)
pNhN
: Analyzed to construct a hadronic part of the model up to W = 2 GeV
Durand, Julia-Diaz, Lee, Saghai, Sato, PRC78 025204 (2008)
pNppN
: Fully dynamical coupled-channels calculation up to W = 2 GeV
Kamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC79 025206 (2009)
Electromagnetic part
 g(*) N  p N
: Analyzed to construct a E.M. part of the model up to W = 1.6 GeV and Q2 = 1.5 GeV2
(photoproduction) Julia-Diaz, Lee, Matsuyama, Sato, Smith, PRC77 045205 (2008)
(electroproduction) Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki, PRC80 025207 (2009)
 g NppN
: Fully dynamical coupled-channels calculation up to W = 1.5 GeV
Kamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC80 065203 (2009)
Extraction of N* parameters
 Extraction of N* pole positions & new interpretation on the dynamical origin of P11 resonances
Suzuki, Julia-Diaz, Kamano, Lee, Matsuyama, Sato, PRL104 065203 (2010)
 Stability and model dependence of P11 resonance poles extracted from pi N  pi N data
Kamano, Nakamura, Lee, Sato, PRC81 065207 (2010)
 Extraction of gN  N* electromagnetic transition form factors
Suzuki, Sato, Lee, PRC79 025205 (2009); PRC82 045206 (2010)
Dynamical origin of nucleon resonances
Suzuki, Julia-Diaz, Kamano, Lee, Matsuyama, Sato, PRL104 065203 (2010)
Pole positions and dynamical origin of P11 resonances
pole A: pD unphys. sheet
pole B: pD phys. sheet
Corresponds to hadron states
from static hadron models
Multi-channel reactions can
Double-pole nature of the Roper is found
from completely different approaches:
generate many resonancealso
poles
from a single bare state !!
Eden, Taylor, Phys. Rev. 133 B1575 (1964)
For evidences in hadron and nuclear physics, see
e.g., in Morgan and Pennington, PRL59 2818 (1987)
N-N* transition form factors at
resonance poles
Extracted from analyzing the p(e,e’p)N data from CLAS
Nucleon - 1st D13 e.m. transition form factors
Coupling to meson-baryon continuum states
makes N* form factors complex !!
Fundamental nature of resonant particles
(decaying
states)
Real part
Imaginary part
Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki PRC80 025207 (2009)
Suzuki, Sato, Lee, PRC82 045206 (2010)
Dynamical coupled-channels (DCC) analysis
Fully combined analysis of pN , gN  pN , hN , KL, KS reactions !!
(more than 20,000 data points to fit)
2006 - 2009
2010 - 2012
6 channels
8 channels
(gN,pN,hN,pD,rN,sN)
(gN,pN,hN,pD,rN,sN,KL,KS)
 pp  pN
< 2 GeV
< 2.1 GeV
 gp  pN
< 1.6 GeV
< 2 GeV
 pp  hN
< 2 GeV
< 2 GeV
 gp  hp
―
< 2 GeV
 pp  KL, KS
―
< 2.2 GeV
 gp  K+L, KS
―
< 2.2 GeV
 # of channels
Kamano, Nakamura, Lee, Sato
(2012)
Partial wave amplitudes of pi N scattering
Real part
8ch DCC-analysis
(Kamano, Nakamura, Lee, Sato
2012)
6ch DCC-analysis
(fitted to pN  pN data only)
[PRC76 065201 (2007)]
Imaginary part
Partial wave amplitudes of pi N scattering
Real part
8ch DCC-analysis
(Kamano, Nakamura, Lee, Sato
2012)
6ch DCC-analysis
(fitted to pN  pN data only)
[PRC76 065201 (2007)]
Imaginary part
π- p  ηn reactions
Kamano, Nakamura, Lee, Sato, 2012
 Analyzed data up to W = 2 GeV.
 p- p  h n data are selected
according to Durand et al. PRC78 025204.
πN  KY reactions (1/2)
Kamano, Nakamura, Lee, Sato, 2012
π- p  K0Λ
π-p  K0Σ0
π+p  K+Σ+
πN  KY reactions (2/2)
π-
p
K0Λ
Kamano, Nakamura, Lee, Sato, 2012
π-p  K0Σ0
π+p  K+Σ+
γp  πN reactions(1/2)
γp  π0p
γp  π+n
Kamano, Nakamura, Lee, Sato, 2012
γp  πN reactions(2/2)
Kamano, Nakamura, Lee, Sato, 2012
γp  π0p
γp  π+n
γp  ηp reaction
Kamano, Nakamura, Lee, Sato, 2012
γp  K+Σ0, K0Σ+ reactions
γp  K+Σ0
Kamano, Nakamura, Lee, Sato, 2012
γp  K0Σ+
γp  K+Λ reaction (1/4)
Kamano, Nakamura, Lee, Sato, 2012
γp  K+Λ reaction (2/4)
Kamano, Nakamura, Lee, Sato, 2012
γp  K+Λ reaction (3/4)
Kamano, Nakamura, Lee, Sato, 2012
γp  K+Λ reaction (4/4)
Kamano, Nakamura, Lee, Sato, 2012
Status and plans for single- and double-pion
electroproduction rections
(3 / 4)
Status and plans for analysis of
electroproduction reactions
(Q2 = 0 point)
 γp  πN
 γp  ππN
6-channel (2006-2009)
8-channel (2010-2012)
W < 1.6 GeV
(the data analyzed)
W < 2 GeV
(the data analyzed)
W < 1.6 GeV
(cross sections predicted)
VERY preliminary
Not yet done
results available
(nonzero Q2)
 ep  e’πN
W < 1.6 GeV, Q2 < 1.5 (GeV/c)2
(the data analyzed)
 ep  e’ππN
[Plan 1]: After completing 8-ch analysis,
immediately proceed to the analysis
of CLAS p(e,eπ)N data and extract
N-N* e.m. transition form factors
up to Q2 ~ 4 (GeV/c)2.
Not yet done
Not yet done
[Plan 2]: After Plan 1, we can give
prediction for p(e,eππ)N cross sections.
[Combined analysis of p(e,eπ)N and
p(e,eππ)N will be a long term project.]
γp  ππN calculation with 8-ch. DCC model
Prediction for γp  ππ N total cross sections (not yet included in the fit)
VERY PRELIMINARY !!
8-ch. DCC Full
(Kamano, Nakamura, Lee, Sato 2012)
8-ch. DCC Nonresonant only
6-ch. DCC Full [PRC80 065203 (2010)]
6-ch. DCC Nonresonant only
Related hadron physics program at J-PARC
(4 / 4)
Hadron physics program at J-PARC
WG on “Hadron physics with high-momentum beam line at J-PARC”
Currently J-PARC has high-momentum proton (< 30 GeV/c) and pion
(~ 15 GeV/c) beams.
 Now considered as one of the highest priority projects at KEK/J-PARC
from April 2013.
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Hadron properties in nuclear medium
pQCD, partonic structure of nucleon and nuclei
Charmed-hadron physics
Exotic hadrons and nuclei
N* physics (N*, Δ*, ...)
High-energy spin physics
Short-range NN correlations
Transition from hadron to quark degrees of freedom
Exclusive processes (GPD, quark counting, ...)
Quark/hadron interactions in nuclear medium (parton-energy loss, color
transparency)
 J/ψ production mechanisms and its interactions in nuclear medium
 Pion distribution amplitude, hadron-transition distribution amplitudes
 Intrinsic charm and strange
… AND MORE TO COME!!
Hadron physics program at J-PARC
 Measurement of πN  ππN & KY in high-mass N* region
(K. Hicks, K. Imai et al.)
 πN  ππN: “Critical missing piece” in N* spectroscopy.
 There is NO practical data that can be used for partial wave analysis
above W > 1.5 GeV.
 Above W > 1.5 GeV, πN  ππN becomes the dominant process of
the πN reactions.
 Most of the N*s decay dominantly to the ππN channel.
The current N* mass spectrum might receive significant modifications
and even new N* states might be discovered by the combined analysis
including this new πN  ππN data !!
The idea originates from “US-Japan Joint
Workshop on Meson Production Reactions at
Jefferson Lab and J-PARC” Hawaii, Oct. 2009.
Hadron physics program at J-PARC
 Measurement of forward p(π,ρ)X, p(π, K*)X reactions
(T. Ishikawa, T. Nakano et al.)
ρ (fast)
high-p π
virtual π
p
Q2
N*, Δ* (slow)
 Can be used for extracting
N-N* axial transition form factors
Crucial for constructing reliable neutrino-nucleon/nucleus
reaction models in resonance and DIS region.
 Collaboration@J-PARC Branch of KEK Theory Center
[Y. Hayato, M. Hirai, H. Kamano, S. Kumano, S. Nakamura,
K. Saito, M. Sakuda, T. Sato]
(http://j-parc-th.kek.jp/html/English/e-index.html)
high-p π
virtual K
p
K* (fast)
Q2
Y* (slow)
 Can access to Λ(1405) region
below KN threshold.
 Could be used for extracting
strangeness changing axial
form factors.
Summary
Summary
2006 - 2009
2010 - 2012
6 channels
8 channels
(gN,pN,hN,pD,rN,sN)
(gN,pN,hN,pD,rN,sN,KL,KS)
 pp  pN
< 2 GeV
< 2.1 GeV
 gp  pN
< 1.6 GeV
< 2 GeV
 pp  hN
< 2 GeV
< 2 GeV
 gp  hp
―
 pp  KL, KS
―
< 2.2 GeV
 gp  K+L, KS
―
< 2.2 GeV
 # of channels
;
< 2 GeV
With the new 8-channels model, nucleon resonance parameters
(mass spectrum, decay widths, etc.) are being investigated.
(As presented in T. Sato’s talk)
 After completing the combined analysis of πp, γp  πN, ηN, KΛ, KΣ reactions,
immediately proceed to the analysis of CLAS p(e,eπ)N data and extract N-N* e.m.
transition form factors up to Q2 ~ 4 (GeV/c)2.
 Combined analysis of p(e,eπ)N and p(e,eππ)N is considered as a long term project in future.
[Combined analysis of p(e,e’π)N, p(e,e’η)p, p(e,e’K)Y could be done quickly.]
back up
Phenomenological prescriptions of constructing
conserved-current matrix elements
As commonly done in practical calculations in nuclear and particle physics,
currently we take a phenomenological prescription to construct conserved
current matrix elements [T. Sato, T.-S. H. Lee, PRC60 055201 (2001)]:
: Full e.m. current matrix elements obtained by solving DCC equations
: photon momentum
: an arbitrary four vector
 A similar prescription is applied, e.g., in Kamalov and Yang, PRL83, 4494 (1999).
 There are also other prescriptions that enable practical calculations satisfying
current conservation or WT identity:
 Gross and Riska, PRC36, 1928 (1987)
 Ohta, PRC40, 1335 (1989)
 Haberzettl, Nakayama, and Krewald, PRC74, 045202 (2006).
Experimental developments
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, …
Opens a great
opportunity to make
quantitative study of
the N* states !!
E. Pasyuk’s talk at Hall-B/EBAC meeting
N* states and PDG *s
Arndt, Briscoe, Strakovsky, Workman PRC 74 045205 (2006)
?
?
Most of the N*s were extracted from
?
?
?
From PDG 2010
Need comprehensive analysis of
channels !!
Width of N* resonances
(Current status)
Kamano, Nakamura, Lee, Sato, 2012
Note: Some freedom exists on the definition of partial width
from the residue of the amplitudes.
Spectrum of N* resonances
(Current status)
Real parts of N* pole values
PDG
Ours
PDG 4*
PDG 3*
Kamano, Nakamura, Lee, Sato, 2012
L2I 2J
N* with 3*, 4*
18
N* with 1*, 2*
5
Ours
16
γp  πN reactions
Angular distribution
Photon asymmetry
1334 MeV
1137 MeV
1232 MeV
1462 MeV
1527 MeV
1729 MeV
1834 MeV
1137 MeV
1232 MeV
1334 MeV
1462 MeV
1527 MeV
1617 MeV
1729 MeV
1834 MeV
1958 MeV
1617 MeV
1958 MeV
8ch DCC-analysis
Kamano, Nakamura, Lee, Sato 2012
6ch DCC-analysis [PRC77 045205 (2008)]
(fitted to gN  pN data up to 1.6 GeV)
Single pion electroproduction (Q2 > 0)
Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki, PRC80 025207 (2009)
Fit to the structure function data (~ 20000) from CLAS
p (e,e’ p0) p
W < 1.6 GeV
Q2 < 1.5 (GeV/c)2
is determined
at each Q2.
g
q
N
(q2 = -Q2)
N*
N-N* e.m. transition
form factor
Single pion electroproduction (Q2 > 0)
Julia-Diaz, Kamano, Lee, Matsuyama, Sato, Suzuki, PRC80 025207 (2009)
Five-fold differential cross sections at Q2 = 0.4 (GeV/c)2
p (e,e’ p0) p
p (e,e’ p+) n
pi N  pi pi N reaction
Kamano, Julia-Diaz, Lee, Matsuyama, Sato, PRC79 025206 (2009)
s (mb)
Parameters used in the calculation are from pN  pN analysis.
W (GeV)
Full result
C. C. effect off
Data handled with
the help of R. Arndt
Full result
Phase space