1. Progress in the Studies of N
Progress in the Studies of N* Electrocouplings from the CLAS data on p+p-p Electroproduction Data
Victor I. Mokeev
Jefferson Lab
Introduction.
JM model for evaluation of N* electrocouplings in analyzing p+p-p electroproduction.
P11(1440), D13(1520) electrocouplings -ready for publication
Preliminary results on electrocouplings of high lying
N* (M>1.6 GeV)
Conclusions and outlook.

2. The studies of N* electrocouplings: motivation & objectives
Our experimental program seeks to determine
gvNN* transition helicity amplitudes (electrocouplings) at photon virtualities 0.2< Q2<5.0 GeV2 for most of the excited proton states analyzing major meson electroproduction channels combined.
This comprehensive information allows us to:
strong confinement
pin-down active degrees of freedom in N* structure at various distances;
study the non-perturbative strong interactions which are responsible for N* formation and their emergence from QCD;
uniquely access the origin of more than 97% of dressed quark masses, their chromo- and electro- anomalous magnetic moments generated through dynamical chiral symmetry breaking, and explore the origin of confinement .
arXiv: [nucl-th]
quark anom.
electro magn.
moment
ME=0.4 GeV
quark anom. chromo-
magn. moment
N* studies are key to the exploration
of non-perturbative strong
interactions and confinement.

3. Why is p+p-p electroproduction important? Non-resonant amplitudes
p, h, pp,..
p, h, pp,.. γv *
N*,△ + N N’ N’
A3/2, A1/2, S1/2
GM, GE, GC N
Np/Npp channels are the two major contributors in N* excitation region with entirely different non-resonant amplitudes;
consistent results obtained from the analyses of Np and p+p-p channels give confidence that N* electrocouplings can be extracted reliably from these channels
First results on P33(1232), P11(1440),
D13(1520), S11(1535) electrocouplings
from Np CLAS data were published:
I.Aznauryan,V.Burkert, et al. (CLAS Coll.),
PRC 80, (2009).
First results on P11(1440), D13(1520)
electrocouplings from the Npp CLAS
data are ready for publication.

4. The CLAS data on p+p-p differential cross sections and their description within the JM model
G.V.Fedotov et al, PRC 79 (2009),
M.Ripani et al, PRL 91 (2003),
full JM calc.
p+D0 rp
p+F015(1685)
p-D++
2p direct
p+D013(1520)

5. JLAB-MSU meson-baryon model (JM) for Npp electroproduction.
Isobar channels included:
p-D++
3-body processes:
All well established N*s with pD decays and 3/2+(1720) candidate.
Reggeized Born terms with effective FSI & ISI treatment .
Extra pD contact term.
r0p
All well established N*s with rp decays and 3/2+(1720) candidate.
Diffractive ansatz for non-resonant part and r-line shrinkage in N* region.

6. continued 3-body processes: Isobar channels included:
p+D013(1520), p+F015(1685), p-P++33(1640) isobar channels observed for the first time in the CLAS data at W > 1.5 GeV.
(P++33(1640))
(p+)
F015(1685)
Unitarized BW ansatz:
developed based on: I.J.R.Aitchison NP A189 (1972), 417;
provided unitarized resonant amplitude, taking into account the transitions between both diagonal and off-diagonal N* states in the dressed resonance propagator: gv M gv M
N*1
N*1
N*1
N*2 p
diagonal B p
off-diagonal B
D13(1520)↔D13(1700)
P13(1720)↔3/2+(1720)
Consistent with the EBAC-DCC ansatz in on-shell limit
S11(1535)↔S11(1650)

7. continued
Direct 2p production required by unitarity and established for the first time in analysis of the CLAS p+p-p data
Most relevant
at W<1.65 GeV.
Negligible at
W>1.70 GeV
Implementation of direct mechanisms allow us to move beyond isobar
approximation describing p+p-p exclusive channel
JM model : V. Mokeev , V.D.Burkert,T.-S.H.Lee et al., Phys. Rev. C80, (2009).
Recent updates will be presented in the CLAS paper, that is in preparation.

8. Resonant & non-resonant parts of Npp cross sections as determined from the CLAS data fit within the framework of JM model
full cross sections
resonant part
non-resonant part

9. P11(1440) electrocouplings from the CLAS data on Np/Npp electroproduction
Npp preliminary Np
S1/2
I.Aznauryan,V.Burkert, et al., PRC 80, (2009).
Quark models:
I. Aznauryan LC
A1/2
S. Capstick LC
G.Ramalho QM based on relat. cov. approach by F.Gross
MB dressing abs val. (EBAC)
Good agreement between the electrocouplings obtained from the Np and Npp channels: Reliable measurement of the electrocouplings.
The electrocouplings are consistent with P11(1440) structure as a superposition of the contributions from: a) quark core as a first radial excitation of the nucleon as a 3-quark ground state, and b) meson-baryon dressing.

10. Data from exclusive π0 production
Meson-baryon dressing vs Quark core contribution in NΔ Transition Form Factor – GM. EBAC analysis.
One third of G*M at low Q2 is due to contributions from meson–baryon (MB) dressing:
GD = 1
(1+Q2/0.71)2
Data from exclusive π0 production
bare quark core
Within the framework of relativistic QM [B.Julia-Diaz et al., PRC 69, (2004)], the bare-core contribution is very well described by the three-quark component of the wf.
Q2=5GeV2

11. P11(1440) bare mass determined within the framework of EBAC-DCC and DSE approaches.
Pole evolution in P11 pN amplitudes as MB dressing increases from zero to full strength
bare
dressed
EBAC-DCC: N.Suzuki et al.,PRL 104, (2010)
Single bare pole creates three resonant poles in observables : two of them at lower masses correspond to P11(1440), third generates resonance ~1.8 GeV
P11 (1440) bare mass from:
DSE evaluations: C.D.Roberts, et al., arXiv: [nucl-th]
DSE (no contributions from MB dressing)
1.73 GeV
EBAC-DCC bare pole
1.76 GeV
Quark degrees of freedom either
substantial or dominant contributors
to the bare P11(1440) mass

12. MB dressing abs val. (EBAC)
D13(1520) electrocouplings from the CLAS data on Np/Npp electroproduction
A3/2
A1/2
S1/2 Np
M.Giannini/E.Santopinto
hCQM
Npp preliminary
I.Aznauryan,V.Burkert, et al., PRC 80,055203(2009).
of interest for DSE
MB dressing abs val. (EBAC)
reasonable agreement between the results from Np & Npp channels;
substantial contributions from quark core at Q2>2.0 GeV2 and sizable MB cloud
at Q2<1.0 GeV2
The results on A1/2 electrocoupling at Q2>2.0 GeV2 for the first time offer almost direct access to the quark core !

13. High lying resonance electrocouplings
Npp CLAS
preliminary
Δ(1700)D33
Np world
PRELIMINARY
PRELIMINARY
Np CLAS
M.Dugger
et al.,
Q2=0
A3/2
A1/2
S1/2
N(1720)P13
Np PDG
Q2=0
The studies of p+p-p electroproduction are needed for reliable extraction of transition gvNN* electrocouplings for high lying states

14. Conclusions
Good description of all available p+p-p electroproduction data is achieved at W<1.8 GeV and 0.25<Q2<1.5 GeV2, allowing us to isolate resonant contributions, taking into account for restrictions imposed by unitarity. It is vital for the reliable extraction of gvNN* transition electrocouplings .
Electrocouplings of P11(1440) and D13(1520) states for the first time become available from analysis of Npp electroctroproduction and they are ready for publication. The consistent results on electrocouplings of these states, extracted from dominant Np and p+p-p channels, strongly indicate a reliable electrocoupling measure.
Comparison of P11(1440) and D13(1520) electrocouplings with the results of quark models and the EBAC-DCC approach strongly suggests a combined contribution from the external meson-baryon cloud and the internal core of 3 dressed quarks to the structure of these resonances.
gvNN* transition electrocouplings for S11(1650), F15(1685), D33(1700) and P13(1720) states have been determined for the first time from p+p-p electroproduction data at 0.5< Q2<1.5 GeV2
CLAS data on electrocouplings of several N*’s in the mass range M <1.8 GeV for the first time open up an opportunity:
a) to explore the role of meson-baryon and quark degrees of freedom in N* structure ;
b) to study the non-perturbative interactions of dressed quarks that create quark core in N*’s of various quantum numbers.
Successful theoretical interpretation of our data marks an essential step toward a more complete understanding of non-perturbative strong interactions.

15. E.L.Isupov, e1-6 data run analysis,
Outlook
Fully integrated p+p-p electroproduction cross sections from the CLAS data
M.Ripani et al, PRL 91 (2003),
E CLAS experiment
E.L.Isupov, e1-6 data run analysis,
close to completion
Q2=2.2 GeV2
Q2=2.7 GeV2
Q2=3.2 GeV2
VERY PRELIMINARY
Q2=3.8 GeV2
Q2=4.5 GeV2
complete extraction of N* electrocouplings for almost all N*’s with masses <1.8 GeV at 0.5<Q2<1.5 GeV2 from analysis of the data of E experiment ( years);
determine electrocouplings for a major part of N*’s with masses <2.0 GeV at 0.5<Q2<5.0 GeV2 from the data of E experiment and e1-6 run ( years).

16. Back-up

17. Comparison between the CLAS and MAID results

18. Comparison between the CLAS and MAID results

19. New regime in N* excitation at high Q2
EBAC calculations for meson-baryon cloud of low lying N*’s.
the photons of high virtuality penetrate meson-baryon cloud and interact mostly to quark core
data on N* electrocouplings at high Q2 allow us to access quark degrees of freedom, getting rid of meson-baryon cloud.
can be obtained at 5<Q2<10 GeV2 after 12 GeV Upgrade with CLAS12 for majority of N* with masses less then 3.0 GeV
B.Julia-Diaz, T-S.H.Lee, et.al, Phys. Rev. C77, (2008).

20. High lying resonance electrocouplings from Npp CLAS data analysis
N(1685)F15
The amplitudes of
unitarized BW ansatz
A1/2
S1/2 gv M
N*1
N*1 p
diagonal B
N(1650)S11 gv M
N*1
N*2
Unitarization of full BW amplitudes was achieved accounting for all interactions between N*’s in dressed resonant propagator p
off-diagonal B

21. V.D. Burkert et al., Phys. Rev. C76, 035204 (2003).
Electrocouplings of [70,1-] SUsf(6)-plet states from Np/Npp CLAS data and their description in SQTM approach
D13(1520)
SU(6) spin-flavor symmetry for quark binding interactions
Dominant contribution from single quark transition operator:
D13(1520)
World data before CLAS measurements on transverse electrocouplings of D13(1520) and S11(1535) states (the areas between solid lines) allowed us to predict transverse electrocouplings for others [70,1-] states (the areas between solid lines on the next slide), utilizing SU(6) symmetry relations.
S11(1535)
V.D. Burkert et al., Phys. Rev. C76, (2003).

22. relevance of quark degrees of freedom;
Electrocouplings of [70,1-] SUsf(6)-plet states from Np/Npp CLAS data and their description in SQTM approach
SQTM predictions are consistent with major features in the CLAS data, offering an indication for:
relevance of quark degrees of freedom;
substantial contribution to quark binding from interactions that poses SU(6) spin-flavor symmetry;
considerable contribution from single quark transition operator to N-N* transition e.m. current.
S31(1620)
A1/2
D33(1700)
D33(1700)
S11(1650)
A3/2