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Nucleon Resonance Structure from the CLAS@JLAB Meson Electroproduction Data

V.I. Mokeev, Jefferson Lab and SINP MSU, on behalf of the CLAS Collaboration

16th Lomonosov Conference on Elementary Particle Physics
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Weak and Electromagnetic Interactions as the Tools for Exploration of the Ground and Excited Nucleon State Structure
Weak interaction: neutrino-nucleon scattering:


N

l±,0
W, Z N N



l±,0
W, Z X

Electromagnetic interaction: electron (muon)-nucleon scattering:

e

-

e
v

-'

e

-

e
v

-'

e

-'

e


-

N

v

N

N

X

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


N*-States in Inclusive Electron Scattering
Total virtual photon cross sections
F. Foster and G.Hughes, Rep. Progr. Phys. 46, 1445 (1983). Q2, 1000 GeV2

The peak content
P33(1232) P11(1440), D13(1520), S11(1535)., S31(1620) S11(1650), F15(1685), D33(1700), P11(1710), P13(1720). 3/2+(1720).

What we knew 30 years ago:

0.1 100 , mcbn 0.5 1.3 2.3 3.3 5.0 6.0

·three resonant peaks. ·different Q2-evolution of these peaks ·different structure of different N*states.


10

1.2

1.5

2.0 W, GeV

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Extraction of vNN* Electrocouplings from the Data on Exclusive Meson Electroproduction off Protons
e' e Resonant amplitudes

, , ,..

Non-resonant amplitudes

, , ,..


N

v

N*,

*
N'

+
N N'
See details in: I.G.Aznauryan and V.D.Burkert, Progr. Part. Nucl. Phys. 67, 1 (2012).

·A1/2(Q2), A3/2(Q2), S1/2(Q2) or ·G1(Q2), G2(Q2), G3(Q2) or 2), G (Q2), G (Q2) ·GM(Q E C

· Separation of resonant/non-resonant contributions within the framework of reaction models; Breit-Wigner ansatz for parameterization of resonant amplitudes; fit of resonance electrocouplings and hadronic parameters to the data. Consistent results on vNN* electrocouplings from different meson electroproduction channels and different analysis approaches demonstrate reliable extraction of N* parameters.
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


CEBAF Large Acceptance Spectrometer
Torus magnet 6 superconducting coils Liquid D2 (H2)target + start counter; e minitorus Drift chambers argon/CO2 gas, 35,000 cells Gas Cherenkov counters e/ separation, 216 PMTs Large angle calorimeters Lead/scintillator, 512 PMTs

Timeofflight counters plastic scintillators, 684 PMTs

Electromagnetic calorimeters Lead/scintillator, 1296 PMTs

The unique combination of the CEBAF continuous electron beam with the best worldwide parameters and the CLAS detector of nearly 4 acceptance makes Hall-B@JLAB the most versatile facility operational worldwide for exploration of the nucleon structure.
V.I.Mokeev User Group kshop Peniscola, Spain, V.I.Mokeev, NSTAR 2013 WorMeeting June 18 2008 May 27-30, 2013


Motivation and Objectives for the Studies of the vpN*-Electrocouplings in Exclusive Meson Electroproduction The CLAS experimental program seeks to determine vpN* electrocouplings at photon virtualities up to 5.0 GeV2 for most of the excited proton states through analyzing major meson electroproduction channels independently and in global multi- channel analyses. This information is needed to study the evolution of relevant degrees of freedom in N* structure with distance and to access the non-perturbative strong interaction which generates N* states as bound systems of quarks and gluons: I. G. Aznauryuan et al., Int. J. Mod. Phys. E22, 133015 (2013). The non-perturbative strong interaction represents the most important part of the Standard Model that we have yet to explore.

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Non-Perturbatively Generated Effective Degrees of Freedom in the Ground and Excited Nucleon State Structure Emergence of dressed constituent quarks (C.Q.) and gluons:

dressed quark

bare quark

dressing kernel

dressed gluon

bare gluon

dressing kernel

·Dressed quarks and gluons acquire dynamical, momentum dependent structure and masses in the regime of large s which is relevant for the N* formation. ·Their non-perturbative interactions are very complex and far beyond the scope of pQCD.
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Resonance Electrocouplings as a Window into Non-perturbative Strong Interaction quark/gluon confinement The N/N* generation:
C.Q. C.Q. C.Q.

Exploration of the N/N* state structure addresses the most fundamental questions: ·Nature of >98 % of the hadron mass in Universe, which is generated non-perturbatively . The Higgs mechanism is almost irrelevant for the light hadron mass generation. ·How quark-gluon confinement in baryons emerges from the QCD.

Available/future data on elastic form factors and vpN*-electrocouplings from CLAS/CLAS12 detectors offer the access to the dressed quark mass function in the range of momenta p up to 1.15 GeV.

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


The CLAS Data on +-p Differential Cross Sections and their Description within the Framework of Meson-Baryon Reaction Model JM
G.V.Fedotov et al, PRC 79 (2009), 015204 1.30
full JM calc. -++

+0 2 direct

p +D
0 13

+F015(1680) (1520)

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


The JM Model for Analysis of the +-p Electroproduction
Major objectives: extraction of vNN* electrocouplings and the , p decay widths.



-

+ =

-/+
++/0 (1232)P33, N0 (1520)D13, ++ (1600)P33, N0(1680)F15

p

p'

p


p'


+ p p'

- +

-, +, ... +, -, ...
p',p', ...

·six meson-baryon channels and direct +-p production. ·N* contribute to and p channels only.

+ p

·unitarized Breit-Wigner ansatz for resonant amplitudes.

· Developed in Collaboration between JLAB and SINP at MSU. · Only available worldwide approach for extraction of resonance parameters from the +-p electroproduction data.
V.I.Mokeev User Group kshop Peniscola, Spain, V.I.Mokeev, NSTAR 2013 WorMeeting June 18 2008 May 27-30, 2013

10


N Magnetic Transition Form Factor and the Components of the N* Structure
Magnetic Dipole Form Factor
CLAS Hall A Hall C MAMI Bates

The mechanisms of the meson-baryon dressing

MesonBaryon cloud

bare quark core

T. Sato and T-S. H. Lee, PRC 63, 055201 (2001).

Successful description of N transition form factors was achieved taking into account the contributions from the external mesonbaryon cloud and the internal core of three dressed constituent quarks.
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Quark Core Contribution to N Magnetic Form Factors from the QCD Lagrangian Quark core contribution from DSEQCD:J.Segovia, et al., arXiv:1305.0292[nucl-th].
G*M (Jones-Scardon)

Q2/m contact interaction. contact interaction & quark anomalous magn. moment. projection for quark running mass. bare G*M inferred from exp. data within Argonne-Osaka c.c. approach.

2

Promising potential of DSEQCD approaches in describing the quark core contribution from the first principles of QCD.

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


The P11(1440) and D13(1520) Structure from the CLAS Electrocoupling Data
CLAS data: +-p N 2012 2009
-1/2

80 60

20 0

D13(1520) A1/2

40 20 0

P11 (1440) Quark core from the quark models:
I.G.Aznauryan, PRC 76, 025212 (2007). S.Capstick and B.D.Keister, PRD 51, 3598 (1995).

-20 -40 -60 -80 0 1 2 2 Q GeV
2

P11(1440) A1/2 A1/2
3 4

A1/2*1000 GeV-1/2

A1/2*1000 GeV

+-p prelim.

-20 -40 -60 -80

-100 -120 0

Quark core: E.Santopinto, M.Giannini PRC 86, 065202 (2012).
1 2

Q GeV

2

2

3

4

5

Meson-Baryon dressing: (absolute values)
B,Julia-Diaz et al., PRC 77, 045205 (2008).

· Consistent values of P11(1440) electrocouplings determined in independent analyses of N and +-p exclusive channels strongly support reliable electrocoupling extraction.

· The physics analyses of these results revealed the P11(1440) and D13(1520) structure as a combined contribution of: a) quark core as a first radial and orbital L=1 excitations of the 3quarks, respectively and b) meson-baryon dressing.
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


High-Lying Resonance Electrocouplings from the +-p CLAS Data Analysis
1/2

V.D.Burkert, et al., PRC 67, 035204 (2003).

N CLAS
preliminary

A1/2*1000 GeV

N world

N Q2=0,
CLAS M.Dugger, et al., PRC 79,065206 (2009).

120 100 80 60 40 20

(1700)D

33

BF(N): 80-90%

A

1/2

A3/2*1000 GeV

+-p electroproduction channel provided first preliminary results on S31(1620), S11(1650), F15(1685), D33(1700) , and P13(1720) electrocouplings of a good accuracy.

0 0
-1/2

0.2

0.4

0.6

0.8

1

Q GeV

1.2 2

1.4

2

120 100 80 60 40

A

3/2

SQTM approach: I.G. Aznauryan and V.D. Burkert, Progr. Nucl. Part. Phys. 67, 1 (2012).

20 0 -20 0 0.2 0.4 0.6 0.8 1 1.2 1.4

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013

Q GeV

2

2


Conclusions and Outlook
· High quality meson electroproduction data from the CLAS detector allowed us to determine electrocouplings of the most excited states in the mass range of W<1.8 GeV from analyses of N and N and N exclusive electroproduction off protons for the first time. Consistent values of vNN* electrocouplings from independent analyses of N/N and N/N channels confirmed reliable extraction of these fundamental quantities. Analyses of vNN* electrocouplings revealed the N*-structure as internal core of three constituent quarks surrounded by external meson-baryon cloud. Resonances of different quantum numbers provided complementary information on the N* structure. The data on electrocouplings of all prominent N*-states are needed. Electrocouplings of most N*-states in mass range up to 2.0 GeV will be determined in few years from analyses of N electroproduction at photon virtualities up to 5.0 GeV2 and will be compared with the available/future results of N and KY exclusive electroproduction.

·

·

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Conclusions and Outlook
·The dedicated experiment on N* studies with the CLAS12 detector at the largest photon virtualities ever achieved in exclusive meson electroproduction 5.098 % of nucleon and N* masses from QCD. see the White Paper by I.G. Aznauryan et al., ``Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction" published in Int. Journ. of Modern Physics E22 (2013) 133015 by the international group of theorists and experimentalists from USA, EU, Russia, Armenia, and Latin America.

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Back up

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


The Ground and Excited Nucleon State Structure as a Key part in Exploration of Hadron Matter
·Nucleons and pions are the first stable composite systems of quarks and gluons generated after the Big Bang by strong interaction in non-perturbative regime. They are the building blocks of atomic nuclei
The structure of the nucleon ground state from the studies of elastic form factors and different parton structure functions: Particular features of nucleon structure: ·infinite amount of contributing current quarks and gauge gluons; · leading role of quark/gluon creation and annihilation; ·all constituents are substantially off-shell; ·important role of relativistic effects; ·frame-dependence of nucleon structure. Three valence current quarks (Q) embedded in the sea of gluons (g) and qq-pairs
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Summary of the CLAS Data on Exclusive Meson Electroproduction off Protons in N* Excitation Region
Hadronic final state Covered W-range, GeV 1.1-1.40 1.1-1.55 1.1-1.7 1.1-1.40 1.1-1.7 1.1-1.7 1.5-2.0 1.65-2.35 1.65-2.35 1.7-2.1 1.8-2.5 1.7-2.6 1.3-1.6 1.4-2.1 Covered Q2range, GeV2 Measured observables d/d d/d d/d, Ab d/d d/d, Ab,At,Abt d/d d/d d/d P' d/d P' d/d Nine 1-fold differential cross sections ·d/d-CM angular distributions ·Ab,At,Abt-longitudinal beam, target, and beam-target asymmetries ·P' ­recoil polarization of strange baryon Almost full coverage of the final hadron phase space in N, +-p, p, and KY electroproduction The data are available in the CLAS Physics Data Base establiished at SINP@MSU:

C +n 0p p K+ K+
0

0.15-0.40 0.3-0.6 1.7-4.2 0.15-0.40 0.4-0.7 0.75-6.0 0.2-4.0 0.65-2.55 1.4-2.6 0.5-2.55 1.5-3.50 1.8-3.50 0.2-0.6 0.5-1.5

+-p

http://depni.sinp.msu.ru/cgi-bin/jlab/db.cgi
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Approaches for Extraction of vNN* Electrocouplings from the CLAS Exclusive Meson Electroproduction Data
· Analyses of different meson electroproduction channels independently:

+n and 0p channels:
Unitary Isobar Model (UIM) and Fixed-t Dispersion Relations (DR) I.G.Aznauryan, Phys. Rev. C67, 015209 (2003). I.G.Aznauryan et al., CLAS Coll., Phys Rev. C80, 055203 (2009).

p channel:
Extension of UIM and DR I.G.Aznauryan, Phys. Rev. C68, 065204 (2003). Data fit at W<1.6 GeV, assuming S11(1535) dominance H.Denizli et al., CLAS Coll., Phys.Rev. C76, 015204 (2007).

+-p channel:
Data driven JLAB-MSU meson-baryon model (JM) V.I.Mokeev, V.D.Burkert et al., Phys. Rev. C80, 045212 (2009). V.I.Mokeev et al., CLAS Coll., Phys. Rev. C86, 035203 (2012). Global coupled-channel analyses of the CLAS/world data of N, vN N, N, N, K, K exclusive channels: H. Kamano, S. Nakamura, T.-S. H. Lee and T. Sato, AIP Conf.Proc. 1432 (2012) 74-79. H. Kamano, S. Nakamura, T.-S. H. Lee and T. Sato, arXiv:1305.4351[nucl-th].
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Mapping Dressed Quark Mass Function
Quark mass function
I.C.Cloet, C.D.Roberts, A.W.Thomas, arXiv:1304.0855[nucl-th]

Description of N* electroexcitation in DSEQCD

pGE/GM (Q2) in DSEQCD
Similar studies for the P33(1232), P11(1440), and S11(1535) electrocouplings are in progress. ·Elastic form factors are sensitive to momentum dependence of quark mass function. ·Quark mass function extracted from elastic f.f. and vNN* electrocouploings should be the same. ·Data on vNN* electrocouplings are of particular importance in order to access dressed quark mass function and dynamical structure.
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


N* Electroexcitation in Exclusive Meson Electroproduction off Protons
Hadronic decays of prominent N*s at W<1.8 GeV.
State
(1232)P33 N(1440)P11 N(1520)D13 N(1535)S11 (1620)S
31

Bran. Fract. to N. 0.995 0.55-0.75 0.55-0.65 0.48±0.03 0.20-0.30 0.60-0.95 0.65-0.70 0.1-0.2 0.1-0.2

Bran. Fract. to N

Bran.Fract. N

CLAS data on yields of meson electroproduction at Q2<4 GeV

2

0.3-0.4 0.4-0.5 0.46±0.02 0.70-0.80 0.03-0.11 0.1-0.2 0.30-0.40 0.8-0.9 > 0.7

N(1650)S

11

N(1685)F15 (1700)D33 N(1720)P13

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


The Approaches for Extraction of vNN* Electrocouplings from N Exclusive Electroproduction off Protons
The Model based on fixed-t Dispersion Relations (DR) Unitary Isobar Model (UIM)


N N



,,


N N

N p



+

I. G.Aznauryan, Phys. Rev. C67, 015209 (2003), I.G.Aznauryan, V. D.Burkert, et al. (CLAS Collaboration), PRC 80. 055203 (2009).
K.Park talk, Session B4, Wednesday , May 29th , 16.15-16.40
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Fits to p+n Differential Cross Sections and Structure Functions
Q2=2.05 GeV
2

DR DR w/o P11 UIM

Q2=2.44

GeV

2

DR UIM

d/d



Legendre moments Dl (l=0,1,2) from various structure functions
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Quark Core vs Meson-Baryon Cloud in the Structure of P11(1440)
80 60
-1/2

40 20 0

First evaluation of the quark core contribution to the P11(1440) electrocouplings starting from QCD Lagrangian within Dyson-Schwinger Equations of QCD:
D.J.Wilson, et al, Phys. Rev. C85, 025205 (2012). ·Poincare-covariant, symmetry preserving DSEQCD evaluation. ·Account for quark mass/structure formation in dressing of bare quark by gluon cloud. ·Simplified contact interaction generates momentum independent quark mass.

A1/2*1000 GeV

-20 -40 -60 -80 0 1 2 2 Q GeV
2

A1/2

gD
3 4

2



( p - q)


G

4




m


2 G

IR

Consistent results on the quark core contribution from: DSEQCD. bare dressed global meson photo-, electro-, and m q = 0 .007 GeV m q = 0 .368 GeV hadroproduction data analysis within EBAC/ Argonne-Osaka approach. Measured dressed electrocouplings are substantially different from the estimated quark core contribution. Different data analyses suggest sizable meson-baryon cloud at Q2<5.0 GeV2 which gradually decreases with Q2 .
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013

4

IR

= 0 .93

m

= 0 .8GeV


High lying resonance electrocouplings from the +-p CLAS data analysis
A1/2*1000 GeV

MAID analysis of N electroproduction L.Tiator et al., Eur. Phys. J. Spec. Top. 198, 141 (2011). The results from +-p channel confirmed the previously available from MAID analysis of N electroproduction

1/2

0

-10 -20 -30 -40 -50

BF(N): 65-70% BF(N): 30-40%

N (1685)F15

A

1/2

A3/2*1000 GeV

Bethe-Salpeter Bonn model by M.Ronninger, B.Ch.Metsch, EPJ A49, 8 (2013). Difference between the experimental results and QM expectations is likely related to meson-baryon cloud contributions. Evaluations of meson-baryon cloud contributiions to electrocouplings of high mass resonances are needed.

1/2

Hypercentral constituent quark model by M.M.Giannini, E.Santopinto, PRC 86, 065202 (2012).

-60
140 120 100 80 60 40 20 0

0

0.2

0.4

0.6

0.8

1

Q GeV

1.2 2

1.4

2

A

3/2

0

0.2

0.4

0.6

0.8

1

Q GeV

1.2 2

1.4

2

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


High lying resonance electrocouplings from the +-p CLAS data analysis
A1/2*1000 GeV

Hypercentral constituent quark model by M.Giannini,E.Santopinto, PRC 86, 065202 (2012). Bethe-Salpeter Bonn model by M.Ronninger, B.Ch.Metsch, EPJ A49, 8 (2013). · Only known N*-state with dominant longitudinal electroexcitation at Q2>0.5 GeV2 . · This feature is well reproduced within the framework of hypercentral quark model. · Data on electrocouplings of most excited proton states in mass range up to 1.8 GeV demonstrated distinctive differences in the structure of resonances of different quantum numbers. The studies of the ground and all prominent excited state structure combined are needed in order to explore the mechanisms of the ground and N*-state formation from quarks and gluons.

-1/2

60 50 40 30 20 10 0 -10 0 0.2 0.4 0.6 0.8 1 1.2 1.4

(1620)S

31

A

1/2

Q GeV

2

2

S1/2*1000 GeV

-1/2

10 0

-10 -20 -30

S

1/2

·

-40 -50 -60 0 0.2 0.4 0.6 0.8 1 1.2 1.4

Q GeV
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013

2

2


CLAS12
Central Detector

CLAS12 supports a broad program in hadronic physics. Plans to study excited baryons and mesons: · Search for hybrid mesons and baryons · Spectroscopy of * , · N* Transition form factors at high Q2.

Forward Detector
-

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Resonance Transitions with the CLAS12
Resonance electrocouplings in regime of quark core dominance can be related to the running quark masses and their dynamical structure. 12 GeV experiment E12-09-003 will extend access to electrocouplings for all prominent N* states in the range up to Q2=12GeV2.

P11(1440) A
80 60
-1/2

1/2

accessible at 6 GeV

quark mass (GeV)

LQCD DSE
accessible at 12 GeV

Light front quark model: I.G.Aznauryan, V.D. Burkert, PRC85, 055202 (2012).

40 20 0
DSEQCD : contact interaction; realistic QCD interaction.
CLAS12 projected

A1/2*1000 GeV

-20 -40 -60 -80 0 5 2 Q GeV

2

10

Probe the transition from confinement to pQCD regimes, allowing us to explore how confinement in baryons emerge from QCD and how >98 % of baryon masses are generated non-perturbatively via dynamical chiral symmetry breaking.
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Impact of the Recent LQCD studies of N* Spectrum and Structure on the N* Program with CLAS/CLAS12
J.J.Dudek, R.G.Edwards, Phys. Rev. D85, 054016 (2012).
·each N* state with MN* <1.8 GeV has partner in computed LQCD spectrum, but level ordering is not always consistent to the data ·wave functions of the low-lying N* states dominate by 1-2 SU(6) configurations, while the wave function of high lying N*'s may contain many SU(6) configurations ·presence of hybrid-N*s with dominant contribution of hybrid components at MN*>1.9 GeV marked by

Should be verified by experiment !

New direction in N* studies proposed in V.D.Burkert, arXiv:1203.2373 [nucl-ex]: Search for hybrid N*-states looking for: overpopulation of SU(6)-multiplet; particular behavior of vNN* electrocouplings, which reflects presence of the hybrid component.
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Resonant /non-resonant contributions from the fit of +-p electroproduction cross sections within the JM model
d/dM bn/GeV

W=1.51 GeV, Q2=0.38 GeV2

W=1.51 GeV, Q2=0.43 GeV2
200 150 100 50 0 1 1.2 M 1.4 (GeV) 50 0 0.25 0.5 0.75 M+ - (GeV) 150 100 200 150 100 50 0 1 1.2 M 1.4 (GeV)

+p

-p

d/d(-cos()) (bn/rad)

30 20 10 0 0 100 200 - (deg)

20 15 10 5 0 0 100 200 + (deg)

20 15 10 5 0 0 100 200 p` (deg)

d/d() (bn/rad)

8 6 4 2 0 0 ( 200
- p)(+ p`)

8 6 4 2 0 (deg) 0 200
(+ p)(- p`)

8 6 4 2 0 (deg) 0 200
(p` p)(- +)

(deg)

Reliable isolation of the resonant cross sections is achieved

full cross sections within the JM model

resonant part

non-resonant part

V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013


Transition N-P11(1440) form factors in LQCD
Includes the quark loops in the sea , which are critical in order to reproduce the CLAS data at Q2<1.0 GeV
A1/2, S1/2 => F1*, F2
*

2

H.W. Lin and S.D. Cohen, arXiv:1108.2528

M = 390, 450, 875 MeV L box =3.0, 2.5, 2.5 f
CLAS data

·Exploratory LQCD results provide reasonable description of the CLAS data from the QCD Lagrangian. ·Prospects for LQCD evaluation with improved projection operators, approaching physical mp in the box of appropriate size.
V.I.Mokeev, 16-th Lomonosov Conference, MSU, Moscow, August 22-28, 2013