Workshop scope and N* parameters available/expected
Victor I. Mokeev
from the CLAS/CLAS12 detector data.
Jefferson Lab
Victor I. Mokeev
Jefferson Lab
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
Nucleon Resonance Studies with CLAS12
R. Arndt4, H. Avakian6, I. Aznauryan11, A. Biselli3, W.J. Briscoe4, V. Burkert6,
V.V. Chesnokov7, P.L. Cole5, D.S. Dale5, C. Djalali10, L. Elouadrhiri6, G.V. Fedotov7,
T.A. Forest5, E.N. Golovach7, R.W. Gothe*10, Y. Ilieva10, B.S. Ishkhanov7,
E.L. Isupov7, K. Joo9, T.-S.H. Lee1,2, V. Mokeev*6, M. Paris4, K. Park10,
N.V. Shvedunov7, G. Stancari5, M. Stancari5, S. Stepanyan6, P. Stoler8,
I. Strakovsky4, S. Strauch10, D. Tedeschi10, M. Ungaro9, R. Workman4,
and the CLAS Collaboration
Approved by PAC for 40 days beam time
for the first five years of running
http://www.jlab.org/exp_prog/proposals/09/PR12-09-003.pdf.
Argonne National Laboratory (IL,USA)1, Excited Baryon Analysis Center (VA,USA)2,
Fairfield University (CT, USA)3, George Washington University (DC, USA)4,
Idaho State University (ID, USA)5, Jefferson Lab (VA, USA)6,
Moscow State University (Russia)7, Rensselaer Polytechnic Institute (NY, USA)8,
University of Connecticut (CT, USA)9, University of South Carolina (SC, USA)10,
and Yerevan Physics Institute (Armenia) 11
Spokesperson
Contact Person*
V.I.Mokeev
Meeting, June
V.I.Mokeev
NSTAR atUser
high Group
Q2 Workshop
May 18
16,2008
2011, Jefferson Lab, Newport News, VA
2
Anticipated N* Electrocouplings from a Combined Analysis of Np & Npp
P11(1440)
D13(1520)
S11(1535)
CLAS
Hall C
CLAS
CLAS
Open circles represent projections and all other markers the available results with the 6-GeV
electron beam
Examples of published and projected results obtained within 60d for three prominent
excited proton states from analyses of Np and Npp electroproduction channels. Similar
results are expected for many other resonances at higher masses, e.g. S11(1650),
F15(1685), D33(1700), P13(1720), …
Our experiment will – for the foreseeable future – be the only experiment that can
provide data on gvNN* electrocouplings for almost all well established excited proton
states at the highest photon virtualities ever achieved in N* studies up to Q2 of 12 GeV2
3
V.I.Mokeev
Meeting, June
V.I.Mokeev
NSTAR atUser
high Group
Q2 Workshop
May 18
16,2008
2011, Jefferson Lab, Newport News, VA
gvNN* Electrocouplings at Q2>5.0 GeV2 as a probe of the Resonance Quark
Structure
Meson-Baryon
D13(1520)
P11(1440)
Dressing
absolute values of
meson-baryon dressing
amplitudes ( EBAC)
quark core contributions
(constituent quark
models)
CLAS: Np
and Np/Npp
combined (Phys. Rev. C80, 055203, 2009)
Resonance structures can be described in terms of an internal quark core and a
surrounding meson-baryon cloud whose relative contribution decreases with
increasing Q2.
Data on gvNN* electrocouplings from this experiment (Q2 > 5 GeV2) will afford for the
first time direct access to the non-perturbative strong interaction among dressed
quarks, their emergence from QCD, and the subsequent N* formation.
4
V.I.Mokeev
Meeting, June
V.I.Mokeev
NSTAR atUser
high Group
Q2 Workshop
May 18
16,2008
2011, Jefferson Lab, Newport News, VA
gvNN* Electrocouplings at Q2>5.0 GeV2 as a probe
of the Resonance Quark Structure
Topic for discussion:
Prospects to establish the area of Q2 with minor meson-baryon
dressing for N* states of various quantum numbers within the
framework of the EBAC-DCC approach
V.I.Mokeev
Meeting, June
V.I.Mokeev
NSTAR atUser
high Group
Q2 Workshop
May 18
16,2008
2011, Jefferson Lab, Newport News, VA
Theory Support Group
I.Aznauryan9, V.M. Braun8, S.Capstick3, I.Cloët10, R. Edwards6, M.M. Giannini5,7,
B. Julia-Diaz2, H. Kamano2, T.-S.H. Lee1,2, A. Lenz8, H.W. Lin6, A. Matsuyama2,
C.D. Roberts1, E. Santopinto5,7, T. Sato2, G. Schierholz8, N. Suzuki2, Q. Zhao4,
and B.-S. Zou4
Argonne National Laboratory (IL,USA)1, Excited Baryon Analysis Center (VA,USA)2,
Florida State University(FL,USA)3 Institute of High Energy Physics (China)4,
Istituto Nazionale di Fisica Nucleare (Italy)5, Jefferson Lab (VA, USA)6, University
of Genova (Italy)7,University of Regensburg (Germany)8, Yerevan Physics
Institute (Armenia)9 and University of Washington (WA, USA)10
:
“Theory Suport for the Excited Baryon Program
at the JLAB 12 GeV Upgrade” ,
arXiv:0907.1901[nucl-th].
V.I.Mokeev
Meeting, June
V.I.Mokeev
NSTAR atUser
high Group
Q2 Workshop
May 18
16,2008
2011, Jefferson Lab, Newport News, VA
6
Major directions in theoretical interpretation of gvNN*
electrocouplings
•Interpretation of gvNN* electrocouplings in LQCD.
• QCD-based description of gvNN* electrocouplings
within the framework of DSE.
•Combined LQCD and Light Cone Sum Rule
(LCSR) approach.
•Constituent Quark Models.
V.I.Mokeev
Meeting, June
V.I.Mokeev
NSTAR atUser
high Group
Q2 Workshop
May 18
16,2008
2011, Jefferson Lab, Newport News, VA
N* electrocouplings from LQCD
Current calculations with mp~0.5 GeV ,
stable P11(1440) and limited operator basis
F1,2 form factors for P-P11(1440)
transition (exploratory calculations)
Topics for discussion:
• Which N* parameters can be
evaluated in LQCD for unstable
excited states?
• Prospects to determine gvNN*
electrocouplings from the QCD
Lagrangian at Q2 >5.0 GeV2,
approaching physical pion
mass and appropriate box size.
H.W.Lin et al, Phys.Rev. D78, 114508 (2008)
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
LQCD & Light Cone Sum Rule (LCSR) Approach
V.Braun et al., Phys. Rev. Lett.,103,072001 (2009).
S11(1535)
CLAS
Hall C
mp=380 MeV
mp=280 MeV
Topics for discussions:
•The prospects for evaluation of S11(1535) electrocouplings at
Q2>2.0 GeV2 with pion masses closer to physical limit.
•Can these evaluations be extended for others parity partners?
•Prospect to relate results on gvNN* electrocouplings and quark
distribution amplitudes in N*’s.
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
Dyson-Schwinger Equation (DSE) Approach
strong confinement
L.Chang et al, PRL 106, 072001 (2011)
quark anom.
electro magn.
moment
quark anom. chromomagn. moment
Topics for discussions:
•The prospects to observe manifestation of running dynamical quark
masses and structure in Q2 evolution of N* electrocouplings
• Prospects to compare LQCD and DSE evaluation for quark/gluon
propagators and quark-gluon vertices in infrared
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
Constituent Quark Models
• Only available tool to evaluate electrocouplings of most N* states
• Electrocouplings of most excited proton states are already available
at Q2<4.0 GeV2 from hQCM by M. Giannini/E. Santopinto
Topics for discussions:
• Light front and other approaches for relativistic treatment
• High Fock components at high Q2
• Prospects of AdS/CFT in describing N* electrocouplings at high Q2
How constituent quark models can be related to QCD in
the domain 2.0<Q2<10 GeV2, where quark mass running
becomes most evident ??
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
N* parameters from analyses of exclusive electroproduction channels
Resonant amplitudes
p, h, pp,..
γv
*
N*,△
N’
N
A3/2, A1/2, S1/2
GM, GE, GC
Non-resonant amplitudes
p, h, pp,..
+
N
N’
A1/2, A3/2, and S1/2 electrocouplings are proportional to the helicity
amplitudes for transition between the initial photon-proton state of the
initial particle helicities, and the final state with unstable N*, D*
resonances. Electrocouplings are well defined, directly related to N*
structure and are part of observable quantities, e.g. cross sections.
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
N* parameters from analyses of exclusive electroproduction
channels
• Separation of resonant/non-resonant contributions represents most
challenging part, and can be achieved within the framework of reaction
models.
• N* ‘s can couple to various exclusive channels with entirely different
non-resonant amplitudes, while their electrocouplings should remain the
same.
• Consistent results from the analyses of major meson electroproduction
channels show that model uncertainties in extracted N* electrocouplings
are under control.
• Will similar strategy be feasible for LQCD evaluation of gvNN*
electrocouplings?
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
gvNN* electrocouplings from the CLAS data on Np/Npp
electroproduction
Npp CLAS
preliminary.
A1/2
Np CLAS
I. Aznauryan,V. Burkert,
et al., PRC 80,055203
(2009).
P11(1440)
S1/2
P11(1440)
Np world
V. Burkert, et al., PRC
67,035204 (2003).
Np
Q2=0,
A3/2
A3/2
D13(1520)
PDG.
Np Q2=0, CLAS
M. Dugger, et al., PRC
79,065206 (2009).
F15(1685)
Good agreement between the electrocouplings obtained from the Np and Npp
channels. N* electrocouplings are measurable and model independent quantities.
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
The web-page with the data on gvNN*
electrocouplings
Numerical results on gvNN* electrocouplings determined from analyses
of meson electroproduction data may be found in:
http://www.jlab.org/~mokeev/resonance_electrocouplings/
Relations between gvNN* electrocouplings and N* electromagnetic
decay widths are given under the link “Definition”
The web-page incorporates all CLAS results, and only available
for us part of the gvNN* electrocouplings obtained worldwide
The CLAS data on ND electromagnetic form factors are
published in I.G. Aznauryan, et al., PRC 80, 055203 (2009)
All comments can be sent to V.Mokeev mokeev@jlab.org. Submission
of the results on gvNN* electrocouplings is encouraged!
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
Reaction models for extraction of gvNN*
electrocouplings at Q2>5.0 GeV2
• Separation between resonant/non-resonant
contributions in N* analyses carried out so far was
achieved employing reaction models with mesonbaryon (MB) degrees of freedom.
• At Q2>5.0 GeV2 MB degrees of freedom are mostly
replaced by relevant quark degrees of freedom. Such
a behavior is encoded in MB vertices cut-off
parameters (L2~1.0 GeV2), and supported by
preliminary analyses of the CLAS p+p-p data at Q2>2.0
GeV2.
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
Reaction models for extraction of gvNN*
electrocouplings at Q2>5.0 GeV2
• Reaction models are needed for description of Np and
Npp electroproduction at W<2.0 GeV and Q2>5.0 GeV2
that employ relevant quark degrees of freedom, and
which are capable of describing non-resonant
contributions to p+n, p0p, pD and rp reaction channels,
at least.
• Combined approaches that incorporate superposition
of explicit MB/quark mechanisms and
phenomenological parametrization of remaining
contributions represent a reasonable initial option.
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
Preliminary analysis of the CLAS π+π-p electroproduction
data at Q2>2.0 GeV2
Data fit requires to increase effective coupling with p-Regge trajectory by a
factor ~1.8
Indication of the transition to other degrees of freedom
Q2 (GeV2)
0.65
0.95
1.30
2.30
2.70
3.30
D33, P13 ,F15
3/2+(1720)
3.90
4.60
Extension of JM model toward high Q2
D13
Resonance structures become more
prominent with increasing Q2.
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA
Workshop Expectations
 Tools for based on QCD theoretical interpretations of
gvNN* electrocouplings
 further development
 Reaction models for Np and Npp electroproduction at
W<2.0 GeV and Q2>5.0 GeV2
 establishment of the framework, commitments…..
 The White Paper
V.I.Mokeev NSTAR at high Q2 Workshop , May 16, 2011, Jefferson Lab, Newport News, VA