Exclusive π 0 e lectroproduction in the resonance region at high Q 2 .
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Transcript of Exclusive π 0 e lectroproduction in the resonance region at high Q 2 .
APS Meeting, April 30 2011
Exclusive π0 electroproductionin the resonance region at high Q2.
Maurizio Ungaro, Kyungseon Joo
University of ConnecticutJefferson Laboratory
for the CLAS collaboration
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Resonance Discoveryp+ + P p+ + P p- + P p- + P
p- + P p0 + N€
13A3 / 2 + 2
3A1/ 2
€
A3 / 2
€
23
(A3 / 2 − A1/ 2)
s++:s--:s-0 = 9:1:2
€
dσdΩ
= a + bcosθ + c cos2θ
€
L2I 2J = P33
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$1750
$200
Search for Quarks
Friday, May 19, 1967
Beyond CQM
gg
1,0
Constituent Counting Rule:
€
A12∝1/Q3
A32∝1/Q3
GM* ∝1/Q4
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Map the NN* electrocouplings as a function of photon virtuality with a combined analysis of electroproduction channels
Access active degrees of freedom at various distances
Explore the non-perturbative strong interactions responsible for nucleon formation and the origin of quark confinement
N* Program in CLAS
Investigate the origin of 98% of nucleon mass through DCSB
JLABCarnegie Mellon
Univ. of MarylandTrinity College (Dublin)
DSE FrameworkDCSBLCSR
Dist. Amplitudes
Form Factors
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p+ in the resonance region
Q2: 1.6 5.4 GeV2
W: 1.1 1.8 GeV58000 data points
High Q2 p electroproduction
e
e’
γv N*, △*
p+, p
n, p’p
Single p+, p production p in the Delta
Q2: 2 6.5 GeV2
W: 1.1 1.4 GeV7200 data points
Missing:p in the resonance region
Q2: 2.0 6.5 GeV2
W: 1.1 2.0 GeV~75000 data points
No prior data
h electroproduction from the same dataset1.1 W 2.0
0
Q
2
6
M. Ungaro Phys.Rev.Lett.97:112003,2006
K. Park Phys.Rev.C77:015208,2008I.G. Aznauryan Phys.Rev.C78:045209,2008
Nick Markov, UCONN
This analysis
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Experiment Overview
N
s s(W,Q2,cos(q*))
ds/dWp = sT + esL + esTTcos2f + √2e(e+)sLTcosf + h√2e(e-1)sLT’sinf
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Detect:Electron, Proton
Will Extract:
• Cross sections, Structure Functions
• Beam Spin Asymmetries• Helicity amplitudes and their
Q2 dependence
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B.H. Separation:The typical angle between the emitted photon and the electron in B.H. processes is θ m/E∼
Analysis Overview
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45 bins in W, DW=20 MeV7 bins in Q2 DQ2/Q2 ~ 0.18
10 bins in cos(q*)24, 48, 96 bins in f*
W [GeV]
Q2
[GeV
2 ]
W=1.59 Q2=3.5
Total: 75600 CS points
p0 Analysis Overview
APS Meeting, April 30 2011 Williamsburg, VA 10M.Ungaro
Preliminary Results
aTL +ess
€
sLT =b
sinθ 2ε (ε +1)
TTT
cqe
s 2sin
ds/dW* = sT + esL + esTTcos2f + √2e(e+1)sLTcosf
240 pointsout of 75K
CLAS P
relim
inary
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Preliminary Resultsds/dW* = sT + esL + esTTcos2f + √2e(e+1)sLTcosf
240 pointsout of 75K
CLAS P
relim
inaryaTL +ess
€
sLT =b
sinθ 2ε (ε +1)
TTT
cqe
s 2sin
APS Meeting, April 30 2011 Williamsburg, VA 12M.Ungaro
Preliminary Resultsds/dW* = sT + esL + esTTcos2f + √2e(e+1)sLTcosf
CLAS P
relim
inary
aTL +ess
€
sLT =b
sinθ 2ε (ε +1)
TTT
cqe
s 2sin
APS Meeting, April 30 2011 Williamsburg, VA 13M.Ungaro
Preliminary Resultsds/dW* = sT + esL + esTTcos2f + √2e(e+1)sLTcosf
CLAS P
relim
inary
aTL +ess
€
sLT =b
sinθ 2ε (ε +1)
TTT
cqe
s 2sin
APS Meeting, April 30 2011 Williamsburg, VA 14M.Ungaro
Preliminary Resultsds/dW* = sT + esL + esTTcos2f + √2e(e+1)sLTcosf
CLAS P
relim
inary
aTL +ess
€
sLT =b
sinθ 2ε (ε +1)
TTT
cqe
s 2sin
APS Meeting, April 30 2011 Williamsburg, VA 15M.Ungaro
Preliminary Resultsds/dW* = sT + esL + esTTcos2f + √2e(e+1)sLTcosf
CLAS P
relim
inary
aTL +ess
€
sLT =b
sinθ 2ε (ε +1)
TTT
cqe
s 2sin
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Summary, OutlookCL
AS Pre
limina
ry
To do list:JANR, DR (Being Done)SAID analysis
Review:p0 (by this summer)h (by this fall/winter)
The combined analysis of single and double meson channels is key to the N* program and to provide a high definition picture of the nucleon
Explore the non-perturbative strong interactions responsible for nucleon formation and the origin of quark confinement
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Backup Slides
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exclurad (Afanasev, Akushevich, Burkert, Joo)
Input: Exclusive cross section
No peaking approximation No soft-hard photon discrimination Radiation of 4 SF with angular dependence of each one (exclusive electroproduction)
Radiative Correction
W=1.29
Analysis Overview
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exclurad (Afanasev, Akushevich, Burkert, Joo)
Input: Exclusive cross section
No peaking approximation No soft-hard photon discrimination Radiation of 4 SF with angular dependence of each one (exclusive electroproduction)
Radiative Correction
W=1.63
Analysis Overview
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S1 S2
S3
S5 S6
S4
Normalization check: Good electron PID, fiducial cut Good acceptance from simulation Vertex Correction, Cuts Kinematic Corrections Elastic Scattering Inclusive scattering
Data Keppel Brasse
W [GeV]
W [GeV]
W [GeV]
W [GeV]
W [GeV]
W [GeV]
Analysis Overview
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Data:
Electron ID Proton ID Vertex Correction, Selections Electron Fiducial Cut Proton Fiducial Cut Electron Momentum Correction Proton Momentum Correction Normalization Check Radiative Correction Bin Averaging Correctionp0, h selection
Simulation:
Electron ID Proton ID Vertex Correction, Selections Electron Fiducial Cut Proton Fiducial Cut Timing Resolution Match Momentum Resolution Match Acceptance Correction
To do list:Finalize Systematic ErrorsCollaboration ReviewAmplitudes extraction (JANR, DR, SAID)
Analysis Overview
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24 f bins200M Generated Events
MAID2007AAO_RAD
Electron ID Proton ID Vertex Correction, Selections Electron Fiducial Cut Proton Fiducial Cut Timing Resolution Match Momentum Resolution Match Drift Chamber Efficiencies p0 selection
Analysis Overview
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Analysis Overview
96 f bins200M Generated Events
MAID2007AAO_RAD
Electron ID Proton ID Vertex Correction, Selections Electron Fiducial Cut Proton Fiducial Cut Timing Resolution Match Momentum Resolution Match Drift Chamber Efficiencies p0 selection
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What about h?
eP missing mass2 [GeV2]
p0
h
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What about h?
25 bins in W, DW=20 MeV7 bins in Q2 DQ2/Q2 ~ 0.18
10 bins in cos(q*)24 bins in f*
W [GeV]
Q2
[GeV
2 ]
W=1.53 Q2=3.0
Total: 43750 points
h
W [GeV]
Q2
[GeV
2 ]
W=1.65 Q2=3.0
W [GeV]
Q2
[GeV
2 ]
W=1.79 Q2=3.0
W [GeV]
Q2
[GeV
2 ]
W=1.95 Q2=3.0