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Single Single 00 Electroproduction in the Electroproduction in the Resonance Region with CLASResonance Region with CLAS

Kyungseon Joo

University of Connecticut

For the CLAS Collaboration

N* 2009

Beijing, China

April 19, 2009

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SU(6)xO(3) Classification of Low Lying N*

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p(e,e’)X

Exclusive Processes in N* StudiesCLAS

Hadronic mass

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N* Transition Form Factors in the 2nd N* Transition Form Factors in the 2nd Resonance Region –Resonance Region –

“Roper” P11(1440), S11(1535), D13(1520)

Transition Form Factors of Low Lying N* States

p0 channel is important to study:

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Roper P11(1440) Helicity amplitudes

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+

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Transverse amplitudes for p->D13(1520)

preliminar

y

preliminar

y

+

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CLAS Single Pion Electro-production DataCLAS Single Pion Electro-production Data

Data in the region up to W = 1.4 GeV

JLab/Hall C Frolov 1999 p0 Q² = 2.5 - 4.3 GeV²

Bates Mertz et al. 2001 p0 Q² = 0.127 GeV²

Mainz Pospischil et al. 2001 p0 Q² = 0.127 GeV²

JLab/CLAS Joo et al. 2002 p0 Q² = 0.4 – 1.8 GeV²

Bonn Bantes, Gothe 2002 p0 Q² = 0.6 GeV²

JLab/CLAS Egiyan et al. 2006 n+ Q² = 0.3 – 0.6 GeV²

Mainz Elsner et al. / Stave et al.

2006 p0 Q² = 0.05-0.2 GeV²

Jlab/CLAS Ungaro et al. 2006 p0 Q² = 3.0 – 6.0 GeV²

JLab/Hall A Kelly et al. 2007 p0 Q² = 1.0 GeV²

JLab/CLAS Park et al. 2008 n+ Q² = 3.0 – 6.0 GeV²

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CLAS Single Pion Electro-production DataCLAS Single Pion Electro-production Data

Data up to the 3rd resonance region up to W = 1.7 GeV

JLab/CLAS Joo et al. (Ae only)

2003 p0 Q² = 0.4 – 0.65 GeV²

JLab/CLAS Joo et al. (Ae only)

2004 n+ Q² = 0.4 - 0.65 GeV²

JLab/Hall A Laveissiere et al. 2004 p0 Q² = 1.0 GeV²

JLab/CLAS Egiyan et al. 2006 n+ Q² = 0.3 – 0.6 GeV²

JLab/CLAS Park et al. 2008 n+ Q² = 1.7 – 4.5 GeV²

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CLAS Single CLAS Single 00 Electro-production Data Analysis Electro-production Data Analysis

• E1E: • Beam Energy:1 GeV and 2 GeV • Low Q2 up to 1.5 GeV, and W up to 1.7 GeV

•E1-6: • Beam Energy: 5.75 GeV • Low Q2, up to 4.5 GeV and W up to 2.0 GeV

• Beam polarization: ~ 70 – 80 %

• Target: Liquid Hydrogen

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CEBAF at Jefferson Lab

Emax ~ 6 GeV

Imax ~ 200 A

Duty Factor ~ 100% E/E ~ 2.5

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Beam P ~ 80%E(tagged) ~ 0.8- 5.5 GeV

CLASA CB

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CEBAF Large Acceptance Spectrometer (CLAS)

/q e e

p

/e •Six identical sectors

•5 T toroidal B-field

•Δθ=15-140 degrees

•Δφ = 0-50 degrees

•Δp/p = 10-2-10-3

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Electron PIDElectron PID

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Electron PIDElectron PID

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Proton PIDProton PID

Use TOF timing and DC momentum of positive tracks

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00 selection selection e + p -> e’ + p + X on resonance region from 5.7 GeV

MX2

MX2 from e + p -> e’ + p + X

on resonance region from 2. 0 GeV

MX2

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00 selection (E1-6) selection (E1-6)

MX2 from e + p -> e’ + p + X

for 1.1 < W < 2.0 GeVM

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MX2

Currently working on bench-mark studies on (1232) region with/without tagging 0

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Typical ep→ e’pπ0 cross sections vs cos θ* and φ*

Q2 = 0.2 GeV2 W=1.22 GeV

Very preliminary

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π+ electroproduction at Q2=0.20 GeV2 using CLAS

Very preliminary

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0.6 < Q2 < 0.7, 1.3 < W < 1.35

Differential Cross section from 2.0 GeV Differential Cross section from 2.0 GeV

Very preliminary

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2

0

)(cosi

iiiLT PA

0.6 < Q2 < 0.7

Legendre MomentLegendre Moment

Very preliminaryA0

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E1+/M1+ and S1+/M1+

pπ0 only

nπ+ only

pπ0 and nπ+

CLAS e1e UIM Fit

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Roper P11(1440) Helicity amplitudes

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Transverse amplitudes for p->D13(1520)

preliminar

y

preliminar

y

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Summary

• Single electro-production analysis is under way for low and high Q2 range up to 2.0 GeV in W.

• Able to perform combined analysis with n+ and two pion channels

•p channel is an important part of 12 GeV N* program with CLAS12.

• Current p analysis measuring all final states will provide an important step for 12 GeV N* program.