Low-lying resonances of Be: Faddeev calculation with Pade’-approximates
Measurements of p(e, e’ π + )n in the ∆ (1232) and higher resonances for Q 2 ≤4.9 GeV 2
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Measurements of p(e, e’π + )n in the ∆(1232) and higher resonances for Q 2 ≤4.9GeV 2 N* 2005 Meeting Kijun Park N* 2005 Meeting Kijun Park Physics Motivation Physics Motivation Kinematics Kinematics Experiments & Analysis Process Experiments & Analysis Process Results Results Cross Section & Asymmetry Cross Section & Asymmetry Structure functions & Photocoupli Structure functions & Photocoupli ng Amplitude ng Amplitude Summary Summary
description
Measurements of p(e, e’ π + )n in the ∆ (1232) and higher resonances for Q 2 ≤4.9 GeV 2. October 12, 2005 @ Tallahassee, FL. Physics Motivation Kinematics Experiments & Analysis Process Results Cross Section & Asymmetry Structure functions & Photocoupling Amplitude Summary. - PowerPoint PPT Presentation
Transcript of Measurements of p(e, e’ π + )n in the ∆ (1232) and higher resonances for Q 2 ≤4.9 GeV 2
Measurements of p(e, e’π +)n in the ∆(1232) and higher resonances for Q2≤4.9GeV2
N* 2005 Meeting Kijun ParkN* 2005 Meeting Kijun Park
Physics MotivationPhysics Motivation KinematicsKinematics Experiments & Analysis ProcessExperiments & Analysis Process ResultsResults
Cross Section & AsymmetryCross Section & Asymmetry Structure functions & Photocoupling AmplitudeStructure functions & Photocoupling Amplitude
SummarySummary
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Close, Capstick, Simula : CQM
→ N=2 radially excited state Cano-Gonzalez : A system consisting of a hard
quark core & vector meson cloud Li-Burkert : A hybrid states with q3G P11(1440) is a pentaquark state ?
History of History of Roper Resonance Roper Resonance
Photocoupling Photocoupling AmplitudeAmplitude
Various Q2 dependences for transition form-factors are predicted by different models.
Roper signature has been clearly seen in πN and γN reactions. The unresolved low mass of P11(1440)
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Study of Resonance to understand Nucleon Structure
Most Studies for NΔ(1232) and NN*(1535) using pπ0, pρ channels
States with I=1/2 couple more to the nπ+ than pπ0
Cross Section & Asymmetry gives us information on resonances in excited states
Kinematic variable
Single pion Single pion ElectroproductionElectroproduction
Unpol. Xsection w/ one-photon exchange approx.
Asymmetry
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E1-6 Data (Oct.2001-Jan.2002)E1-6 Data (Oct.2001-Jan.2002) 5.754GeV polarized e- & LH2 ~7M nπ+ trigger after MMx cut
W[GeV] 1.1 ~ 1.8 0.02(35)
Q2[GeV2] 1.72 ~ 4.92
Variable(7)
CSCM -1.0 ~ 1.0 0.2(10)
PHICM 0. ~ 360.O 15O(24)
E1-6 Data Kinematic Coverage
Kinematic Kinematic
Bins Bins
= 58,800= 58,800
Q2[GeV2]
W[GeV] W[GeV]
MMx[GeV]Q2[GeV2]
W[GeV] W[GeV]
MMx[GeV]
Q2[GeV2]
W[GeV] W[GeV]
MMx[GeV]Q2[GeV2]
W[GeV] W[GeV]
MMx[GeV]
Particle ID (Particle ID (e-,π ++))
Electron ID : q<0, fiducial , EC, Nphe , vertex cutPion ID : q>0, fiducial, TOF mass, vertex cut
Kinematic Correction (Kinematic Correction (e-,π ++))
Applied to both Experimental, MC data
Acceptance Correction [AC]Acceptance Correction [AC]AC calculated by GSIM
Radiative Correction [RC]Radiative Correction [RC]RC done by ExcluRad (PRD 66, A. Afanasev)
Bin Centering Correction [BCC]Bin Centering Correction [BCC]BCC performed by Models(MAID03, Sato-Lee)
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Cross section as function of φ*
@ W=1.23GeV, CSCM= 0.1, Different Q2 bins
Cross section as function of W
@ CSCM= 0.1 , 0.3
φ* =67.5 o, 142.5o
Different Q2 bins
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W=1.23GeV, Q2=2.05GeV2 W=1.40GeV, Q2=2.05GeV2
MAID00
MAID03
DMTSL
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MAID00
MAID03
SL04SL
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MAID00
MAID03
SL04SL
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MAID00
MAID03
SL04SL
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//
MAID00
MAID03
DMTMAID98
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Quark Models
This Work
GWU (VPI) pion photoproduction
RPP estimation
ηelectro-, photo- production IM, DR
π electro- production IM, DR
π -2π analysis
Relativistic Quark ModelNon-relativistic Quark ModelBonn, DESY, NINA, Jlab(η)
Light-front calculation
q3G hybrid state
re-analyze the old data MAINZ
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Differential Cross Section has been measured first time completely over all angular range in 1.1 < W < 1.8GeV at high 1.7 < Q2 < 4.9GeV2
Electron Beam Asymmetry has been measured in same kinematic region.
Measurement of Cross Section and Asymmetry have been compared to recent physics models such as MAID’s, Sato-Lee, DMT etc.
σT+εLσL , σTT , σLT , σLT / Structure Functions have been extracte
d.
The Cross Section and Beam Spin Asymmetry are fitted to extract the Transition Form Factors and compared with present predictions.
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BACKUP SLIDES
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I. The hadrons constitute most of the visible matter.II. The contribution of the current quark masses into total
baryon mass is very small; most of the hadron mass comes from strong interactions.
III. Investigation of the spectrum and the internal structure of the hadrons provides information about the underlying strong interactions.
IV. One of the physics goals of the JLab is to investigate the strong interactions in the confinement regime.
Why we are interested in Why we are interested in Hadron Physics ??Hadron Physics ??
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Elastic Scattering Target stays intact and holds. A good tool to study the ground state of the nucleon
Deep Inelastic Scattering Energy transfer is large, target is broken apart. A good tool to study the quark-gluon content of the nucleon at
small distances. Resonance excitation
The target is excited into a single bound system. Allows us to study the internal structure of the ground and the
excited states, and very useful for the exclusive reactions. Key : Nπ decay channels of the intermediate excited states. This analysis covers not only Δ(1232) but high res
onance states.
Electron Electron ScatteringScattering
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Quarks are fundamental particle of hadrons. Quarks interact with each other through eight
gluon fields in QCD : SU(3) gauge theory QCD has a complicate picture for solution at
long distances.
Nucleon consists 3 constituent quarks (~300MeV) in a confined potential in constituent quark model.
Presence of Color tensor forces ; spin-spin interaction (Break the spherical symmetry of the ground state)
Simplified other degrees of freedom (pions) may be needed.
Quark Quark ModelModel
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The electroproduction of an excited state can be described in terms of 3 photocoupling amplitudes A1/2, A3/2 and S1/2 .
Describable pion electroproduction using multipole amplitude El, Ml and Sl .
l : the orbital angular momentum in Nπ system.
The ± sign indicates how the spin of proton couples to the orbital momentum.
For each resonance there is one-to-one connection between multipole and helicity amplitudes.
p
*
N
N*
El, Ml ,Sl
A1/2, A3/2,S1/2
Electroproduction Electroproduction AmplitudesAmplitudes
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One of the first observed baryon resonances.
Spin J=3/2 and isospin I=3/2. From angular momentum and parity co
nservation γN Δ transition can be induced by E2, M1 and C2 multipoles.
SU(6)xO(3) symmetric quark model describes γN Δ transition as a single quark spin flip.
If SU(6)xO(3) spatial wave functions are pure L=0, then γN Δ transition can only be induced by j=1 photons, i.e. only M1+ allowed.
D-waves in the wave function will allow for E1+ and S1+ contributions.
e
e /*
e
e /*
More sophisticated models allow for explicit pion degrees of freedom (pion cloud).
pion cloud can also introduce E1+ and S1+ contributions.
M1
P(938) J=1/2
(1232) J=3/2
∆∆(1232)Resonan(1232)Resonancece
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e-
Particle ID (Particle ID (e-,π ++))
Θπ =20o
φπ
θπ
φπ
Fiducial Volume cutFiducial Volume cut
((e-,π ++))
Kinematic Kinematic CutsCuts
π+
p
ph
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Mass of Proton from elastic Mass of Neutron from nπ +
Kinematic Kinematic CorrectionCorrectionss
After Kine. Corr. For GSIM Vertex Corr. & Cut
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Angle dependent RC W dependent RC
AC & RC AC & RC CorrectionsCorrections
σ = 0.0372 σ = 0.0368
tvertextvertex
Acceptance vs. PHICM
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Ratio between elastic cross section and Bosted FFP(Rad) vs. electron angle
Elastic Cross Section
Inelastic Cross Section
Q2 dependence of inelastic cross section @ W=1.21GeV
W dependence of inelastic cross section @ Q2=2.5GeV2
Bin correction by sub-binning from two models @ W=1.23GeV, CSCM=0.1, two Q2 bins
NormalizatioNormalizationn
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Electron Beam Asymmetry
Asymmetry in W=1.39GeV @ Q2=1.72, 2.05GeV2& Compare to calculation from five different Physics Models
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Electron Beam Asymmetry
Asymmetry in W=1.39GeV @ Q2=2.44, 2.91GeV2& Compare to calculation from five different Physics Models
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Systematic Uncertainties Criteria Avg.
Electron identification (S.F.) 3.0σ→3.5σ
Resol. 4.1%
Electron fiducial cut ( -10% width)
Width 2.3%
Pion identification 3.0σ→3.5σ
Resol. 1.4%
Pion fiducial cut ( -10% width)
Width 3.3%
Missing mass cut 3.0σ→2.0σ
Resol. 1.0%
Vertex cut ( -5% cut)
Width 1.0%
LH2 target Density/Length
< 1.0%
Radiative Corr. MAID00/03 Evnt ratio < 0.4%
Acceptance Corr. MAID00/03 Evnt ratio < 1.0%
Total 6.3%
Systematic Systematic UncertaintiesUncertainties
Tot. sys.
pi fidu .sys.
e PID. sys.e fidu. sys.
MMx. sys.Z-vtx. sys.
pi PID. sys.
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5-th Structure Function
σLTP @ W =1.39GeV in five different Q2 bins
& Compare to calculation from Physics Models
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/ / * / *0 1 1 2 2
/ * *0 1 1 1 0 0 1 1
/ * *1 1 1 1 1 1 1
/ * *2 2 2 1 1 2
(cos ) (cos )
Im[( 3 ) ( 2 ) ]
6 Im[( ) ]
12 Im[( ) 2 ]
LTP D D P D P
D M M E S E S S
D M M E S E S
D M E S E S
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Legendre moment as function of W[GeV]
D0/(W),D1
/ (W) : fit from Pl=2,3,4(cosθ)
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Model comparison MAID2000 & 2003
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Dependence of S1/2 , A1/2
MAID2003
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Dependence of S1/2 , A1/2 MAID2003 Q2=2.GeV2
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Dependence of S1/2 , A1/2 MAID2003 Q2=2.GeV2
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Dependence of S1/2 , A1/2 MAID2003 Q2=2.GeV2
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σLTP vs. W @ Q2=1.72GeV2, CSCM<0.
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σLTP vs. W @ Q2=1.72GeV2, CSCM>0.
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σLTP vs. W @ Q2=2.05GeV2, CSCM<0.
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σLTP vs. W @ Q2=2.05GeV2, CSCM>0.
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σLTP vs. W @ Q2=2.44GeV2, CSCM<0.
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σLTP vs. W @ Q2=2.44GeV2, CSCM>0.
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σLTP vs. W @ Q2=2.91GeV2, CSCM<0.
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σLTP vs. W @ Q2=2.91GeV2, CSCM>0.
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Legendre moment as function of W[GeV]D0
/(W),D1/ (W) :MAID2003
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Legendre moment vs. Q2 at P11(1440)
D0/(Q2) D1
/ (Q2) D0/(Q2) D1
/ (Q2)Various Models MAID2003
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D0/(W), D1
/ (W), D0/(Q2), D1
/(Q2)
Legendre moment as function of W, Legendre moment as function of W, QQ22
σLTP = D0/+D1
/P1(cosθ)+D2/P2(cosθ)
W dependence Q2 dependence
A1/2 sensitive to imaginary part of M1- ,S1-
