October 12, 2005 @ Tallahassee, FL Measurements of p(e, e’π +)n in the ∆(1232) and higher resonances for Q2≤4.9GeV2 October 12, 2005 @ Tallahassee, FL Physics Motivation Kinematics Experiments & Analysis Process Results Cross Section & Asymmetry Structure functions & Photocoupling Amplitude Summary N* 2005 Meeting Kijun Park

History of Roper Resonance Physics Motivation ? History of Roper Resonance Roper signature has been clearly seen in πN and γN reactions. The unresolved low mass of P11(1440) 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 ? ? Various Q2 dependences for transition form-factors are predicted by different models. Photocoupling Amplitude 10/12/05 N*2005-K.Park

Single pion Electroproduction Kinematics Single pion Electroproduction Kinematic variable Unpol. Xsection w/ one-photon exchange approx. s-channel t-channel Physics motivation 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 Asymmetry 10/12/05 N*2005-K.Park

Experimental Data E1-6 Data (Oct.2001-Jan.2002) Kinematic Bins E1-6 Data Kinematic Coverage 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) Kinematic Bins = 58,800 Particle ID (e-,π+) Electron ID : q<0, fiducial , EC, Nphe , vertex cut Pion ID : q>0, fiducial, TOF mass, vertex cut Kinematic Correction (e-,π+) Applied to both Experimental, MC data Acceptance Correction [AC] AC calculated by GSIM Radiative Correction [RC] RC done by ExcluRad (PRD 66, A. Afanasev) Bin Centering Correction [BCC] BCC performed by Models(MAID03, Sato-Lee) High quality electron beam polarization, stable target status during e1-6 The same Kinematic correction technique applied to both MC, real data 10/12/05 N*2005-K.Park

Cross section vs. PHICM , W 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 10/12/05 N*2005-K.Park

Asymmetry vs. PHICM W=1.23GeV, Q2=2.05GeV2 W=1.40GeV, Q2=2.05GeV2 MAID00 MAID03 DMT SL W=1.23GeV, Q2=2.05GeV2 W=1.40GeV, Q2=2.05GeV2 10/12/05 N*2005-K.Park

Structure Function : MAID00 MAID03 SL04 SL 10/12/05 N*2005-K.Park

Structure Function : MAID00 MAID03 SL04 SL 10/12/05 N*2005-K.Park

Structure Function : MAID00 MAID03 SL04 SL 10/12/05 N*2005-K.Park

/ Structure Function : MAID00 MAID03 DMT MAID98 10/12/05 N*2005-K.Park

A 1/2 S 1/2 Photo-coupling Amp. ; preliminary Quark Models Light-front calculation preliminary q3G hybrid state π-2π analysis π electro- production IM, DR ηelectro-, photo- production IM, DR RPP estimation GWU (VPI) pion photoproduction This Work Relativistic Quark Model Non-relativistic Quark Model Bonn, DESY, NINA, Jlab(η) re-analyze the old data MAINZ 10/12/05 N*2005-K.Park

Photo-coupling Amp. ; A 1/2 A 3/2 S 1/2 preliminary 10/12/05 N*2005-K.Park

Summary 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 extracted. The Cross Section and Beam Spin Asymmetry are fitted to extract the Transition Form Factors and compared with present predictions. 10/12/05 N*2005-K.Park

BACKUP SLIDES 10/12/05 N*2005-K.Park

Why we are interested in Hadron Physics ?? The hadrons constitute most of the visible matter. The contribution of the current quark masses into total baryon mass is very small; most of the hadron mass comes from strong interactions. Investigation of the spectrum and the internal structure of the hadrons provides information about the underlying strong interactions. One of the physics goals of the JLab is to investigate the strong interactions in the confinement regime. 10/12/05 N*2005-K.Park

Electron Scattering Elastic Scattering Deep Inelastic 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 resonance states. 10/12/05 N*2005-K.Park

Quark Model 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. In the constituent quark model the nucleon consists of 3 “fat” ~300 MeV constituent quarks in a confining potential. Presence of Color tensor forces, such as spin-spin interaction, which can break the spherical symmetry of the ground state. May be too simplified, other degrees of freedom, such as pions, may be needed. 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. 10/12/05 N*2005-K.Park

Electroproduction Amplitudes 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 g* N N* El, Ml ,Sl A1/2, A3/2,S1/2 10/12/05 N*2005-K.Park

One of the first observed baryon resonances. Spin J=3/2 and isospin I=3/2. From angular momentum and parity conservation 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. ∆(1232)Resonance g M1 P(938) J=1/2 D(1232) J=3/2 e / e More sophisticated models allow for explicit pion degrees of freedom (pion cloud). pion cloud can also introduce E1+ and S1+ contributions. e / e 10/12/05 N*2005-K.Park

Kinematic Cuts e- π+ p φπ Particle ID (e-,π+) ph Fiducial Volume cut Particle identification as an electron Θπ=20o φπ θπ 10/12/05 N*2005-K.Park

Kinematic Corrections Mass of Proton from elastic Mass of Neutron from nπ+ Kinematic Corrections Vertex Corr. & Cut 10/12/05 N*2005-K.Park After Kine. Corr. For GSIM

AC & RC Corrections DATA GSIM σ = 0.0372 σ = 0.0368 tvertex W dependent RC Angle dependent RC Acceptance vs. PHICM 10/12/05 N*2005-K.Park

Normalization Elastic Cross Section Ratio between elastic cross section and Bosted FFP(Rad) vs. electron angle Inelastic Cross Section W dependence of inelastic cross section @ Q2=2.5GeV2 Normalization Bin correction by sub-binning from two models @ W=1.23GeV, CSCM=0.1, two Q2 bins Q2 dependence of inelastic cross section @ W=1.21GeV 10/12/05 N*2005-K.Park

Electron Beam Asymmetry Asymmetry in W=1.39GeV @ Q2=1.72, 2.05GeV2 & Compare to calculation from five different Physics Models 10/12/05 N*2005-K.Park

Electron Beam Asymmetry Asymmetry in W=1.39GeV @ Q2=2.44, 2.91GeV2 & Compare to calculation from five different Physics Models 10/12/05 N*2005-K.Park

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 1.4% Pion fiducial cut ( -10% width) 3.3% Missing mass cut 3.0σ→2.0σ 1.0% Vertex cut ( -5% cut) LH2 target Density/Length < 1.0% Radiative Corr. MAID00/03 Evnt ratio < 0.4% Acceptance Corr. MAID00/03 Total 6.3% Tot. sys. e PID. sys. e fidu. sys. pi PID. sys. pi fidu .sys. Z-vtx. sys. MMx. sys. 10/12/05 N*2005-K.Park

5-th Structure Function σLTP @ W =1.39GeV in five different Q2 bins & Compare to calculation from Physics Models 10/12/05 N*2005-K.Park

10/12/05 N*2005-K.Park

D0/(W),D1/ (W) : fit from Pl=2,3,4(cosθ) Legendre moment as function of W[GeV] D0/(W),D1/ (W) : fit from Pl=2,3,4(cosθ) 10/12/05 N*2005-K.Park

Model comparison MAID2000 & 2003 10/12/05 N*2005-K.Park

Dependence of S1/2 , A1/2 MAID2003 Main sensitivity came from M1-, S1- 10/12/05 N*2005-K.Park

Dependence of S1/2 , A1/2 MAID2003 Q2=2.GeV2 10/12/05 N*2005-K.Park

Dependence of S1/2 , A1/2 MAID2003 Q2=2.GeV2 10/12/05 N*2005-K.Park

Dependence of S1/2 , A1/2 MAID2003 Q2=2.GeV2 10/12/05 N*2005-K.Park

σLTP vs. W @ Q2=1.72GeV2, CSCM<0. 10/12/05 N*2005-K.Park

σLTP vs. W @ Q2=1.72GeV2, CSCM>0. 10/12/05 N*2005-K.Park

σLTP vs. W @ Q2=2.05GeV2, CSCM<0. 10/12/05 N*2005-K.Park

σLTP vs. W @ Q2=2.05GeV2, CSCM>0. 10/12/05 N*2005-K.Park

σLTP vs. W @ Q2=2.44GeV2, CSCM<0. 10/12/05 N*2005-K.Park

σLTP vs. W @ Q2=2.44GeV2, CSCM>0. 10/12/05 N*2005-K.Park

σLTP vs. W @ Q2=2.91GeV2, CSCM<0. 10/12/05 N*2005-K.Park

σLTP vs. W @ Q2=2.91GeV2, CSCM>0. 10/12/05 N*2005-K.Park

D0/(W),D1/ (W) :MAID2003 Legendre moment as function of W[GeV] 10/12/05 N*2005-K.Park

Legendre moment vs. Q2 at P11(1440) Various Models MAID2003 D0/(Q2) D1/ (Q2) D0/(Q2) D1/ (Q2) 10/12/05 N*2005-K.Park

Legendre moment as function of W, Q2 σLTP = D0/+D1/P1(cosθ)+D2/P2(cosθ) D0/(W), D1/ (W), D0/(Q2), D1/(Q2) D0, D1 have dominant dependence of M1-, S1- A1/2 sensitive to imaginary part of M1- ,S1- W dependence Q2 dependence 10/12/05 N*2005-K.Park