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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 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.

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Measurements of p(e, e’ π + )n in the ∆ (1232) and higher resonances for Q 2 ≤4.9 GeV 2

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  1. Measurements of p(e, e’π+)nin 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

  2. 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 N*2005-K.Park

  3. Kinematics Single pion Electroproduction Kinematic variable • 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 Unpol. Xsection w/ one-photon exchange approx. s-channel t-channel Asymmetry N*2005-K.Park

  4. 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) Experimental Data • E1-6 Data Kinematic Coverage • E1-6 Data (Oct.2001-Jan.2002) • 5.754GeV polarized e- & LH2 • ~7M nπ+ trigger after MMx cut • Kinematic Bins = 58,800 N*2005-K.Park

  5. 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 N*2005-K.Park

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

  7. MAID00 MAID03 SL04 SL Structure Function : N*2005-K.Park

  8. MAID00 MAID03 SL04 SL Structure Function : N*2005-K.Park

  9. MAID00 MAID03 SL04 SL Structure Function : N*2005-K.Park

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

  11. S A 1/2 1/2 Photo-coupling Amp. ; Light-front calculation Quark Models preliminary q3G hybrid state π-2πanalysis πelectro- 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 N*2005-K.Park

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

  13. 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. N*2005-K.Park

  14. BACKUP SLIDES N*2005-K.Park

  15. 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. N*2005-K.Park

  16. Electron Scattering • 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 resonance states. N*2005-K.Park

  17. 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. • 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. N*2005-K.Park

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

  19. gM1 P(938) J=1/2 D(1232) J=3/2 ∆(1232)Resonance • 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+ andS1+ contributions. e / e • More sophisticated models allow for explicit pion degrees of freedom (pion cloud). • pion cloud can also introduce E1+ andS1+ contributions. e / e N*2005-K.Park

  20. π+ p ph φπ e- Θπ=20o φπ θπ Kinematic Cuts • Particle ID (e-,π+) • Fiducial Volume cut (e-,π+) N*2005-K.Park

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

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

  23. 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 N*2005-K.Park

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

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

  26. pi fidu .sys. Tot. sys. e fidu. sys. MMx. sys. pi PID. sys. e PID. sys. Z-vtx. sys. Systematic Uncertainties N*2005-K.Park

  27. 5-th Structure Function σLTP @ W =1.39GeV in five different Q2 bins & Compare to calculation from Physics Models N*2005-K.Park

  28. N*2005-K.Park

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

  30. Model comparison MAID2000 & 2003 N*2005-K.Park

  31. Dependence of S1/2 , A1/2MAID2003 N*2005-K.Park

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

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

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

  35. σLTP vs. W @ Q2=1.72GeV2, CSCM<0. N*2005-K.Park

  36. σLTP vs. W @ Q2=1.72GeV2, CSCM>0. N*2005-K.Park

  37. σLTP vs. W @ Q2=2.05GeV2, CSCM<0. N*2005-K.Park

  38. σLTP vs. W @ Q2=2.05GeV2, CSCM>0. N*2005-K.Park

  39. σLTP vs. W @ Q2=2.44GeV2, CSCM<0. N*2005-K.Park

  40. σLTP vs. W @ Q2=2.44GeV2, CSCM>0. N*2005-K.Park

  41. σLTP vs. W @ Q2=2.91GeV2, CSCM<0. N*2005-K.Park

  42. σLTP vs. W @ Q2=2.91GeV2, CSCM>0. N*2005-K.Park

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

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

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

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