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BARYON FORM FACTORS

BARYON FORM FACTORS. TWO GAMMA EXCHANGE RESOLVED THE DISCREPANCY BETWEEN THE DATA OBTAINED BY ROSENBLUTH SEPARATION AND POLARIZATION TRANSFER FOR G E (p) QUALITY DATA ON N(1440), N(1535) and some higher N* TRANSITION FORM FACTORS

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BARYON FORM FACTORS

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  1. BARYON FORMFACTORS • TWO GAMMA EXCHANGE RESOLVED THE DISCREPANCY BETWEEN THE DATA OBTAINED BY ROSENBLUTH SEPARATION AND POLARIZATION TRANSFER FORGE(p) • QUALITY DATA ON N(1440), N(1535) and some higher N* TRANSITION FORM FACTORS • CONSISTENT RESULTS FOR THE STRANGENESS FORM FACTORS OF THE PROTON FROM SAMPLE, HAPPEX, A4 ANDG0. CHALLENGE FOR THEORY • CLEAR INDICATIONS FOR LONG RANGE ”PION CLOUD” IN ALL NUCLEON FORM FACTORS • PRECISION DATA ONGE(n) • NEW PRECISION DATA FORgP (p) • FORM FACTORS --- DVCS --- PARTON DISTRIBUTIONS

  2. NEXT FEW YEARS • NEW DATA ON THE FORM FACTORS IN THE TIME LIKE REGION OF Q2 • GLUON POLARIZATION • TRANSVERSITY … COMPASS-II, FAIR

  3. THEORIST’SFORM FACTORS • CALCULATE FROM CURRENT MATRIX ELEMENTS • GE(Q2) = (1+τ)1/2 <1/2, Q/2| I0| 1/2, -Q/2> • GM(Q2)= (1+1/τ)1/2 <1/2, Q/2 | Ix| 1/2, -Q/2> • τ = Q2/4 M2) • ELECTRIC FORM FACTORS IN THE BREIT FRAME • GE(Q2) = ∫ d3R eiQ·Rρ(R), • GM(Q2) =∫ d3R eiQ·R (1/2) <j, j|r × j(R) |j, j> • in the Breit frame, where Q0 = 0 • GOVERNING SINGULARITIES IN TIME-LIKE REGION

  4. EXPERIMENTALISTS FORM FACTORS:SPACE-LIKE Q2 • DIFFERENTIAL CROSS SECTION • dσ/dΩ = σM{ (GE2+τGM2) /(1+τ)+2τ GM2 tan2θ/2} • One-photon exchange approximation • forward-backward Rosenbluth separation • SPIN POLARIZATION TRANSFER • GE/GM = - ( Pt / Pl ) {(E + E’)/2 M} tan θ/2 • no forward-backward separation, but instrumental challenge

  5. EXPERIMENTALISTS FORM FACTORS:TIME-LIKE Q2 M. Mirazita et al. 2005

  6. AXIAL FORM FACTOR RELATION TO PION DECAY LO ChPT (PCAC) B. Juliá-Díaz et al., PRC 70

  7. EXOTIC FORM FACTORS • THE STRANGENESS FORM FACTORS CONTRIBUTION FROM SS- PAIRS • THE ANAPOLE FORM FACTOR AXIAL PART IN ELECTROMAGNETIC CURRENT J = … (GF/Mp2) FA(Q2)(Q2-Q Q)5 arises from PV quark interactions • TRANSVERSITY <P|q-(0) q(0)|P> » q[P S –P S]

  8. GEp/GMp EXPERIMENT I.A.Qattan et al, PRL 94, 142301 (2005)

  9. TWO PHOTON EXCHANGE P. Guichon & M. Vanderhaeghen PRL 91, 142303 (2003) Need only a 6% correction in the  dependent term in the differential cross section from TPE to resolve the discrepancy  = 1/1+2(1+) tan2 (/2)

  10. HADRONIC CALCULATIONBlunden et al, PRL 91, 142304 (2003)nucl/th&0506039 nucl-th/0506039

  11. THE (1232) CONTRIBUTIONIS SMALL !S. Kondratyuk et al, nucl-th/0506026

  12. PARTONIC CALCULATIONA.V.Afanasev et al, PRD 72,013008 (2005) Ratio of e- to e+ scattering decisive! Exp’t planned at Novosibirsk

  13. GE ON THE LATTICE ISOVECTOR FORM FACTOR C. Alexandrou (2005) PRELIMINARY

  14. GM ON THE LATTICE ISOVECTOR FORM FACTOR C. Alexandrou (2005) PRELIMINARY

  15. GE(n)

  16. LONG RANGE STRUCTURE IN THE NUCLEON FORM FACTORS J. Friedrich & Th. Walcher, EPJA A17, 607 (2003)

  17. THE PION CLOUD THE PION CLOUD J.Friedrich & Th. Walcher, EPJA A17, 607 (2003)

  18. POINCARÉ COVARIANT QUARKMODELS GENERATORS OF POINCARÉ TRANSFORMATIONS: H, P, J, K K: boosts CHOICE OF KINEMATIC SUBGROUP: INSTANT FORM KINEMATICS: P, J, K{H} O(3) LIGHT FRONT KINEMATICS: P, K, J{H} O(1,2) POINT FORM KINEMATICS: J, K, P{H} SO(1,3)

  19. SU(6) quark model for instant, point and front form kinematics: fitted wave functions B. Julia-Diaz, D.O.R & F. Coester PRC 69, 035212 (2004)

  20. BARYON PHENOMENOLOGY WITH DIFFERENT KINEMATICS B. Juliá-Díaz, F. Coester & DOR, PRC C69 (2004) 035212 SU(6) spin-isospin wave functions x (1 + P2/4 b2)-a hyperspherical momentum P = ((4/3)(p12+p22+p32))1/2

  21. GE(n) & Foldy term rn2exp= -0.1161 ± 0.0022 fm2, rn2 Foldy= -0.126 fm2 solid: instant, dotted: point dashed: front S’: 2% instant,point, 1% front Consistent quark model demands covariant treatment of the boosts 1-2% mixed symmetry S-state Sufficient to fix the qqq quark model

  22. GROUND STATE WAVE FUNCTION ANDCONFINING POTENTIAL

  23. Point form quark model form factors R.F.Wagenbrunn et al, hep-ph/0509047 Very small matter radius r2 = 0.1 fm2

  24. AXIAL & INDUCED PSEUDOSCALAR FORM FACTORS J = {GA(Q2) 5– i (Q/2 M) GP (Q2) 5}a gP(Q2) = (m/ 2 M) GP(Q2) MUON CAPTURE : Q2 = - m2

  25. PROBLEM & RESOLUTION • ChPT: gP = 8.3 § 0.2 N. Kaiser, PRC 67, 027002 (2003) • TRIUMF RMC: gP = 12.2 § 1.1 D. H. Wright, PRC 57, 373 (1998) • New result on ortho-para transition in μ- molecular H: factor 2.7 gP = 10.6 § 1.1 J.H.D. Clarke et al nucl-ex/0509025 (+ Triumf RMC) - Introduces problems with earlier data …

  26. Quark model results for GA and GP MA=1.077 § 0.039 GeV/c2 A.Liesenfeld et al, PL B 468, 20 (1999)

  27. (1232) ! N qqq quark model underestimates the transtion form factor by » 30 %  Pion cloud and/or sea-quarks

  28. – N -  COUPLED CHANNEL CALCULATION Sato-Uno-Lee PRC 67, 065201 (2003)

  29. Coupled channel \pi-N-\Delta model

  30. HADRONIC COUPLED CHANNELS -N- MODEL T. Sato and T.-S. H. Lee Nucl-th/0404025

  31. Bates, CLAS, PDG I.Aznauryuan, ANL talk 2005

  32. I.Aznauryuan, ANL talk 2005

  33. NΔ TRANSITION FORM FACTOR ACCORDING TO QCD LATTICE CALCULATION C. Alexandrou et al, PRL 94, 020601 (2005)

  34. C. Alexandrou et al., hep-lat/0509140

  35. Effective field theory NV. Pascalutsa and M. Vanderhaeghen,hep-ph/0508060

  36. N(1440) HELICITY AMPLITUDES I.Aznauryuan, ANL talk 2005 PRD C71, 015201 (2005)

  37. N(1535) HELICITY AMPLITUDESI.G.Aznauryan (CLAS), PRD C71, 015201 (2005)

  38. STRANGENESS FORM FACTORS γ, Z0

  39. E. J. Beise et al, Prog. Part. Phys. 54, 289 (2005)

  40. D. Armstrong & K.Carter, CERN Courier 45, 8 (2005) GO: PRL 95, 092001 (2005), A4: Prog.Part.Nucl.Phys. 55, 320 (2005) SAMPLE: PLB 583, 79 (2004), HAPPEX: PRC 69, 065501 (2004)

  41. BUT μs = GMs(0)SHOULD BE NEGATIVE ! ASYMMETRIC LONG RANGE FLUCTUATION … PSEUDOSCALAR MESON LOOP K+ P↑ +e -e/3 (strange quark) Λ, Σ0 < K+0|T| p> » <|¢ q| > POSITIVE MAGNETIC MOMENT CONTRIBUTION ? NO ... MULTIPLY BY – 3 (< s- |γμ| s> NEGATIVE GMs !

  42. D.Beck and R.D.McKeown, Ann Rev Nucl Part Sci 51, 189 (2001)

  43. K,K* loops in the ”chiral” quark model μs = - 0.046 nm L. Hannelius & DOR, PRC 62, 045204 (2000) • QCD Lattice calculation with chiral extrapolation μs = - 0.046 ± 0.019 nm D.B.Leinweber & al, PRL 94, 212001 (2005) ” tremendous challenge for future experiments”

  44. SPIN DEPENDENT HYPERFINE INTERACTIONLOWERS ANTISYMMETRIC SPIN STATES <S=0 | 1¢2|S=0> = -3 <S=1 | 1¢2|S=1> =+1 COLOR MAGNETIC HF INTERACTION: V= (2 / 9 m2) s1¢2(r) FLAVOR-SPIN INTERACTION ...fits the exp’t spectrum V = CijFi¢Fj i¢j , C» 30 NUCLEON: <N| i¢j|N> = -2 <| i¢ji¢j|N> = +10

  45. The is in the S-state, Not KΛ like! B.S.Zou & DOR, PRL 95, 072001 (2005)

  46. Fenice/ADONE GM(p) FOR TIME LIKE Q2 E835/FNAL M. Mirazita et al, INFN preprint (2005)

  47. GM(p) FOR TIME LIKE Q2 M. Mirazita et al, INFN preprint (2005)

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