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GPD E from Transverse SSA

Ds 2s. ep ep g. s + - s - s + + s -. A =. =. x = x B /(2-x B ). k = t/4M 2. GPD E from Transverse SSA. Unpolarized beam, transverse target:. Ds UT ~ sin f {k(F 2 H – F 1 E ) + …. . }d f. Requires: Good knowledge of H …. Background: p 0.

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GPD E from Transverse SSA

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  1. Ds 2s ep epg s+ - s- s+ + s- A = = x = xB/(2-xB) k = t/4M2 GPD E from Transverse SSA Unpolarized beam, transverse target: DsUT~ sinf{k(F2H – F1E) + …..}df Requires: Good knowledge of H ….. Background: p0 Global analysis of polarized and unpolarized data needed for precision measurements

  2. Ds 2s ep epg s+ - s- s+ + s- -t F1 F2 H H E A = = 0.1 0.81 1.34 1.90 0.65 0.76 0.3 0.56 0.82 1.24 0.44 0.46 0.5 0.42 0.54 0.88 0.32 0.31 0.7 0.33 0.38 0.66 0.24 0.21 x = xB/(2-xB) k = t/4M2 GPD E from beam SSA Polarized beam, unpolarized target: x=0.3,t=-0.3 ~ ~ DsLU~ sinf{F1H+ x(F1+F2)H+kF2E}df 2-5% Kinematically suppressed, requires: Precision measurement of H,H~ large t, small x ……. Background: p0

  3. Q2=5 GeV2 GPD E form Exclusiver0transverse target 2D (Im(AB*))/p T AUT = - |A|2(1-x2) - |B|2(x2+t/4m2) - Re(AB*)2x2 A ~ 2Hu + Hd r0 B ~ 2Eu + Ed A~ Hu - Hd B ~ Eu - Ed r+ Eu, Edneeded for angular momentum sum rule. r0 K. Goeke, M.V. Polyakov, M. Vanderhaeghen, 2001 B

  4. OAM sensitive observables in exclusive production? H. Avakian, QCD’N 2006,June 14, 2006 • DVCS • DVMP • Link between GPDs and TMDs?

  5. 1 1 1 [ ] ò = - J G = x + x J q xdx H q( x , , 0 ) E q( x , , 0 ) 2 2 - 1 X. Ji, Phy.Rev.Lett.78,610(1997) Quark Angular Momentum Sum Rule GPDs Hu, Hd, Eu, Edprovide access to total quark contribution to proton angular momentum. ½ = ½ (Du+Dd+Ds) + Lq + Jg Proton’s spin J q Large x contributions important.

  6. L = 1x1035 T = 2000 hrs DQ2 = 1 GeV2 Dx = 0.05 CLAS12- DVCS/BH Beam Asymmetry e p epg E = 11 GeV DsLU~sinfIm{F1H+..}df Sensitive to GPDH Selected Kinematics

  7. CLAS12-DVCS/BH Target Asymmetry e p epg Transversely polarized target Sample kinematics E = 11 GeV Q2=2.2 GeV2, xB = 0.25, -t = 0.5GeV2 DsUT~ sinfIm{k1(F2H– F1E) +…}df AUTx Target polarization in scattering plane AUTy Target polarization perpendicular to scattering plane • Asymmetry highly sensitive to the u-quark contributions to the proton spin.

  8. CLAS12-DVCS/BH Target Asymmetry L = 2x1035 cm-2s-1 T = 1000 hrs DQ2 = 1GeV2 Dx = 0.05 e p epg E = 11 GeV Longitudinally polarized target ~ Ds~sinfIm{F1H+x(F1+F2)H...}df CLAS preliminary AUL E=5.75 GeV <Q2> = 2.0GeV2 <x> = 0.2 <-t> = 0.25GeV2

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