Study of the structure of hadrons using beam and target polarization observables with CLAS AKA Overview of the eg1- dvcs results

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1 Study of the structure of hadrons using beam and target polarization observables with CLAS AKA Overview of the eg- dvcs results Angela Biselli CLAS5 the 4th European CLAS workshop Catania, Italy, February 7-5

2 Some open questions on hadronic structure Can we describe nucleons in terms of its constituents Where does the spin of the nucleon come from? CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 Courtesy of A. Bacchetta

3 5 Dimensional Structure of the nucleon Wigner distributions ρ(x,b T,k T) Transverse momentum Transverse position Longitudinal momentum partons Transverse plane Courtesy of A. Bacchetta CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 3

4 Nucleon distributions Wigner distributions ρ(x,b T,k T) polarization observables TMD transverse- SIDIS momentum distributions (x,k T) Elastic ep FF Form Factors (Δ T) PDF parton distribution functions (x) DIS - DIHADRON integral over x Impact parameter distributions (x,b T) d Fourier transform b T GPD Generalized parton DVCS - DVMP distributions (x,ξ=,δ T) CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 Courtesy of A. Bacchetta 4

eg- dvcs run Polarized electron beam ~85% Polarized target NH3 ~8% ND3 ~4% CLAS+

9) Hydrogen target NH 3 Beam energy: 5.89 & 4.735 GeV Luminosity:.

967 GeV Luminosity: 5.7 fb Target position: - 67.

5 eg- dvcs run Polarized electron beam ~85% Polarized target NH3 ~8% ND3 ~4% CLAS+ Inner calorimeter (IC) Part A (Feb.- Mar. 9) Part B (Apr.- Jun. 9) Part C (Aug.- Sep. 9) Hydrogen target NH 3 Beam energy: 5.89 & GeV Luminosity:.7 fb Target position: cm Hydrogen target NH 3 Beam energy: GeV Luminosity: 5.7 fb Target position: cm Deuteron target ND 3 Beam energy: GeV Luminosity: 5.3 fb Target position: cm CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5

6 Summary of eg- dvcs analyses and status Analysis Authors Status Single and double spin asymmetries for Deeply Virtual Compton Scattering on Longitudinally Polarized Proton Target Single and Double Spin Asymmetries for Deeply Virtual Exclusive π Production on Longitudinally Polarized Proton Target Biselli, Niccolai, Pisano, Seder E. Seder et al Phys. Rev. Lett. 4 (5) 3 PRD: S. Pisano et al arxiv: ACCEPTED A. Kim Ad Hoc review Measurement of Single and Double Spin Asymmetries in Semi- Inclusive Deep Inelastic Scattering on Proton and Deuteron S Koirala Analysis note review Target and beam spin asymmetries for di- hadron production ep eʹ π + π X S. Anefalos Pereira In progress DVCS beam and target spin asymmetries on the neutron target D. Sokhan In progress Spin Asymmetries in exclusive π +, π, η, and π - electro- production from the eg- DVCS experiment Precision measurements of g of the proton and the deuteron with 6 GeV electrons P. Bosted Y. Prok Analysis note approved Y. Prok et al Phys.Rev. C9 (4), 5 CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 6

$ep Compton Form Factors: 8 GPDs related quantities Z apple <ef = P dx x F (x,,t) x + =mf = [F (,,t) F (,,t)] F (x,,t) x longitudinal quark momentum fraction ξ longitudinal momentum transfer to the$

7 Single and double spin asymmetries GP Ds F H, H,E,Ẽ = x B t =(p p ) + t Q x B + x B t Q for DVCS on proton target ep! ep Compton Form Factors: 8 GPDs related quantities Z apple <ef = P dx x F (x,,t) x + =mf = [F (,,t) F (,,t)] F (x,,t) x longitudinal quark momentum fraction ξ longitudinal momentum transfer to the struck quark t momentum transfer to the nucleon CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 7

DVCS Polarization observables Asymmetries interference BH & DVCS e γ φ e leptonic plane hadronic plane p Beam Spin Asymmetry A LU A LU ( ) /=m[f H + (F + F ) e H Target Spin Asymmetry A UL t 4M F

8 DVCS Polarization observables Asymmetries interference BH & DVCS e γ φ e leptonic plane hadronic plane p Beam Spin Asymmetry A LU A LU ( ) /=m[f H + (F + F ) e H Target Spin Asymmetry A UL t 4M F E]sin A UL ( ) /=m[f e H + (F + F )(H + x B E) (x B F + t 4M F ) e E]sin Double Spin Asymmetry A LL A LL ( ) /<e[f e H + (F + F )(H + x B E) (x B F + t 4M F ) e E](A + B cos ) CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 8

9 eg- DVCS highlights High statistics, improvement of a factor over previous target asymmetry measurement (S. Chen et al) Complete detection of the final state - >small nuclear background Large kinematic range Simultaneous measurement of all three Beam, Target, and Double spin asymmetries in the same kinematic range A UL simultaneous fit Compton Form Factors S. Chen et al Phys. Rev. Lett. 97, φ Degree Observable CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 Sensitivity to CFFs Experiment 9 Notes Δσ beam (p) Im H p Hall A High statistics, limited coverage, 4 dimensional (Q,x,- t,φ) A LU (p) Im H p HERMES CLAS High statistics and coverage, 4 dimensional (Q,x,- t,φ) Δσ beam (n) Im E n Hall A One (Q,x b) bin, 7 - t bins, low statistics, high systematics A UL (p) Im H p,im H p HERMES CLAS Low statistics integrated over 3/4 variables A LL (p) Re H p,re H p HERMES Low statistics integrated over 3/4 variables A UT (p) Im H p, Im E p HERMES Low statistics integrated over 3/4 variables

10 A UL Target Spin Asymmetries for DVCS <Q >=.5(GeV/c) <x B >=.79 <Q >=.97(GeV/c) <x B >=.55 <Q >=.4(GeV/c) <x B >=.55 <Q >=.6(GeV/c) <x B >=.345 Data Fit VGG systematic E. Seder et al Phys. Rev. Lett. 4 (5) t (GeV/c). > (*) <Q = 3.3(GeV/c) <x B > =.453 (*) (*) (GeV/c) Q -t (GeV/c) 5 (Q,x b ) bins x 4 - t bins φ(deg) x B CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5

11 α UL Target Spin Asymmetries for DVCS <Q > =.5 (GeV/c) <x B > =.79 <Q > =.4 (GeV/c) <x B > =.55 <Q > = 3.3 (GeV/c) <x B > =.453 E. Seder et al Phys. Rev. Lett. 4 (5) 3 a(t).3.. <Q > =.97 (GeV/c) <x B > =.55 <Q > =.6 (GeV/c) <x B > =.345 This Work CLAS 6. Q = 3.7 x B =.46 HERMES Q =.8 = t (GeV/c) CLAS5 4th European CLAS workshop,. Catania,. Italy, February. 6-5 x B Q =.3 =.35 x B Q =.7 =.5.3 x B Q =. =.3.3 x B Q = 3.3 =.46.3 x B Q =.7 =.36 x B Q =.9 =.5.3 x B Q =.4 =.7.3 x B.... Q = 3. x B =.36 Q =. x B = A UL = UL sin + cos Agreement with Hermes & CLAS Weaker drop in - t than A UL Axial charge Im H A LU is more concentrated than electric charge ImH A LU Q =.6 x B =.8 -t (GeV ) Qualitative agreement VGG Alternatively, description of the process in terms of meson & GK (or more low generally t Regge trajectory) exchanges has been attempted [4, 8]. DVCS may be viewed as ρ production Good followed agreement by ρ-γ coupling in vacuum KMM or in the but nucleon field. In addition to pole contributions in the t channel [9], the box diagram that takes into account ρ- nucleon t<q intermediate /4 states has been evaluated [4]. This Models calculation, represented by the dashed curves in Figs. 3 and 4, is in fair agreement with our results up to Q - - VGG Vanderhaeghen, Guidal, =.3 GeV. The significance of this dual description (Regge Guichon vs. handbag) remains to be fully investigated. In summary,. GK the Goloskokov, most extensive set Kroll of DVCS data to date has been KMM obtainedkumericki, with the CLAS spectrometer, Müller, Murray augmented with specially designed small-angle photon calorimeter GGL and solenoid. Gonzalez, Beam-spin Goldstein, asymmetries were Liuti extracted in the valence quark region, as a function of all variables describing the reaction. Present parameterizations of GPDs describe reasonably well, but not perfectly, the main features of the data. The measured kinematic dependences will put stringent constraints on any DVCS model, and in particular on the generalized parton dis-

12 A LU t (GeV/c) > =.5(GeV/c) <Q > =.79 <x B > =.97(GeV/c) <Q > =.55 <x B > =.4(GeV/c) <Q > =.55 <x B > =.6(GeV/c) <Q > =.345 <x B data fit to data VGG KMM systematics Beam Spin Asymmetries for DVCS <Q > = 3.3(GeV/c) <x B > = Φ (deg) 3 Φ (deg) S. Pisano et al arxiv: PRD Accepted 3 Φ (deg) α LU <Q > =.5 (GeV/c) <x B > =.79 <Q > =.4 (GeV/c) <x B > =.55 <Q > = 3.3 (GeV/c) <x B > = t (GeV/c) <Q > =.97 (GeV/c) <x B > =.55 <Q > =.6 (GeV/c) <x B > = data -t (GeV/c) VGG KMM GK GGL CLAS A LU on H Agreement with CLAS on H No sensitivity to nuclear effects Sensitivity to Im H p Fast drop in - t Good agreement KMM but t<q /4 Good agreement GL in some bins VGG & GK overestimate A LU = LU sin + cos CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5

13 A LL.5 S. Pisano et al arxiv: PRD Accepted -t (GeV/c) > =.5(GeV/c) <Q > =.79 <x B > =.97(GeV/c) <Q > =.55 <x B > =.4(GeV/c) <Q > =.55 <x B > =.6(GeV/c) <Q > =.345 <x B Double Spin Asymmetries for DVCS κ LL <Q > =.5 (GeV/c) <x B > =.79 <Q > =.4 (GeV/c) <x B > =.55 <Q > = 3.3 (GeV/c) <x B > = t (GeV/c) <Q > =.97 (GeV/c) <x B > =.55 <Q > =.6 (GeV/c) <x B > = data -t (GeV/c) VGG KMM GK GGL BH λ LL Constant term dominated by BH cosφ term small and dominated by BH Agreement with VGG, GK, KMM <Q > =.5 (GeV/c) <x B > =.79 <Q > =.4 (GeV/c) <x B > =.55 <Q > =.97 (GeV/c) <x B > =.55 <Q > =.6 (GeV/c) <x B > =.345 data fit to data VGG KMM BH systematics <Q > = 3.3(GeV/c) <x B > =.453 A LL = k LL + LL cos + cos <Q > = 3.3 (GeV/c) <x B > = data -t (GeV/c) VGG KMM GK GGL BH 3 Φ (deg) 3 Φ (deg) 3 Φ (deg).5.5 -t (GeV/c) CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 3

Compton Form Factors H Im, H ~ Im H Im, H ~ Im H Im, H ~ Im 4 3.5 3.5.5.5 <Q > =.5 (GeV/c) <x B > =.79.5 <Q > =.4 (GeV/c) <x B > =.55.5.5.8.6.4. -...4 -t.6 (GeV.8 ).

453 H Im, fit to present data H ~ Im, fit to present data H Im, fit to [3] and [5] H ~ Im, fit to [3] and [5] CLAS5 4th European CLAS workshop, Catania, Italy, February

A 37, 39 (8) Local fitting at each experimental Q,x B,t Quasi model- independent: bounding the domains of variation of the CFFs (5xVGG) 8 unknowns, non linear problem,

14 Compton Form Factors H Im, H ~ Im H Im, H ~ Im H Im, H ~ Im <Q > =.5 (GeV/c) <x B > =.79.5 <Q > =.4 (GeV/c) <x B > = t.6 (GeV.8 ). H Im, H ~ Im H Im, H ~ Im.5.5 S. Pisano et al arxiv: PRD Accepted <Q > =.97 (GeV/c) <x B > =.55 <Q > =.6 (GeV/c) <x B > =.345 <Q > = 3.3 (GeV/c) <x B> =.453 H Im, fit to present data H ~ Im, fit to present data H Im, fit to [3] and [5] H ~ Im, fit to [3] and [5] CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 M. Guidal, Eur. Phys. J. A 37, 39 (8) Local fitting at each experimental Q,x B,t Quasi model- independent: bounding the domains of variation of the CFFs (5xVGG) 8 unknowns, non linear problem, strong correlations Mostly sensitive to Im H ImH has a steeper slope than Im H - axial charge more concentrated? Slope of ImH decreasing as x b increases - fast quarks (valence) more concentrated in the nucleon s center, slow quarks (sea) more spread out Not enough A LL statistical precision to extract real parts Re H Re E 4

15 DVCS Beam and Target spin asymmetries on the neutron target en! en Pioneering CLAS measurement ndvcs important for flavor separation (H, E) u (,,t)=9/5[4(h, E) p (,,t) (H, E) n (,,t)] (H, E) d (,,t)=9/5[4(h, E) n (,,t) (H, E) p (,,t)] A LU on neutron needed to constrain E n, together with E p (from A UT ) and H p,n we can extract the quark angular momentum (Ji s sum rule) ndvcs selection cut J q = J G = Z + D. Sokhan xdx[h q (x,, ) + E q (x,, )] BSA CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 5

16 Single and Double Spin Asymmetries for Deeply Virtual Exclusive π A. Kim ep! ep 8 GP Ds F H q, H q,e q, Ẽq H q T, H q T,Eq T, Ẽq T CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 parton helicity-conserving (chiral- even) parton helicity-flip (chiral-odd) For the π Fi =(e u Fi u e d Fi d )/ p 6

17 Single and Double Spin Asymmetries for Deeply Virtual Exclusive π d 4 A. Kim dq dx B dtd = T + L + TT cos + p ( + ) LT cos +P t ( p ( + ) sin UL +P b p ( ) LT sin sin + sin UL sin ) +P b P t ( p LL + p ( ) cos LL cos ) hf i = X Z dxh,µ (x,,q,t)f (x,,t) M B A sin LU A sin UL Im[hH T i hẽi] Im[hĒT i h Hi + hh T i hẽi] A const LL h H T i A cos LL Re[hĒT i h Hi + hh T i hẽi] CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 7

18 Target Spin Asymmetries for ep- >epπ Azimuthal dependence of TARGET spin asymmetries in different kinema c bins Entries 3 A. Kim χ distribu on of different kinema cs fits.5.5 Entries Mean.9446 RMS.35 PRELIMINARY CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 8

19 Double Spin Asymmetries for ep- >epπ.5 Azimuthal dependence of DOUBLE spin A. asymmetries Kim in different kinema c bins χ distribu on of different kinema cs fits Entries.5.5 PRELIMINARY CLAS5 4th European CLAS workshop, Catania, Italy, February Entries Mean.9446 RMS PRELIMINARY

20 A. Kim Double Spin Asymmetries for ep- >epπ PRELIMINARY Curves Goloskokov- Kroll.5.5 CLAS5 4th European CLAS workshop, Catania, Italy, February

21 Measurement of Single and Double Spin Asymmetries in Semi- Inclusive DIS Leading twist TMD q/h U L T U f h S. Koirala en! e X e e P h FF q/h U L T U D H L g L h L T f T g T A UL = N + N fp t N + + N A LL = h,h T / Asin UL N + N fd (y)p b P t N + + N / g D f D, FF sin + Asin UL sin g well known from the collinear case (DIS), its P h dependence only recently explored N PDF X L G L H L T H G T H, H T A sin UL only term at LEADING ORDER involves h? L Hermes ~ zero related to transverse polarization of quarks in the longitudinal target Non-zero in CLAS (Avakian PRL 5, 6 () CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5

22 Target Spin Asymmetries for ep- >eπx π+ π - π S. Koirala π+ π - π. x (.,.) (.,.3) B x B. x (.,.) (.,.3) B x B.. sinφ A UL sinφ A UL x (.3,.39) (.39,.48) B x B -. x (.3,.39) (.39,.48) B x B.. sinφ A UL sinφ A UL P h [GeV] P h [GeV] P h [GeV] P h [GeV] CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5

23 Double Spin Asymmetries for ep- >eπx S. Koirala π+ π - π π+ π - π.5 x (.,.) (.,.3) B x B.5 x (.,.) (.,.3) B x B Const A LL cosφ A LL x (.3,.39) (.39,.48) B x B.5 x (.3,.39) (.39,.48) B x B Const A LL cosφ A LL P h [GeV] P h [GeV] P h [GeV] P h [GeV] CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 3

Target and beam spin asymmetries for di- hadron production Higher- twist PDF q/h U L T U f

e + X e N PDF S Anefalos Pereira e P h FF P h X DiFF H ^q chiral- odd interference

Experimental status f (x),g (x), and g T (x) measured through DIS h (x): transversity

24 Target and beam spin asymmetries for di- hadron production Higher- twist PDF q/h U L T U f (x) e(x) L g (x) h L (x) T g T (x) h (x) ep! e + X e N PDF S Anefalos Pereira e P h FF P h X DiFF H ^q chiral- odd interference fragmenta~on func~on extracted by the Belle Collabora~on from e + /e - data PRD 85, 43 () Experimental status f (x),g (x), and g T (x) measured through DIS h (x): transversity distribution - chiral odd. Can be accessed only with Semi- Inclusive DIS e(x), and h L (x) still unknown CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 4

25 Target and beam spin asymmetries for F UU,T = xf q (x)dq (z,cos,m h) F cos F sin F sin di- hadron production S Anefalos Pereira ep! e + X Accessing higher twist PDFs with polarization experiments R sin R UU = x Q z f q (x) D^q (z,cos,m h ) apple R sin R M LU = x xe q (x) Q M H ^q (z,cos,mh )+ ~ in the Wandzura- Wilczek approx h z f q (x) G^q (z,cos,m h ) apple R sin R M UL = x xh q L Q M (x) H ^q (z,cos,mh )+ h z gq (x) G^q (z,cos,m h ) F const LL = xg q (x)dq (z,cos,m h) R sin Q F cos R LL = x z gq (x) D^q (z,cos,m h ) e(x) and h L (x) related to quark- gluon correlations e(x) x- integral related to scalar- charge of the nucleon h L (x) x- integral related to the nucleon tensor charge Beam Asymmetry Target Asymmetry Double Spin Asymmetry CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 5

26 Results beam asymmetry for ep- >eπ + π - X A LU e(x) H (z, cosθ, M h ) S Anefalos Pereira Pisano (ef) Two independent analysis Significant non- zero asymmetry Agreement with ef analysis (Pisano) A LU / e q (x) H ^q (z,cos,mh ) CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 6

27 Results target asymmetry for ep- >eπ + π - X A LU e(x) H (z, cosθ, M h ) S Anefalos Pereira Two independent analysis Non zero sinφ sin φ compatible with zero significantly non-zero asymmetries A UL / h q L (x) H ^q (z,cos,mh ) CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 7

28 Results double spin asymmetry for ep- >eπ + π - X S Anefalos Pereira ( + ) t +( + ) t Non zero const term Significantly non-zero A const asymmetries A const LL / g q (x)d q (z,cos,m h ) A cos R LL / g q (x) D ^q (z,cos,mh ) CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 8

29 Precision measurements of g of the proton and the deuteron with 6 GeV d "+/"* apple F d de = M + tan Y. Prok et al Phys.Rev. C9 (4), 5 en! ex F, F unpolarized structure functions F M ± tan (E + E cos Q g M M g ) g, g polarized structure functions A (,Q,y)= d "+ d "* d "+ + d "* g F = A D C g g quark Δq, antiquark Δq - and gluon ΔG g (x, Q ) pqcd = X apple e q ( q + q) + s(q ) C q + s(q ) G C G N f CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 9

30 Precision measurements of g of the proton and the deuteron with 6 GeV Proton Y. Prok et al Phys.Rev. C9 (4), 5 en! ex Deuteron 3 This data egb SLAC W=GeV pqcd LSS have stronger Q dependence pqcd above data at at low x, below at higher x new global fit will constrain higher twist correction CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 and improve ΔG : (Color online) Results for g /F as a function of Q for the proton in nine bins of x. A bin centering correction has pplied to the data points in this plot, of the form g F (x c,q )/ g F (x, Q ), where x c is the value of x at the center of the nd x and Q are the experimental averages over the size of the bin. The present results are shown as the large black solid 3 pqcd LSS positive ΔG pqcd LSS negative ΔG

31 Spin Asymmetries in exclusive π +, π, topology ep! e + n η, and π - electro- production final state particles electron, +, neutron ep! e ( )p electron, two photons, proton ep! e ( )p electron, two photons, proton en! e p electron,, proton ep! e + (n) electron, + ep! e ( )p ep! e ( )p en! e (p) ep! e electron, one photon, proton electron, one photon, proton electron, ( )(p) electron, two photons ep! e ( )(p) electron, two photons P. Bosted Comprehensive study of exclusive meson production Resonance region Main motivation: global fit for radiative to semi- inclusive meson production Topologies combined to maximize statistics Kinematic range:. < W <3 GeV < Q < 6 GeV = ( + P b A LU + P t A UL + P b P t A LL ) CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 3

32 Maid 7 Double Spin Asymmetry results P. Bosted Averaged over φ * ep- >en π + have some significantly negative values, particularly in the region.7 <W < GeV, w the MAID model is large and positive in this region. We speculate that the data seem possibly indicate some strength from resonances near.8 to GeV, producing smal even negative asymmetries in that region. A full unitary isobar fit to all available dat required to verify this hypothesis, however. ep- >epη en- >ep π- CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 FIG. 35: Same as Fig. 33 except for the reaction ep! e p, and the use of only three and two Q bins. The MAID model is actually for the p final state. Results in the deep region W> GeV Extension of the DV π P analysis by A. Kim Disagreement at high W in the resonance region First beam target asymmetries for η Agreement W<.5 GeV thanks to existing cross section data Beam- target asymmetries for π + and π - results from egb and eg4 not published (yet!) Beam- target asymmetries for π results from egb only at beam energy of.6 GeV The results for the p final state are shown in Fig. 37. The results are mos or consistent with zero, and are consistent with the MAID 7 fit at backward smaller in magnitude than the fit at forward angles. We speculate that this ma the strong influence of the negatively polarized d quarks in this channel. 3 6 ep- >ep π

33 Maid 7 Target Asymmetry results P. Bosted Averaged over φ * ep- >en π + ep- >epη en- >ep π- Results in the deep region W> GeV Extension of the DV π P analysis by A. Kim Disagreement with MAID, esp. at high Q Consistent with π Biselli et al First target asymmetries for η CLAS5 4th European CLAS workshop, Catania, Italy, February 6-5 FIG. 4: Same as Fig. 38 except for the reaction ep! e ( )p, and the use of only ep- >ep π th bins and two Q bins. The MAID model shown is for the p final state. The result be rather similar to the results. positive, and in rough agreement with the MAID 7 fit for this channel. B. Asymmetries in the Deep Region Sensitivity to interference between. pbackground channel and resonance contributions target asymmetries for π + and π - results from egb and eg4 not published (yet!) Beam- target asymmetries for π results from egb only at beam energy of.6 GeV 33 FIG. 4: Same as Fig. 4 except for the reaction en! e p. In order to examine asymmetries in the deep GPD region, the data were re-b only two bins in x (corresponding to x<.3 and x>.3), as was done in th of Andrey Kim [7] for the p final state. Only bins with W> GeV and Q were kept. The original six bins in cos( ) and bins in were retained. This

34 Conclusions Both single and double polarization observables Inclusive, semi- inclusive and exclusive channels Large kinetic range in x,q, W, t Enough precision to extract some quantities (e.g. CFF) and to distinguish different models More data to come in CLAS CLAS experiment E- 6- E- 6- E- - 9 a E- - 3 E- 6-9 E- 6-9 PR- - 9 physics SIDIS DVCS di- hadron ndvcs DIS pol target DVCS pol target di- hadron CLAS5 4th European CLAS workshop, Catania, Italy, February

35 Thank you. Thank you to the organizers for the invitation Thank you to S. Anefalos Pereira, A. Bacchetta, P. Bosted, A. Kim,, S. Koirala, S. Niccolai, S. Pisano, Y. Prok, E. Seder, D. Sokhan

Single and double polarization asymmetries from deeply virtual exclusive π 0 electroproduction

Single and double polarization asymmetries from deeply virtual exclusive π electroproduction University of Connecticut E-mail: kenjo@jlab.org Harut Avakian, Volker Burkert et al. (CLAS collaboration) Jefferson