Study of Generalized Parton Distribu � ons at Je ff erson Lab for LIGHT CONE 2016 September 05, 2016 Andrey Kim University of Connec � cut
2 Introduc � on Deeply virtual exclusive reac � ons such as photon or π 0 meson produc � on with large gamma virtuality S xP Q 2 are key processes to probe the complex internal r T structure of nucleon and access informa � on about quark posi � on and angular momentum distribu � ons from experimental observables. Two main processes can be used to access this informa � on experimentally: Deeply Virtual Compton Sca � ering and Deeply Virtual Meson Produc � on LIGHT CONE 2016
3 Generalized parton distribu � ons HARD EXCLUSIVE PROCESSES Elas � c Sca � ering Deep Inelas � c Sca � ering Correla � on between quark longitudinal momentum and Form factors Parton distribu � ons transverse spa � al distribu � ons LIGHT CONE 2016
4 Generalized parton distribu � ons parton helicity conserving (chiral-even) GPDs parton helicity- fl ip (chiral-odd) GPDs The GPDs depend on three kinema � c variables: e.g. average parton momentum transfer momentum frac � on between ini � al and (skewness) di ff erence between fi nal nucleons the ini � al and fi nal frac � ons of the longitudinal momentum carried by the struck parton LIGHT CONE 2016
5 Exclusive processes at JLab at 6 GeV ✦ Hall A and Hall B (CLAS) at 6 GeV H1, ZEUS H1, ZEUS ✦ par � ally: complimentary, overlapping ✦ Hall A: high accuracy limited kinema � cs ✦ Hall B: wide kinema � c range limited accuracy ✦ The roadmap: 0.7 ✦ Early results (2001) from non-dedicated experiment (CLAS) ✦ First round of dedicated experiments in Halls A/B in 2004/2005 ✦ Second round in 2008-2010 ✦ Compeling exclusive program in Halls A/B at 12 GeV LIGHT CONE 2016
6 DVCS experimental observables unpolarized terms DVCS: beam polarized target polarized double polarized LIGHT CONE 2016
7 Deeply virtual Compton sca � ering Unpolarized cross sec � ons, unpolarized beam and target Polarized beam and Unpolarized target (BSA) Unpolarized beam and Polarized target (TSA) Polarized beam and Polarized target (DSA) LIGHT CONE 2016
8 DVCS cross sec � ons First round experiment at Hall A: E00-110 E00-110 DVCS cross sec � on (nb/GeV 4 ) 0.02 beam helicity-dependent Total fit 0 -0.02 0.1 beam helicity-independent E00-110 2 |BH+ DVCS| 2 |BH| 2 2 |BH+ DVCS| - |BH| 0.05 0 90 180 270 90 180 270 90 180 270 90 180 270 φ (deg) φ (deg) φ (deg) PRL 97 :262002 (2006), C. Munoz Camacho et al. (Hall A collabora � on) LIGHT CONE 2016
9 DVCS scaling test First round experiment at Hall A: E00-110 ✦ Q 2 independence: ✦ Twist-2 dominance (GPDs) curve is from VGG model calcula � ons (Vanderhaeghen, Guichon, Guidal) 2 2 Q = 1.5 GeV 2 2 Q = 1.9 GeV 2 2 Q = 2.3 GeV VGG model integrated over t PRL 97 :262002 (2006), C. Munoz Camacho et al. (Hall A collabora � on) LIGHT CONE 2016
10 DVCS beam spin asymmetries C EBAF L arge A cceptance S pectrometer First round experiment at Hall B: E01-113 2 2 VGG model: Vanderhaeghen,Guichon,Guidal Q (GeV ) JLab Hall A VGG twist-3 results A LU on the proton 4 VGG twist-2 Q 2 =2.8 Q 2 =3.3 3 A LU x B =0.45 x B =0.46 0.3 2 -t= 0.28 GeV 0.2 2 0.2 Q 2 =3.7 0.1 x B =0.46 0 1 0 Q 2 =2.3 Q 2 =2.7 Q 2 =3.0 0.1 0.2 0.3 0.4 0.5 x B =0.35 x B =0.36 x B =0.36 0.3 x -0.2 B 0.2 0.1 A LU 0 2 -t= 0.49 GeV Q 2 =1.7 Q 2 =1.9 Q 2 =2.2 0.2 0.3 x B =0.25 x B =0.25 x B =0.25 0.2 0 0.1 VGG twist-2 -0.2 0 VGG twist-3 Q 2 =1.2 Q 2 =1.4 Q 2 =1.6 0.3 x B =0.13 x B =0.17 x B =0.18 0 0 90 90 180 180 270 360 270 360 0.2 φ φ (deg) (deg) 0.1 0 0 0.5 1 1.5 0 0 0.5 1 1.5 0 0 0.5 1 1.5 PRL 100 :162002 (2008) F.X. Girod et al. (CLAS collaboration) LIGHT CONE 2016
11 DVCS kinema � c coverage at CLAS C EBAF L arge A cceptance S pectrometer First round experiment at Hall B: E01-113 DVCS cross sec � on measurements plots by H.S. Jo 21 bins in ( , x ) � B e 9 bins in t 24 bins in � 4 Extraction d σ 4 4 � � d σ d σ ep ep � 1 γ � ep ep ep ep � � � γ γ of 4-fold � 2 � � dQ dx dtd Φ 2 2 dQ dx dtd Φ dQ dx dtd Φ 2 cross sections B � � B B LIGHT CONE 2016
12 DVCS cross sec � ons C EBAF L arge A cceptance S pectrometer First round experiment at Hall B: E01-113 KMS VGG Measurements in a LARGE kinema � c domain KM10 (Kumericki, Mueller) KM10a PRL115:212003 (2015) H.S. Jo et al. (CLAS collaboration) LIGHT CONE 2016
13 DVCS cross sec � ons fi t C EBAF L arge A cceptance S pectrometer VGG First round experiment at Hall B: E01-113 2 2 2 2 2 2 2 2 2 2 2 2 Q Q = = 1.11GeV 1.11GeV Q Q = = 1.63 GeV 1.63 GeV Q Q = = 2.23 GeV 2.23 GeV x x = = 0.126 0.126 x x = = 0.185 0.185 x x = = 0.335 0.335 B B B B B B � � � 6 A = 5.30 0.95 6 A = 4.98 0.56 6 A = 1.44 1.25 1 1 1 5 5 5 � � � b = 4.25 0.98 b = 3.03 0.55 b = 1.04 3.68 1 1 1 4 4 4 Im 3 3 3 H 2 2 2 1 1 1 0 0 0 -1 -1 -1 0.5 0.5 0.5 6 6 6 4 Re 2 H 0 -2 -4 0.1 0.2 0.3 0.4 0.5 0.1 0.2 0.3 0.4 0.5 0.1 0.2 0.3 0.4 0.5 2 2 2 -t (GeV ) -t (GeV ) -t (GeV ) PRL115:212003 (2015) H.S. Jo et al. (CLAS collaboration) LIGHT CONE 2016
14 DVCS target spin asymmetries C EBAF L arge A cceptance S pectrometer Non-dedicated experiment at Hall B (longitudinally polarized target) 0.4 VGG model First measurements of VGG model DVCS target spin asymmetry: 0.2 ✦ non-dedicated experiment ✦ no Inner Calorimeter -0.2 -0.4 exclusivity 250 -0.6 2500 0 50 100 150 200 250 300 350 200 0.5 2000 Events 0.4 150 1500 0.3 0.2 100 1000 0.1 50 500 -0.1 0 0 -0.4 -0.2 0 0.2 0.4 -0.2 0 0.2 0.4 -0.2 0.2 0.3 0.4 0.15 0.2 0.25 PRL 97 :072002 (2006) S. Chen et al. (CLAS collaboration) LIGHT CONE 2016
15 DVCS target spin asymmetries C EBAF L arge A cceptance S pectrometer Second round experiment at Hall B: E05-114 (longitudinally polarized target) 0.4 0.4 0.3 0.3 GGL 0.2 0.2 KMM12 GK 0.1 0.1 VGG 0 0 This Work CLAS 2006 HERMES 2010 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 0 0 0 0.4 0.4 0.8 0.8 1.2 1.2 1.6 0 0 0.4 0.4 0.8 0.8 1.2 1.2 1.6 0 0 0.4 0.4 0.8 0.8 1.2 1.2 PRL 114 :032001 (2015) E. Seder et al. (CLAS collaboration) LIGHT CONE 2016
16 DVCS Compton form factors C EBAF L arge A cceptance S pectrometer Second round experiment at Hall B: E05-114 (longitudinally polarized target) 4 2.5 2 .5 3.5 2 2 3 2.5 1.5 1 .5 2 1 1 1.5 1 0.5 0 .5 0.5 0 0 0 0.2 0.2 0.4 0.4 0.6 0.6 0.8 0.8 1 1 1.2 1.2 3 1 2 .5 0.8 2 0.6 ❏ sensi � vity 1 .5 0.4 ❏ wide kinema � c coverage 1 0.2 ❏ improved precision 0 .5 0 0 -0.2 0.2 0.2 0.4 0.4 0.6 0.6 0.8 0.8 1 1 1.2 1.2 0.2 0.4 0.6 0.8 1 1.2 PRD 91 :052014 (2015) S. Pisano et al. (CLAS collaboration) LIGHT CONE 2016
17 Deeply virtual meson produc � on e' e ❖ Quark fl avor decomposi � on: Generalized Form Factor ❖ Flavor ra � os: cancella � on of higher twist e ff ects LIGHT CONE 2016
18 DVMP structure func � ons unpolarized terms longitudinally longitudinally polarized beam polarized target B longitudinally polarized beam M and longitudinally polarized target LIGHT CONE 2016
19 DVMP structure func � ons unpolarized terms longitudinally longitudinally polarized beam polarized target longitudinally polarized beam and longitudinally polarized target LIGHT CONE 2016
20 DVMP structure func � ons unpolarized terms longitudinally longitudinally polarized beam polarized target 300 200 longitudinally polarized beam 100 and longitudinally polarized target 0 0 100 200 300 LIGHT CONE 2016
21 DV π 0 P beam spin asymmetries C EBAF L arge A cceptance S pectrometer First round experiment at Hall B: E01-113 Two-photon invariant mass 0.2 0.2 0.2 0.15 25000 Counts/0.002 GeV 0.15 0.15 IC IC-EC EC-IC EC 0.1 0.1 0.1 α 0.05 0.05 20000 0.05 4 0 0 0 -0.05 -0.05 0.2 15000 -0.05 0.15 0 0.5 1 1.5 � 30 � 30 � 30 0.1 0.2 0.15 10000 0.05 0.1 0.05 0 0 3 -0.05 0.2 -0.05 0.2 5000 0.15 0.15 0.1 0.1 0.05 0.2 0 0.15 0 0.05 0.1 0.2 0.3 0.1 0.2 0.3 0.1 0.2 0.3 0.1 0.2 0.3 -0.05 0.2 0.1 IM ( γ γ ) (GeV) 0.15 0 0.05 0.1 0 -0.05 0.05 -0.05 0.2 0 0.15 2 -0.05 0.2 0.1 0.15 0.05 0 0.1 0.15 -0.05 0.2 0.05 0.1 0.15 0 0.05 0.1 0 -0.05 -0.05 0.05 0.2 0.15 0 0.15 0.1 0.1 -0.05 0.05 0.05 0 0 1 -0.05 -0.05 0.1 0.2 0.3 0.4 0.5 R. De Masi et al. Measurement of ep->ep π 0 beam spin asymmetries above the resonance region. Phys.Rev., C77:042201, 2008. PRC 77 :042201 (2008), R. De Masi et al. (CLAS collabora � on) LIGHT CONE 2016
22 DV π 0 P cross sec � ons First round experiment at Hall A: E00-110 kinema � c coverage 0.8 ) 2 (GeV 2.6 2 2 0.6 M < 1.15 GeV X 2 2.4 Q 0.4 2.2 2 2 0.2 Q = 1.9 GeV 2 2 (a) Q = 2.3 GeV 1.8 0 0 0.05 0.1 0.15 0.2 1 1.6 0.28 0.3 0.32 0.34 0.36 0.38 0.4 0.42 0.44 x B Leading twist predicts: 0.5 (b) but: 0 0 0.05 0.1 0.15 0.2 2 t -t (GeV ) m in is likely to dominate at these Q 2 but L/T separa � on is necessary PRC 83 :025125 (2011), E. Fuchey et al. (Hall A collabora � on) LIGHT CONE 2016
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