Extraction of Beam-Spin Asymmetries from the Hard Exclusive π
Phys Rev Lett
; 125(18): 182001, 2020 Oct 30.
Article
in En
| MEDLINE
| ID: mdl-33196236
ABSTRACT
We have measured beam-spin asymmetries to extract the sinÏ moment A_{LU}^{sinÏ} from the hard exclusive e[over â]pâe^{'}nπ^{+} reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center of mass. The A_{LU}^{sinÏ} moment has been measured up to 6.6 GeV^{2} in -t, covering the kinematic regimes of generalized parton distributions (GPD) and baryon-to-meson transition distribution amplitudes (TDA) at the same time. The experimental results in very forward kinematics demonstrate the sensitivity to chiral-odd and chiral-even GPDs. In very backward kinematics where the TDA framework is applicable, we found A_{LU}^{sinÏ} to be negative, while a sign change was observed near 90° in the center of mass. The unique results presented in this Letter will provide critical constraints to establish reaction mechanisms that can help to further develop the GPD and TDA frameworks.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Phys Rev Lett
Year:
2020
Document type:
Article
Affiliation country:
United States