The beam spin asymmetry of the exclusive pseudoscalar channel was measured for the first time in the deep-inelastic regime ( and ) using a longitudinally polarized 5.78 GeV electron beam at Jefferson Lab with the CEBAF Large Acceptance Spectrometer. The data were accumulated in 144 four-dimensional bins of , , −t and ϕ over a wide kinematic range, where ϕ is the azimuthal angle between the lepton and hadron scattering planes, The measured azimuthal dependence with large amplitudes of the moments is a clear indication of a substantial contribution to the polarized cross-section from transversely polarized virtual photons. In the framework of generalized parton distributions (GPDs) this contribution is expressed via longitudinal-transverse interference between chiral-even and chiral-odd GPDs. The experimental results are compared to the existing theoretical models demonstrating the sensitivity to the product of chiral-odd and chiral-even GPDs and provide new constraints to the existing GPD parameterizations.
Zhao, B., Kim, A., Joo, K., Bedlinskiy, I., Kim, W., Kubarovsky, V., et al. (2019). Measurement of the beam spin asymmetry of e→p→e′p′η in the deep-inelastic regime with CLAS. PHYSICS LETTERS. SECTION B, 789, 426-431 [10.1016/j.physletb.2018.12.065].
Measurement of the beam spin asymmetry of e→p→e′p′η in the deep-inelastic regime with CLAS
D'Angelo A.Membro del Collaboration Group
;Lanza L.;Rizzo A.Membro del Collaboration Group
;
2019-02-10
Abstract
The beam spin asymmetry of the exclusive pseudoscalar channel was measured for the first time in the deep-inelastic regime ( and ) using a longitudinally polarized 5.78 GeV electron beam at Jefferson Lab with the CEBAF Large Acceptance Spectrometer. The data were accumulated in 144 four-dimensional bins of , , −t and ϕ over a wide kinematic range, where ϕ is the azimuthal angle between the lepton and hadron scattering planes, The measured azimuthal dependence with large amplitudes of the moments is a clear indication of a substantial contribution to the polarized cross-section from transversely polarized virtual photons. In the framework of generalized parton distributions (GPDs) this contribution is expressed via longitudinal-transverse interference between chiral-even and chiral-odd GPDs. The experimental results are compared to the existing theoretical models demonstrating the sensitivity to the product of chiral-odd and chiral-even GPDs and provide new constraints to the existing GPD parameterizations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
