Physics Letters B
The beam spin asymmetry of the exclusive pseudoscalar channel →ep→e′p′η was measured for the first time in the deep-inelastic regime (W > 2 GeV/c2 and Q2 > 1 GeV2 /c2) 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 Q2, xB, −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 sin ϕ 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.
Original Publication Citation
Zhao, B., Kim, A., Joo, K., Bedlinskiy, I., Kim, W., Kubarovsky, V., . . . Zhao, Z. W. (2019). Measurement of the beam spin asymmetry of →ep→e′p′η in the deep-inelastic regime with CLAS. Physics Letters B, 789, 426-431. doi:10.1016/j.physletb.2018.12.065
Zhao, B.; Kim, A.; Joo, K.; Bedlinskiy, I .; Kim, W.; Kubarovsky, V.; Ungaro, M.; Gavalian, G.; Klein, A.; Kuhn, S. E.; and CLAS Collaboration, "Measurement of the Beam Spin Asymmetry of →ep → e'p'η in the Deep-Inelastic Regime with CLAS" (2019). Physics Faculty Publications. 356.