Beam spin asymmetry in deep and exclusive pi0 electroproduction

Abstract

The beam spin asymmetry (BSA) in the exclusive reaction ep->ep pi0 was measured with the CEBAF 5.77 GeV polarized electron beam and Large Acceptance Spectrometer(CLAS). The xB, Q2, t and phi dependences of the pi0 BSA are presented in the deep inelastic regime. The asymmetries are fitted with a sin(phi) function and their amplitudes are extracted. Overall, they are of the order of 0.04 - 0.11 and roughly independent of t. This is the signature of a non-zero longitudinal-transverse interference. The implications concerning the applicability of a formalism based on generalized parton distributions, as well as the extension of a Regge formalism at high photon virtualities, are discussed.

5 pages, 6 figures

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• Measurement of Exclusive ${\pi }^0$ Electroproduction Structure Functions and their Relationship to Transversity GPDs
• Exclusive ${\pi }^0$ electroproduction at $W>2$ GeV with CLAS
• Exclusive Neutral Pion Electroproduction in the Deeply Virtual Regime
• Unitarity constraints on neutral pion electroproduction
• Exclusive $\eta$ electroproduction at $W>2$ GeV with CLAS and transversity generalized parton distributions
• Extraction of beam-spin asymmetries from the hard exclusive ${\pi }^{+}$ channel off protons in a wide range of kinematics
• Target and Double Spin Asymmetries of Deeply Virtual ${\pi }^0$ Production with a Longitudinally Polarized Proton Target and CLAS
• Deep exclusive electroproduction of ${\pi }^0$ at high $Q^2$ in the quark valence regime
• Target and beam-target spin asymmetries in exclusive pion electroproduction for $Q^2>1$ GeV${}^2$. II. $ep\to e{\pi }^{0}p$
• Deeply Virtual Exclusive Processes and Generalized Parton Distributions
• Beam spin asymmetry in deeply virtual $\pi$ production
• Parton promenade into the nucleon