Near Threshold Neutral Pion Electroproduction at High Momentum Transfers and Generalized Form Factors

Abstract

We report the measurement of near threshold neutral pion electroproduction cross sections and the extraction of the associated structure functions on the proton in the kinematic range $Q^2$ from 2 to 4.5 GeV${}^2$ and $W$ from 1.08 to 1.16 GeV. These measurements allow us to access the dominant pion-nucleon s-wave multipoles $E_{0+}$ and $S_{0+}$ in the near-threshold region. In the light-cone sum-rule framework (LCSR), these multipoles are related to the generalized form factors $G_1^{{\pi }^{0}p}(Q^2)$ and $G_2^{{\pi }^{0}p}(Q^2)$. The data are compared to these generalized form factors and the results for $G_1^{{\pi }^{0}p}(Q^2)$ are found to be in good agreement with the LCSR predictions, but the level of agreement with $G_2^{{\pi }^{0}p}(Q^2)$ is poor.

arXiv comment17 pages, 18 figures, Journal article (Physical Review C)

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• Measurement of the generalized form factors near threshold via ${\gamma }^{\ast }p\to n{\pi }^{+}$ at high $Q^2$
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Cited by in corpus (3)

• Nucleon Form Factors and Distribution Amplitudes in QCD
• Exclusive ${\mathbf{\pi }}^0\mathbf{p}$ electroproduction off protons in the resonance region at photon virtualities 0.4~GeV${}^2$ $\le {\mathbf{Q}}^2\le 1$~GeV${}^2$
• Exploring Baryon Resonances with Transition Generalized Parton Distributions: Status and Perspectives