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arXiv · 1701.08123

Measurement of the beam asymmetry $\Sigma$ for $\pi^0$ and $\eta$ photoproduction on the proton at $E_\gamma = 9$ GeV

GlueX Collaboration·H. Al Ghoul·E. G. Anassontzis·A. Austregesilo·F. Barbosa·A. Barnes·T. D. Beattie·D. W. Bennett·V. V. Berdnikov·T. Black·W. Boeglin·W. J. Briscoe·W. K. Brooks·B. E. Cannon·O. Chernyshov·E. Chudakov·V. Crede·M. M. Dalton·A. Deur·S. Dobbs·A. Dolgolenko·M. Dugger·R. Dzhygadlo·H. Egiyan·P. Eugenio·C. Fanelli·A. M. Foda·J. Frye·S. Furletov·L. Gan·A. Gasparian·A. Gerasimov·N. Gevorgyan·K. Goetzen·V. S. Goryachev·L. Guo·H. Hakobyan·J. Hardin·A. Henderson·G. M. Huber·D. G. Ireland·M. M. Ito·N. S. Jarvis·R. T. Jones·V. Kakoyan·M. Kamel·F. J. Klein·R. Kliemt·C. Kourkoumeli·S. Kuleshov·I. Kuznetsov·M. Lara·I. Larin·D. Lawrence·W. I. Levine·K. Livingston·G. J. Lolos·V. Lyubovitskij·D. Mack·P. T. Mattione·V. Matveev·M. McCaughan·M. McCracken·W. McGinley·J. McIntyre·R. Mendez·C. A. Meyer·R. Miskimen·R. E. Mitchell·F. Mokaya·K. Moriya·F. Nerling·G. Nigmatkulov·N. Ochoa·A. I. Ostrovidov·Z. Papandreou·M. Patsyuk·R. Pedroni·M. R. Pennington·L. Pentchev·K. J. Peters·E. Pooser·B. Pratt·Y. Qiang·J. Reinhold·B. G. Ritchie·L. Robison·D. Romanov·C. Salgado·R. A. Schumacher·C. Schwarz·J. Schwiening·A. Yu. Semenov·I. A. Semenova·K. K. Seth·M. R. Shepherd·E. S. Smith·D. I. Sober·A. Somov·S. Somov
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Abstract

We report measurements of the photon beam asymmetry $\Sigma$ for the reactions $\vec{\gamma}p\to p\pi^0$ and $\vec{\gamma}p\to p\eta $ from the GlueX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $\pi^0$ measurements and are the first $\eta$ measurements in this energy regime. The results are compared with theoretical predictions based on $t$-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models.

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GlueX Collaboration, H. Al Ghoul, E. G. Anassontzis, A. Austregesilo, F. Barbosa, A. Barnes, T. D. Beattie, D. W. Bennett, V. V. Berdnikov, T. Black, W. Boeglin, W. J. Briscoe, W. K. Brooks, B. E. Cannon, O. Chernyshov, E. Chudakov, V. Crede, M. M. Dalton, A. Deur, S. Dobbs, A. Dolgolenko, M. Dugger, R. Dzhygadlo, H. Egiyan, P. Eugenio, C. Fanelli, A. M. Foda, J. Frye, S. Furletov, L. Gan, A. Gasparian, A. Gerasimov, N. Gevorgyan, K. Goetzen, V. S. Goryachev, L. Guo, H. Hakobyan, J. Hardin, A. Henderson, G. M. Huber, D. G. Ireland, M. M. Ito, N. S. Jarvis, R. T. Jones, V. Kakoyan, M. Kamel, F. J. Klein, R. Kliemt, C. Kourkoumeli, S. Kuleshov, I. Kuznetsov, M. Lara, I. Larin, D. Lawrence, W. I. Levine, K. Livingston, G. J. Lolos, V. Lyubovitskij, D. Mack, P. T. Mattione, V. Matveev, M. McCaughan, M. McCracken, W. McGinley, J. McIntyre, R. Mendez, C. A. Meyer, R. Miskimen, R. E. Mitchell, F. Mokaya, K. Moriya, F. Nerling, G. Nigmatkulov, N. Ochoa, A. I. Ostrovidov, Z. Papandreou, M. Patsyuk, R. Pedroni, M. R. Pennington, L. Pentchev, K. J. Peters, E. Pooser, B. Pratt, Y. Qiang, J. Reinhold, B. G. Ritchie, L. Robison, D. Romanov, C. Salgado, R. A. Schumacher, C. Schwarz, J. Schwiening, A. Yu. Semenov, I. A. Semenova, K. K. Seth, M. R. Shepherd, E. S. Smith, D. I. Sober, A. Somov, S. Somov. 2017-01-27. Measurement of the beam asymmetry $\Sigma$ for $\pi^0$ and $\eta$ photoproduction on the proton at $E_\gamma = 9$ GeV. https://doi.org/10.1103/physrevc.95.042201

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