Measurement of beam asymmetry for π- Δ++ photoproduction on the proton at Eγ=8.5 GeV

The GlueX Collaboration

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We report a measurement of the π- photoproduction beam asymmetry for the reaction γp→π-Δ++ using data from the GlueX experiment in the photon beam energy range 8.2-8.8 GeV. The asymmetry ς is measured as a function of four-momentum transfer t to the Δ++ and compared to phenomenological models. We find that ς varies as a function of t: negative at smaller values and positive at higher values of |t|. The reaction can be described theoretically by t-channel particle exchange requiring pseudoscalar, vector, and tensor intermediaries. In particular, this reaction requires charge exchange, allowing us to probe pion exchange and the significance of higher-order corrections to one-pion exchange at low momentum transfer. Constraining production mechanisms of conventional mesons may aid in the search for and study of unconventional mesons. This is the first measurement of the process at this energy.

Original languageEnglish
Article numberL022201
JournalPhysical Review C
Issue number2
Publication statusPublished - Feb 2021

Bibliographical note

Funding Information:
This work was supported by the U.S. Department of Energy Office of Nuclear Physics under Award No. DE-FG02-05ER41374. We recognize additional support by the Natural Sciences and Engineering Research Council of Canada Grant No. SAPPJ-2018-00021. We acknowledge in particular input from from V. Mathieu to this work, as well as productive discussions with A. Szczepaniak, J. Nys, V. Mathieu, M. Mikhasenko, and B.-G. Yu. We would also like to acknowledge the outstanding efforts of the staff of the Accelerator and the Physics Divisions at Jefferson Lab that made the experiment possible. This work was also supported in part by the U.S. Department of Energy, the U.S. National Science Foundation, the German Research Foundation, GSI Helmholtzzentrum für Schwerionenforschung GmbH, the Russian Foundation for Basic Research, the UK Science and Technology Facilities Council, the Chilean Comisión Nacional de Investigación Científica y Tecnológica, the National Natural Science Foundation of China, and the China Scholarship Council. This material is based on work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC05-06OR23177.

Publisher Copyright:
© 2021 American Physical Society.

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