Observation of the charge symmetry breaking [formula presented] reaction near threshold

E. J. Stephenson, A. D. Bacher, C. E. Allgower, A. Gårdestig, C. M. Lavelle, G. A. Miller, H. Nann, J. Olmsted, P. V. Pancella, M. A. Pickar, J. Rapaport, T. Rinckel, A. Smith, H. M. Spinka, U. van Kolck

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

We report the first observation of the charge symmetry breaking [Formula presented] reaction near threshold. Measurements using a magnetic channel (gated by two photons) of the [Formula presented] scattering angle and momentum (from time of flight) permitted reconstruction of the [Formula presented] “missing mass,” the quantity used to separate [Formula presented] events from the continuum of double radiative capture [Formula presented] events. We measured total cross sections for neutral pion production of [Formula presented] at 228.5 MeV and [Formula presented] at 231.8 MeV. The uncertainty is dominated by statistical errors. These cross sections arise fundamentally from the down-up quark mass difference and quark electromagnetic effects that contribute in part through meson mixing (e.g., [Formula presented]) mechanisms.

Original languageEnglish (US)
JournalPhysical review letters
Volume91
Issue number14
DOIs
StatePublished - 2003

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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