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Survey of charge symmetry breaking operators for dd -> alpha pi0

A. Gardestig·C. J. Horowitz·A. Nogga·A. C. Fonseca·C. Hanhart·G. A. Miller·J. A. Niskanen·U. van Kolck
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Abstract

The charge-symmetry-breaking amplitudes for the recently observed d d -> alpha pi0 reaction are investigated. Chiral perturbation theory is used to classify and identify the leading-order terms. Specific forms of the related one- and two-body tree level diagrams are derived. As a first step toward a full calculation, a few tree-level two-body diagrams are evaluated at each considered order, using a simplified set of d and alpha wave functions and a plane-wave approximation for the initial dd state. The leading-order pion-exchange term is shown to be suppressed in this model because of poor overlap of the initial and final states. The higher-order one-body and short-range (heavy-meson-exchange) amplitudes provide better matching between the initial and final states and therefore contribute significantly and coherently to the cross section. The consequences this might have for a full calculation, with realistic wave functions and a more complete set of amplitudes, are discussed.

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A. Gardestig, C. J. Horowitz, A. Nogga, A. C. Fonseca, C. Hanhart, G. A. Miller, J. A. Niskanen, U. van Kolck. 2004-02-04. Survey of charge symmetry breaking operators for dd -> alpha pi0. https://doi.org/10.1103/physrevc.69.044606

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