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Tree amplitudes at multiparticle threshold in a model with softly broken $O(2)$ symmetry

M. V. Libanov·V. A. Rubakov·S. V. Troitsky
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Abstract

Tree amplitudes of the production of two kinds of scalar particles at threshold from one virtual particle are calculated in a model of two scalar fields with $O(2)$ symmetric quartic interaction and unequal masses. These amplitudes exhibit interesting factorial and exponential behaviour at large multiplicities. As a by-product we observe that the kinematically allowed decay of one real particle into $n$ real particles of another kind, all at rest, has zero tree amplitude in this model for $n>2$.

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M. V. Libanov, V. A. Rubakov, S. V. Troitsky. 1993-07-02. Tree amplitudes at multiparticle threshold in a model with softly broken $O(2)$ symmetry. https://doi.org/10.1016/0550-3213(94)90394-8

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