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Influence of the Breit-Wigner type of instability on analytic properties of partial wave amplitudes

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The relativistic binary processes are considered. For a general mass case the partial wave projection of an invariant amplitude involves some necessary continuation due to the appearance of the areas where the Mandelstam denominators vanish if the kinematical quantities have their physical values. To avoid the corresponding difficulties and to be able to perform practical and realistic calculations, the invariant amplitudes are expressed in terms of the exchanged stable and unstable objects and then they are projected onto the partial waves. In the present paper, their analytic properties in the complex energy squared plane are investigated in more detail. As the first approximation, the unstable objects are expressed in the Breit-Wigner form.

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Blažek, M. Influence of the Breit-Wigner type of instability on analytic properties of partial wave amplitudes. Czech J Phys 21, 749–767 (1971).

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  • Wave Amplitude
  • Partial Wave
  • Analytic Property
  • General Mass
  • Complex Energy