paper

Pole analysis on unitarized one loop PT amplitudes

arXiv:1108.1451 · doi:10.1088/0253-6102/57/5/15

Abstract

We analyze and couple channel [1,1] matrix Padé amplitudes of chiral perturbation theory. By fitting phase shift and inelasticity data, we determine pole positions in different channels (, ,, , , ) and trace their trajectories. We stress that a couple channel Breit--Wigner resonance should exhibit two poles on different Riemann sheets and meet each other on the real axis when . Poles are hence classified using this criteria and we conclude that and are unambiguous Breit--Wigner resonances. For scalars the situation is much less clear. We find that is a molecular state rather than a Breit--Wigner resonance, while , though behaves oddly when varying , does maintain a twin pole structure.

16 pages

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