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arXiv · 2112.03355

Pole position of the $a_1(1260)$ resonance in a three-body unitary framework

Daniel Sadasivan·Andrei Alexandru·Hakan Akdag·Felipe Amorim·Ruairí Brett·Chris Culver·Michael Döring·Frank X. Lee·Maxim Mai
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Abstract

Masses, widths, and branching ratios of hadronic resonances are quantified by their pole positions and residues with respect to transition amplitudes on the Riemann sheets of the complex energy-plane. In this study we discuss the analytic structure in the physical energy region of three-body scattering amplitudes on such manifolds. As an application, we determine the pole position of the $a_1(1260)$ meson from the ALEPH experiment by allowing for $\pi\rho$ coupled channels in S- and D-wave. We find it to be $\sqrt{s_0}=(1232^{+15+9}_{-0-11}-i266^{+0+15}_{-22-27})~\text{MeV}$.

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Daniel Sadasivan, Andrei Alexandru, Hakan Akdag, Felipe Amorim, Ruairí Brett, Chris Culver, Michael Döring, Frank X. Lee, Maxim Mai. 2021-12-06. Pole position of the $a_1(1260)$ resonance in a three-body unitary framework. https://doi.org/10.1103/physrevd.105.054020

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