Pole position of the a1(1260) resonance in a three-body unitary framework

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. We utilize a manifestly 3-body unitary model to determine the pole position of the a1(1260) meson from the ALEPH experiment by allowing for πρ coupled channels in S- and D-wave. We find it to be (1232+15+9 −0−11 − i266+0+15 −22−27) MeV.