Speaker
Description
The sigma resonance has been a long standing puzzle in both, theory and experiment. Because its non-Breit Wigner shape, the extraction of its properties is not straightforward. Dispersive analysis techniques are needed to extract the properties of the resonance. Lately, several lattice data groups have performed a calculation of phase shifts for $\pi \pi$ scattering in the Isospin = 0, Spin = 0 channel. Unitary Chiral Perturbation Theory provides a framework which is based in chiral symmetry and unitarity constraints useful to extract the properties of resonances from the lattice. The formalism is implemented in the finite volume to analyse the energy levels extracted from the lattice data. Then, the pion mass dependence is investigated providing extrapolations to the physical point.
