First analysis of the space charge effects on a third order coupled resonance

The effect of space charge on bunches stored for long term in a nonlinear lattice can be severe for beam survival. This may be the case in projects as SIS100 at GSI or LIU at CERN. In 2012, for the first time, the effect of space charge on a normal third order coupled resonance was investigated at the CERN-PS. The experimental results have highlighted an unprecedented asymmetric beam response: in the vertical plane the beam exhibits a thick halo, while the horizontal profile has only core growth. The quest for explaining these results requires a journey through the 4 dimensional dynamics of the coupled resonance investigating the fixed-lines, and requires a detailed code-experiment benchmarking also including beam profile benchmarking. This proceeding gives a short summary of the experimental results of the 2012 PS measurements, and address an interpretation based on the dynamics the fixed-lines.