  We study the spin dynamics of the Resonant Excitonic State (RES) proposed,
within the theory of an emergent SU(2) symmetry, to explain some properties of
the pseudo-gap phase of cuprate superconductors. The RES can be described as a
proliferation of particle-hole patches with an internal modulated structure. We
model the RES modes as a charge order with multiple $2{\bf {p}}_{\text{F}}$
ordering vectors, where $2{\bf {p}}_{\text{F}}$ connects two opposite side of
the Fermi surface. This simple modelization enables us to propose a
comprehensive study of the collective mode observed at the antiferromagnetic
(AF) wave vector $\mathbf{Q}=(\pi,\pi)$ by Inelastic Neutron Scattering (INS)
in both superconducting state (SC), but also in the Pseudogap regime. In this
regime, we show that the dynamic spin susceptibility accuses a loss of
coherence terms except at special wave vectors commensurate with the lattice.
We argue that this phenomenon could explain the change of the spin response
shape around $\mathbf{Q}$. We demonstrate that the hole dependence of the RES
spin dynamics is in agreement with the experimental data in
HgBa$_{2}$CuO$_{4+\delta}$.
