Adding supersymmetry to the model predicts the existence of a fermionic superpartner for the axion, the axino, and a bosonic superpartner, the saxion. They are all bundled up in a chiral superfield.
Incorporating supersymmetry into the model suggests the existence of a fermionic superpartner, the axino, and a bosonic superpartner, the saxion, alongside the axion. These particles are all contained within a chiral superfield.