If both Peccei-Quinn symmetry and supersymmetry (SUSY) are realized in nature, a new scalar particle, called the saxion, is introduced as a supersymmetric partner of the axion. The properties of the saxion are determined uniquely by SUSY and linked to those of the axion. Both particles, if they exist and are light, are produced in supernovae (SN).
In this work, we study the possibility of emission of the saxion
from SN1987A. The fact that the observed
neutrino pulse from SN1987A is in excellent agreement with the current
theory of supernovae places a strong bound on the energy loss into any
non-standard model channel, therefore enabling bounds to be placed on
the decay constant, 
, of a light saxion. The low-energy coupling
of the saxion, which couples at high energies to the QCD gauge field
strength, is expected to be enhanced from QCD scaling, making it
interesting to investigate if the saxion could place stronger bounds
on than the axion itself. Moreover, since the properties of the
saxion are determined by , a constraint on this parameter can be
translated into a constraint on the supersymmetry breaking scale. We
find that the bound on from saxion emission is comparable with
the one derived from axion emission due to a cancellation of
leading-order terms in the soft-radiation expansion.