  This paper studies the dynamics of scalar particle production, focusing on
the presence of multiple fields and couplings in the medium. The interplay of
various fields and couplings can influence the production rate, potentially
overshadowing the effect of electrons alone. The plasma mixing, which induces
the resonance and screening of scalar processes, is shown to be modified by the
in-medium effects depending on the type of processes and field contents.
Incorporating these in-medium effects into the analysis of stellar cooling via
scalar emission allows for the emergence of various features of multi-field
effects given in several types of scalar models.
