  In general, the constituents of the bulk matter produced in heavy-ion
collisions carry, besides electric charge, multiple other conserved quantum
numbers like baryon number and strangeness. Therefore, an electric field will
not only generate an electric current but, at the same time, also currents in
baryon number and strangeness. We propose that the impact of the electric field
on these conserved currents should be characterized by additional transport
coefficients, which we call cross-conductivities. In this paper, we introduce
and present a calculation of these cross-conductivities from the Green-Kubo
formalism within the transport code SMASH for different chemical compositions
of hadron resonance gases. We find that the coefficients underlie an ordering
in the active degrees of freedom and that thus the chemical composition of the
system plays a crucial role. Further, we argue that in future comparisons of
lattice QCD calculations with these findings, one could constrain which degrees
of freedom and their corresponding charge properties are relevant for the QCD
dynamics of the system.
