  Understanding the phase diagram of QCD by measuring fluctuations of conserved
charges in heavy-ion collision is one of the main goals of the beam energy scan
program at RHIC. Within this work, we calculate the role of hadronic
interactions and momentum cuts on cumulants of conserved charges up to fourth
order in a system in equilibrium within a hadronic transport approach (SMASH).
In our model the net baryon, net charge and net strangeness is perfectly
conserved on an event-by-event basis and the cumulants are calculated as a
function of subvolume sizes and compared to analytic expectations. We find a
modification of the kurtosis due to charge annihilation processes in systems
with simplified degrees of freedom. Furthermore the result of the full SMASH
hadron gas for the net baryon and net proton number fluctuations is presented
for systems with zero and finite values of baryon chemical potential.
Additionally we find that due to dynamical correlations the cumulants of the
net baryon number cannot easily be recovered from the net protons. Finally the
influence of deuteron cluster formation on the net proton and net baryon
fluctuations in a simplified system is shown. This analysis is important to
better understand the relation between measurements of fluctuations in
heavy-ion collisions and theoretical calculation which are often performed in a
grand canonical ensemble.
