  The effects of kinematic cuts on electric charge fluctuations in a gas of
charged particles are discussed. We consider a very transparent example of an
ideal pion gas with quantum statistics, which can be viewed as a
multi-component gas of Boltzmann particles with different charges and masses.
Cumulants of net-electric charge fluctuations $\chi_n^Q$ are calculated in a
static and expanding medium with flow parameters adjusted to the experimental
data. We show that the transverse momentum cut, $p_{t_\text{min}}\leq p_t\leq
p_{t_\text{max}}$, weakens the effects of Bose statistics, i.e. contributions
of effectively multi-charged states to higher order moments. Consequently, cuts
in $p_t$ modify the experimentally measured cumulants and their ratios. We
discuss the influence of kinematic cuts on the ratio of mean and variance of
electric charge fluctuations in a hadron resonance gas, in the light of recent
data of the STAR and PHENIX Collaborations. We find that the different momentum
cuts of $p_{t_\text{min}}=0.2$~GeV (STAR) and $p_{t_\text{min}}=0.3$~GeV
(PHENIX) are responsible for more than 30\% of the difference between these two
data sets. We argue that the $p_t$ cuts imposed on charged particles will
influence the normalized kurtosis {$\kappa_Q\sigma_Q^2 = \chi_4^Q/\chi_2^Q$} of
the electric charge fluctuations. In particular, the reduction of
$\kappa_Q\sigma_Q^2$ with increasing $p_{t_\text{min}}$ will lead to
differences between PHENIX and STAR data of ${\cal O}(6\%)$ which currently are
buried under large statistical and systematic errors. We furthermore introduce
the relation between momentum cut-off and finite volume effects, which is of
relevance for the comparison between experimental data and lattice QCD
calculations.
