  Structure and ordering in swarms of active particles have much in common with
condensed matter systems like magnets or liquid crystals. A number of important
characteristics of such materials can be obtained via dynamic tests such as
hysteresis. In this work, we show that dynamic hysteresis can be observed also
in swarms of active particles and possesses similar properties to the
counterparts in magnetic materials. To study the swarm dynamics, we use
computer simulations of the active Brownian particle model with dissipative
interactions. The swarm is confined to a narrow linear channel and the
one-dimensional polar order parameter is measured. In an oscillating external
field, the order parameter demonstrates dynamic hysteresis with the shape of
the loop and its area varying with the amplitude and frequency of the applied
field, swarm density and the noise intensity. We measure the scaling exponents
for the hysteresis loop area, which can be associated with the controllability
of the swarm. Although the exponents are non-universal and depend on the
system's parameters, their limiting values can be predicted using a generic
model of dynamic hysteresis. We also discuss similarities and differences
between the swarm ordering dynamics and two-dimensional magnets.
