  The production mechanism of light (anti)nuclei in heavy-ion collisions has
been extensively studied experimentally and theoretically. Two competing
(anti)nucleosynthesis models are typically used to describe light (anti)nuclei
yields and their ratios to other hadrons in heavy-ion collisions: the
statistical hadronization model (SHM) and the nucleon coalescence model. The
possibility to distinguish these phenomenological models calls for new
experimental observables. Given their large baryon number, light (anti)nuclei
have a high sensitivity to the baryon chemical potential ($\mu_{\rm B}$) of the
system created in the collision. In this talk, the first measurement of
event-by-event antideuteron number fluctuations in heavy-ion collisions is
presented and compared with expectations of the SHM and coalescence model. In
addition, the antinuclei-to-nuclei ratios are used to obtain a measurement of
$\mu_{\rm B}$ in heavy-ion collisions with unprecedented precision.
