  The axion-gluon coupling can be constrained directly through hard exclusive
processes at the LHC. Specifically, we study the associated production of a
long-lived axion with a $\rho^0$ meson in ultra-peripheral $AA$ collisions and
in $pp$ collisions. With the axion escaped from the detector, the final state
is characterized by a mono-hadron signature. The main background in our
analysis originates from the $\rho^0+\pi^0$ process, where the photons from the
$\pi^0$ decay are undetected due to limited detector performance. Our analysis
yields an exclusion limit of the axion-gluon coupling that is comparable to the
limit obtained from the mono-jet process at the LHC.
