  The first observation of the decay $\Xi^-_\mathrm{b}$ $\to$ $\psi$(2S)$\Xi^-$
and measurement of the branching ratio of $\Xi^-_\mathrm{b}$ $\to$
$\psi$(2S)$\Xi^-$ to $\Xi^-_\mathrm{b}$ $\to$ J/$\psi$$\Xi^-$ are presented.
The J/$\psi$ and $\psi$(2S) mesons are reconstructed using their dimuon decay
modes. The results are based on proton-proton colliding beam data from the LHC
collected by the CMS experiment at $\sqrt{s}$ = 13 TeV in 2016-2018,
corresponding to an integrated luminosity of 140 fb$^{-1}$. The branching
fraction ratio is measured to be $\mathcal{B}$($\Xi^-_\mathrm{b}$ $\to$
$\psi$(2S)$\Xi^-$) / $\mathcal{B}$($\Xi^-_\mathrm{b}$ $\to$ J/$\psi$$\Xi^-$) =
0.84 $^{+0.21}_{-0.19}$ (stat) $\pm$ 0.10 (syst) $\pm$ 0.02 ($\mathcal{B}$),
where the last uncertainty comes from the uncertainties in the branching
fractions of the charmonium states. New measurements of the
$\Xi_\mathrm{b}^{\ast{}0}$ baryon mass and natural width are also presented,
using the $\Xi_\mathrm{b}^-\pi^+$ final state, where the $\Xi^-_\mathrm{b}$
baryon is reconstructed through the decays J/$\psi \Xi^-$, $\psi$(2S)$\Xi^-$,
J/$\psi \Lambda$K$^-$, and J/$\psi \Sigma^0$K$^-$. Finally, the fraction of the
$\Xi^-_\mathrm{b}$ baryons produced from $\Xi_\mathrm{b}^{\ast{}0}$ decays is
determined.
