B physics results from CMS in Run 2

In this work, the most recent heavy-flavour results from the CMS Collaboration with data collected during LHC Run-2 period are presented. Firstly, the search for $\chi_{b}(3P)$ states, through their decays to $\Upsilon(3S)\gamma$, is presented. Using data corresponding to an integrated luminosity of 80 fb$^{-1}$, the $\chi_{b1}(3P)$ and $\chi_{b2}(3P)$ states have been resolved for the first time. Secondly, the search for excited $B_c^+(2S)$ states, through their decay to $B_c^+\pi^+\pi^-$, is presented. With the full Run-2 data set, corresponding to 140 fb$^{-1}$, the $B_c^+(2S)$ and $B_c^{+\,*}(2S)$ states have been resolved for the first time. Finally, the search for the charge-lepton flavour violating decay $\tau\to\mu\mu\mu$, using an integrated luminosity of 33 fb$^{-1}$, is presented. No signal has been observed and a $90\%$ confidence level upper limit on the branching fraction is set to $8.8\cdot 10^{-8}$.