Decay properties of $b$-hadrons with the ATLAS experiment

Recent results of the ATLAS experiment at LHC on decay properties of $b$-hadrons are reviewed. The time-dependent $CP$ asymmetry parameters have been measured in $B^0_s\rightarrow J/\psi \phi$ decays using flavour tagging. The parity-violating decay asymmetry parameter $\alpha_b$ and the helicity amplitudes have been measured for the decay $\Lambda^0_b\rightarrow J/\psi\Lambda^0$. The branching fraction ${\cal B}(B^+\rightarrow \chi_{c1}K^+)$ has been measured with $\chi_{c1}$ reconstruction in the decay $\chi_{c1} \rightarrow J/\psi \gamma$. An excited $B^\pm_c$ state has been observed through its decays to the ground $B^\pm_c$ state and two oppositely charged pions. The mass and decay of this state are consistent with expectations for the second $S$-wave state of the $B^\pm_c$ meson, $B^\pm_c(2S)$