Measurement of CP observables in semileptonic decays at LHCb

LHCb has recorded large samples of semileptonic {\textit B} decays. These provide the possibility to study {\textit CP} violation effects in the $B^{0}_s$ and $B^{0}$ systems. Decay-time-integrated or decay-time-dependent asymmetries between charge conjugated final states probe {\textit CP} violation in $B^{0}_{(s)}$ mixing through the measurement of the parameter $a_{\textrm sl}. These measurements rely on data-driven techniques to control possible detection asymmetries.