Measurement of {\textit 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 $B_s^0$ and $B^0$ systems. Decay-time-integrated or decay-time-dependent asymmetries between charge conjugated final states probe {\textit CP} violation in $B_{(s)}^0$ mixing through the measurement of the parameter $a_{\textrm sl}. These measurements rely on data-driven techniques to control possible detection asymmetries.