Trigger Acceptance Biases on $B_{d} \to K^{*0} \mu^{+} \mu^{-}$

The rare decay $B_{d} \rightarrow K^{*0} \left( \rightarrow K^{+} \pi^{-} \right) \mu^{+} \mu^{-}$ is a promising channel for New Physics searches through modifications of the angular distribution of the final state particles. Key to performing this measurement is a good understanding of how the trigger, particle reconstruction and offline event selection bias the angular distribution. This note outlines the expected trigger performance and angular biases from different trigger lines. Studies with the LHC$\it b$ GEANT based Monte Carlo simulation indicate a total trigger efficiency of 86.7$\pm$0.2\% can be achieved for events which are fully reconstructed and pass the offline selection criteria. The most efficient single combination of trigger lines gives an efficiency of 74.2$\pm$0.2\%. The High Level Trigger has been tuned to introduce minimal angular bias compared to that which will in any case be induced by requiring that all the relevant particles are reconstructed in the LHC$\it b$ detector.