Muon trigger performance with the reoptimised LHCb detector

We study the performance of the level-0 muon trigger with the reoptimised LHCb detector corresponding to the configuration used for the trigger TDR. This is an update of the LHCb note 2002-041 describing the trigger performance with the LHCb "classic" detector. The low-energy background has been updated to this new detector configuration, as well as the LHC machine induced background. The reference samples used to compute the L0 muon efficiency are the data selected by the offline analysis. The efficiency to select Bs ->J/psi phi events is 88% for single muon output rate of 125 kHz after the pile-up and the multiplicity cuts. We also study the evolution of the performance when running conditions degrade. In the worst case, the muon trigger signal efficiency decreases by ~15% demonstrating the robustness of the muon trigger.