The trigger systems of the LHC detectors play a crucial role in determining the
physics capabilities of the experiments. A reduction of several orders of
magnitude of the event rate is needed to reach values compatible with the
detector readout, offline storage and analysis capabilities. The CMS experiment
has been designed with a two-level trigger system: the Level 1 (L1) Trigger,
implemented on custom-designed electronics, and the High Level Trigger (HLT), a
streamlined version of the CMS reconstruction and analysis software running on a
Here we will present the design and performance of the main muon, electron and
photon triggers, in view of the more challenging conditions for the LHC Run 2.
For the muon case, we will discuss the improvement of local drift tube and
cathode strip chamber reconstruction, standalone muon tracking and silicon
tracking+standalone combined muon reconstruction. For the electron/photon case,
we will discuss the deployment of new local electromagnetic calorimeter
reconstruction and improvements on the object identification and isolation.