With the planned addition of the tracking information in the Level-1 trigger in CMS for the High-Luminosity Large Hadron Collider (HL-LHC), the algorithms for the Level-1 trigger can be completely reconceptualized. Following the example for offline reconstruction in CMS to use complementary subsystem information and mitigate pileup, we explore the feasibility of using Particle Flow-like and pileup-per-particle identification techniques at the hardware trigger level. We present the challenges of adapting these algorithm to the timing and resource constraints of the Level-1 trigger, the first prototype implementations, and the expected performance on physics object reconstruction.
The CMS Level-1 Endcap Muon Trigger at the High-Luminosity LHC
