The CMS High-Level Trigger Selection

The CMS High-Level Trigger (HLT) is designed to reduce the Level-1 accept trigger rate of 100 kHz to a final output rate of 100 Hz, at which selected events are written to permanent storage. In order to satisfy the very high performance requirements of CMS, the HLT will consist of a farm of commercial processors performing the online event filtering. The flexibility provided by a fully programmable environment implies that algorithmic changes can be easily introduced to improve the selection of various physics channels, as well as to deal with unforeseen experimental conditions. The filter farm software includes all major features of the offline reconstruction code. In this report, the selection algorithms and physics performance of the CMS HLT are presented.