The CMS High Level Trigger

[摘要] The CMS experiment has been designed with a two-level trigger system: the Level-1 Trigger, implemented in custom-designed electronics, and the High-Level Trigger (HLT), a streamlined version of the CMS offline reconstruction software running on a computer farm. A software trigger system requires a tradeoff between the complexity of the algorithms running with the available computing power, the sustainable output rate, and the selection efficiency. We present the performance of the main triggers used during the 2012 data taking, ranging from simple single-object selections to more complex algorithms combining different objects, and applying analysis-level reconstruction and selection. We discuss the optimisation of the trigger and the specific techniques to cope with the increasing LHC pile-up, reducing its impact on the physics performance.

[发布机构] Northeastern University, 111 Dana Research Center, 360 Huntington Ave, Boston; MA; 02115, United States^1

[效力级别] 计算机科学 [学科分类] 计算机科学（综合）

[关键词] Complex algorithms;Computing power;High-level triggers;Level-1 triggers;Optimisations;Reconstruction software;Single object;Trigger systems