The role of the CMS electron and photon trigger in the study of the Higgs boson and high mass searches

Thomas Strebler,Cms Collaboration

doi:10.1088/1742-6596/928/1/012007

Abstract

The Compact Muon Solenoid (CMS) experiment implements a sophisticated two-level triggering system composed of the Level-1, instrumented by custom-design hardware boards, and a software High-Level-Trigger. A new Level-1 trigger architecture with improved performance is now being used to maintain the thresholds used in LHC Run I for the more challenging conditions experienced during Run II. We present the performance of the upgraded CMS electron and photon trigger in the context of Higgs boson decays into final states with photons and electrons. The calorimeter trigger system plays a central role in achieving the ambitious physics program of Run II. The upgraded trigger uses the full granularity of the calorimeters to optimally reconstruct and calibrate the electromagnetic trigger objects. It also implements combinations of calorimeter objects to provide new Level-1 quantities such as invariant mass. Optimized software selection techniques have been developed and advanced algorithms to mitigate the impact of event pileup have been implemented. The selection techniques used to trigger efficiently on these benchmark analyses will be presented, along with the strategies employed to guarantee efficient triggering for new resonances and other new physics signals involving electron/photon final states.

Highlights

In LHC experiments, a trigger system is mandatory to select events on the fly and reduce the 40 MHz collision rate to a level sustainable by the data acquisition system, typically on the order of 1 kHz
We present the performance of the upgraded Compact Muon Solenoid (CMS) electron and photon trigger in the context of Higgs boson decays into final states with photons and electrons
The development of an efficient triggering system represents a real challenge for the LHC Run II in CMS, as its physics program includes a wide variety of processes, from precision physics at the electroweak scale to the search for new physics at very high energy

Summary

Introduction

In LHC experiments, a trigger system is mandatory to select events on the fly and reduce the 40 MHz collision rate to a level sustainable by the data acquisition system, typically on the order of 1 kHz. The development of an efficient triggering system represents a real challenge for the LHC Run II in CMS, as its physics program includes a wide variety of processes, from precision physics at the electroweak scale to the search for new physics at very high energy. The Level-1 trigger bases its decision directly on coarse granularity detector readout. Its decision time is 4 μs and the L1 accept rate is kept below 100 kHz. The High-Level Trigger (HLT) benefits from full detector readout and full granularity. Its average decision time is about 200 ms and it produces on average 1 kHz of physics data

On behalf of the CMS Collaboration

Findings

Conclusion