Abstract
Electron and photon triggers covering transverse energies from 5 GeV to several TeV are essential for signal selection in a wide variety of ATLAS physics analyses to study Standard Model processes and to search for new phenomena. The ATLAS trigger system is divided in a hardware-based Level-1 trigger and a software-based high-level trigger, both of which were upgraded during the LHC shutdown in preparation for Run 2 operation. To cope with the increasing luminosity and more challenging pile-up conditions at a centre-of-mass energy of 13 TeV, the trigger selections at each level are optimised to control the rates and keep efficiencies high. To achieve this goal multivariate analysis techniques are used. The ATLAS electron and photon triggers and their performance with Run 2 data are presented.
Highlights
The ATLAS [1] electron and photon (e/γ) triggers select events with electrons and photons from the huge amount of data produced by high energy proton-proton collisions at the Large Hadron Collider [2], only a fraction of which can be recorded
Electron and photon triggers covering transverse energies from 5 GeV to several TeV are essential for signal selection in a wide variety of ATLAS physics analyses to study Standard Model processes and to search for new phenomena
W → eν was a key channel for the measurement of the W mass [3] and photon signatures played a major role in the Higgs boson discovery [4]
Summary
The ATLAS [1] electron and photon (e/γ) triggers select events with electrons and photons from the huge amount of data produced by high energy proton-proton collisions at the Large Hadron Collider [2], only a fraction of which can be recorded. Many improvements have been made in Run 2 to the e/γ triggers to maintain efficiencies at Run 1 levels for as long as possible whilst keeping the rates at a manageable level These proceedings provide a brief overview of the design and recent upgrades to the ATLAS e/γ triggers as well their performance in 2016 and 2017 data taking. 3. Upgrades to Electron and Photon Identification in Run 2 In 2017 the LHC is producing collisions at greater rates and with higher than ever average pileup per bunch crossing. Upgrades to Electron and Photon Identification in Run 2 In 2017 the LHC is producing collisions at greater rates and with higher than ever average pileup per bunch crossing These conditions have prompted a number of innovative upgrades to the trigger algorithms, with the aim of reducing the trigger rate without compromising the efficiency in order to reduce and delay the need to increase trigger ET thresholds.
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