CMS-PAS-JME-18-001

CMS-PAS-JME-18-001
Pileup mitigation at CMS in 13 TeV data
CMS Collaboration
July 2019

Abstract: With increasing instantaneous luminosity at the Large Hadron Collider come additional reconstruction challenges. At high luminosity, many collisions occur simultaneously within one proton-proton bunch crossing. Isolating a collision of interest from the additional "pileup'' collisions is needed so as to allow for effective physics performance. In the CMS Collaboration, a number of techniques have been developed capable of mitigating the impact of these pileup collisions. Such methods include charged-hadron subtraction, pileup jet identification, neutral isospin based "$\Delta\beta$'' correction, and most recently pileup per particle identification. This note represents a survey of the performance of these techniques covering jet and missing transverse momentum reconstruction as well as lepton isolation using 35.9 and 41.4 fb$^{-1}$ of data collected with the CMS experiment in 2016 and 2017 at a center-of-mass energy of 13 TeV with up to 50 simultaneous collisions per bunch crossing. The performance of each algorithm is discussed including projections for the future, higher luminosity, running of the LHC. Significant improvements in jet energy, mass, and angular resolution, the identification of pileup jets, missing transverse momentum resolution, and lepton isolation are found.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; These preliminary results are superseded in this paper, JINST 15 (2020) P09018. The superseded preliminary plots can be found here.

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