How CMS weeds out particles that pile up – Anna Benecke (Université catholique de Louvain)
48/2-224 - Madrone
SLAC
At the LHC, in every bunch crossing not only one proton-proton interaction takes place, but several. These additional collisions are called pileup interactions. Over the past years, the increase in instantaneous luminosity of the LHC has led also to an increase in the number of pileup interactions per bunch crossing, which will reach up to 200 pileup interactions during the high-luminosity LHC operation. Removing the pileup from an event is essential, because pileup affects not only the jet energy but also other event observables such as the missing transverse momentum, jet counting, lepton isolation, and the substructure of jets. To account for these pileup effects various techniques like charged hadron subtraction, pileup jet ID, delta-beta correction for lepton isolation are used within CMS, but meanwhile a new technique, PUPPI (pileup per particle identification), has been introduced and extensively tested. This talk will explain the algorithm behind PUPPI and shows the first data-to-simulation comparisons of the variables of PUPPI as well as performance comparisons of the different pileup mitigation techniques.
Join from PC, Mac, Linux, iOS or Android: https://stanford.zoom.us/j/98973156241?pwd=cEU5RFdlVXoyc0JTeTlDMkozKzQ5UT09
Federico Bianchini, Yifan Chen
(fbianc@slac, cyifan@slac)