Pileup subtraction using jet areas

A bstract: One ofthe m ajorchallenges forthe LHC willbe to extract precise inform ation from hadronicnalstates in the presence ofthe large num ber ofadditionalsoft pp collisions,pileup, thatoccursim ultaneously with any hard interaction in high lum inosity runs.W e propose a novel technique,based on jetareas,thatprovidesjet-by-jetcorrectionsforpileup and underlying-event eects.Itisdata driven,doesnotdepend on M onteCarlo m odelling and can beused with any jet algorithm forwhich a jetarea can besensibly dened.W e illustrate itseectivenessforsom e key processesandnd thatitcan beapplied also in the contextofthe Tevatron,low-lum inosity LHC and LHC heavy-ion collisions.