Hollow cone sieve for top

A method of top tagging is introduced. Using the anti-kt algorithm to define jets, events with nj=2 fat jets of cone size R=1.5 are decomposed into R=0.6 subjets and retained if nj(R=0.6) ⩾4. One pair of subjets reconstructs the W mass and another two subjets are tagged as a b-jet, as necessary for hadronic or semileptonic events of tt¯ origin. This “hollow cone” method distinguishes the tt¯ events from the light parton QCD dijet events. Our simulations are made for the LHC at 7 TeV. The sieve allows for top identification at lower pT than other proposed methods and thus allows a higher signal retention.