Search for direct pair production of supersymmetric top quarks decaying to all-hadronic final states in pp collisions at sqrt(s) = 8 TeV

TL;DR

This paper reports a search for supersymmetric top quark partners in all-hadronic final states at 8 TeV, setting new exclusion limits up to 755 GeV for certain decay modes using novel background suppression techniques.

Contribution

It introduces new background suppression and top quark reconstruction methods in the search for top squarks at the LHC.

Findings

No excess over background observed.

Excluded top squark masses up to 755 GeV.

Set limits on decay modes involving neutralinos and charginos.

Abstract

Results are reported from a search for the pair production of top squarks, the supersymmetric partners of top quarks, in final states with jets and missing transverse momentum. The data sample used in this search was collected by the CMS detector and corresponds to an integrated luminosity of 18.9 inverse femtobarns of proton-proton collisions at a centre-of-mass energy of 8 TeV produced by the LHC. The search features novel background suppression and prediction methods, including a dedicated top quark pair reconstruction algorithm. The data are found to be in agreement with the predicted backgrounds. Exclusion limits are set in simplified supersymmetry models with the top squark decaying to jets and an undetected neutralino, either via a top quark or through a bottom quark and chargino. Models with the top squark decaying via a top quark are excluded for top squark masses up to 755 GeV in the case of neutralino masses below 200 GeV. For decays via a chargino, top squark masses up to 620 GeV are excluded, depending on the masses of the chargino and neutralino.