Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s $$ \sqrt{s} $$ = 8 TeV with the ATLAS detector

G. Aad, B. Abbott, J. Abdallah, S. Abdel Khalek, O. Abdinov, R. Aben, B. Abi, M. Abolins, O. S. AbouZeid, H. Abramowicz, H. Abreu, R. Abreu (+2871 others)
2014 Journal of High Energy Physics  
The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1 fb^-1 of proton-proton collision data at √(s)=8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t̃→ t χ̃_1^0 or t̃→ bχ̃_1^±→ b W^(∗)χ̃_1^0, where χ̃_1^0 (χ̃_1^±) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and
more » ... or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t̃→ t χ̃_1^0. For a branching fraction of 100 χ̃_1^0 masses below 30 GeV. For a branching fraction of 50 either t̃→ t χ̃_1^0 or t̃→ bχ̃_1^±, and assuming the χ̃_1^± mass to be twice the χ̃_1^0 mass, top squark masses in the range 250-550 GeV are excluded for χ̃_1^0 masses below 60 GeV.
doi:10.1007/jhep09(2014)015 fatcat:z7q67rzct5furcu5s73yk3o4uu