Search for pair-produced third-generation squarks in compressed supersymmetric scenarios using monojet-like final states in pp collisions at $\sqrt{s} = 8$ TeV with the ATLAS detector at the LHC

Searches for third-generation squarks are reported, using 20.3 fb$^{−1}$ of proton-proton collisions at $\sqrt{s} = 8$ TeV recorded by the ATLAS experiment at the LHC. The analysis has been optimized for the stop decaying into a charm quark plus a neutralino SUSY signal and it is carried out in several signal regions differing by the requirements on the $p_T$ of the leading jet and the missing transverse energy. No excess above the Standard Model background expectation is observed. Limits are set on the visible cross-section of new physics within the requirements of the search. The results of this analysis are interpreted in terms of compressed scenarios for top squark pair production in the decay channels $\tilde{t}_1 \rightarrow c + \tilde{\chi}_1^0$ and $\tilde{t}_1 \rightarrow b + ff' + \tilde{\chi}_1^0$, and in terms of bottom squark pair production in the decay channel $\tilde{b}_1 \rightarrow b + \tilde{\chi}_1^0$. Similar exclusions are found for the nearly mass-degenerated third-generation squarks and the lightest neutralino. In particular, masses of the t ̃ and b ̃ up to 240 GeV are excluded at 95% CL, thus significantly extending the previous collider results.