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arXiv · 1508.02419

Mixed Stops and the ATLAS on-Z Excess

Jack H. Collins·Jeff Asaf Dror·Marco Farina
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Abstract

The ATLAS experiment has recently observed a 3-sigma excess in a channel with a leptonically decaying Z, jets, and ETmiss. It is tantalizing to interpret the signal as the first sign of a natural supersymmetric spectrum. We study such a possibility in a minimal model containing light stops and a neutralino LSP. The signal is characterized by a novel topology (compared to previous attempts) where the Z is emitted from a colored particle in the first step of a decay chain, namely t2 -> t1 Z which is characteristic of mixed stops. We show that the excess is compatible with a compressed stop spectrum and is not excluded by any other relevant search, finding some regions of parameter space with signal strength within 1-sigma of that measured by the ATLAS collaboration. In addition, we notice that the corresponding CMS search could be prone to background contamination in unexpected topologies of this kind.

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Jack H. Collins, Jeff Asaf Dror, Marco Farina. 2015-12-21. Mixed Stops and the ATLAS on-Z Excess. https://doi.org/10.1103/physrevd.92.095022

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