Mixed Stops and the ATLAS on-Z Excess
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.
Cite
@article{arxiv.1508.02419,
title = {Mixed Stops and the ATLAS on-Z Excess},
author = {Jack H. Collins and Jeff Asaf Dror and Marco Farina},
journal= {arXiv preprint arXiv:1508.02419},
year = {2015}
}
Comments
11 pages, 5 figures. v3: final revision with minor additions, matches the version published on PRD