ATLAS on-Z Excess Through Vector-Like Quarks

TL;DR

This paper proposes that the ATLAS Z + jets + missing energy excess could be explained by pair-produced vector-like quarks decaying to Z bosons and first-generation quarks, fitting within certain mass and branching ratio ranges.

Contribution

It introduces a vector-like quark model as an explanation for the ATLAS excess, fitting the data while avoiding other experimental constraints.

Findings

The excess can be explained within 2σ level with specific vector-like quark parameters.

Preferred mass range for the quark is 610-760 GeV.

Branching ratio to Z and quark is greater than 0.3-0.45.

Abstract

We investigate the possibility that the excess observed in the leptonic-$Z +$jets $+\slashed{E}_T$ ATLAS SUSY search is due to pair productions of a vector-like quark $U$ decaying to the first-generation quarks and $Z$ boson. We find that the excess can be explained within the 2$\sigma$ (up to 1.4$\sigma$) level while evading the constraints from the other LHC searches. The preferred range of the mass and branching ratio are $610 < m_{U} < 760$ GeV and ${\rm Br}(U \rightarrow Z q) > 0.3$-$0.45$, respectively.