Localized $4\sigma$ and $5\sigma$ Dijet Mass Excesses in ALEPH LEP2 Four-Jet Events
Abstract
We investigate an excess observed in hadronic events in the archived LEP2 ALEPH data. This excess was observed at preselection level during data-MC comparisons of four-jet events when no search was being performed. The events are clustered into four jets and paired such that the mass difference between the two dijet systems is minimized. The excess occurs in the region ; about half of the excess is concentrated in the region , , with a local significance between and , depending on assumptions about hadronization uncertainties. The other half of the events are in a broad excess near ; these display a local significance of . We investigate the effects of changing the SM QCD Monte Carlo sample, the jet-clustering algorithm, and the jet rescaling method. We find that the excess is remarkably robust under these changes, and we find no source of systematic uncertainty that can explain the excess. No analogue of the excess is seen at LEP1.
Cite
@article{arxiv.1706.02255,
title = {Localized $4\sigma$ and $5\sigma$ Dijet Mass Excesses in ALEPH LEP2 Four-Jet Events},
author = {Jennifer Kile and Julian von Wimmersperg-Toeller},
journal= {arXiv preprint arXiv:1706.02255},
year = {2018}
}
Comments
40 pages, 17 figures. Version published in JHEP. Detector section removed, S/B and SM expectation figure added, expanded discussion of hadronization uncertainties, small changes in systematic errors due to LEP1 data statistics, table added with significance as a function of center-of-mass energy, changes in text