Localized $4\sigma$ and $5\sigma$ Dijet Mass Excesses in ALEPH LEP2 Four-Jet Events

Understand

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 $M_1+M_2\sim 110\mbox{ GeV}$; about half of the excess is concentrated in the region $M_1\sim 80\mbox{ GeV}$, $M_2\sim 25\mbox{ GeV}$, with a local significance between $4.7\sigma$ and $5.5\sigma$, depending on assumptions about hadronization uncertainties.