Standard model explanation of a CDF dijet excess in Wjj

TL;DR

This paper explains the CDF Wjj dijet excess as a statistical fluctuation from single-top-quark production, showing that background subtraction methods can induce apparent peaks in the spectrum.

Contribution

It provides a standard model explanation for the CDF dijet excess, attributing it to background fluctuations rather than new physics.

Findings

CDF's dijet excess can be explained by single-top-quark production fluctuations.

D0's data is consistent with a small fluctuation, supporting the background explanation.

The peak arises from the background subtraction method used by CDF.

Abstract

We demonstrate the recent observation of a peak in the dijet invariant mass of the Wjj signal observed by the CDF Collaboration can be explained as the same upward fluctuation observed by CDF in single-top-quark production. In general, both t-channel and s-channel single-top-quark production produce kinematically induced peaks in the dijet spectrum. Since CDF used a Monte Carlo simulation to subtract the single-top backgrounds instead of data, a peak in the dijet spectrum is expected. The D0 Collaboration has a small upward fluctuation in their published t-channel data; and hence we predict they would see at most a small peak in the dijet invariant mass spectrum of Wjj if they follow the same procedure as CDF.