Color-Octet-Electroweak-Doublet Scalars and the CDF Dijet Anomaly

TL;DR

This paper explores how color-octet scalars could explain the CDF dijet anomaly, proposing a model consistent with electroweak data and minimal flavor violation that predicts specific collider signatures.

Contribution

It introduces a novel scenario involving color-octet scalars with a specific mass spectrum and flavor structure to account for the CDF W+jj excess, aligning with experimental constraints.

Findings

The model explains the W+jj excess via neutral scalar decay.

No significant gamma+jj excess is predicted.

The scenario is consistent with electroweak precision data.

Abstract

We study the phenomenology of color-octet scalars in the (8, 2)1/2 representation in the context of the 3.2\sigma excess, in the dijet invariant mass spectrum of the W+jj final state, recently observed by the CDF collaboration. We consider the region of parameter space with a sizable mass splitting between the charged and neutral color-octet scalars and consistent with electroweak precision data. We implement the principle of Minimal Flavor Violation (MFV) in order to suppress FCNC currents and reduce the number of free parameters. The excess in the W+jj channel corresponds to the charged current decay of the heavier neutral octet scalar into its lighter charged partner which decays into the two jets. In the MFV scenario, the production of the neutral color-octet is dominated by gluon fusion due to the Yukawa suppression of production via initial state quarks. As a result, no visible excess is expected in the \gamma+jj channel due to Yukawa and CKM suppression. Contributions to the Z+jj final state are suppressed for a mass spectrum where the decay of the heavier color-octet to this final state is mediated by an off-shell neutral color-octet partner. MFV allows one to control fraction of bottom quarks in the final state jets by a single ratio of two free parameters.