Direct detection and CMB constraints on light DM scenario of top quark asymmetry and dijet excess at Tevatron

TL;DR

This paper investigates a model linking top quark asymmetry, light dark matter, and collider anomalies, analyzing its consistency with cosmological and experimental constraints, and predicting observable signatures in collider data.

Contribution

It provides a detailed analysis of a specific model connecting top asymmetry and light dark matter, including relic density calculations and collider predictions.

Findings

Stable light neutralino not allowed unless local DM density is lower

Dirac DM around 3 GeV may be viable and testable by Planck

Model predicts broad dijet excess and altered missing E_T distribution

Abstract

We study in detail the model by Isidori and Kamenik that is claimed to explain the top quark forward-backward asymmetry at Tevatron, provide GeV-scale dark matter (DM), and possibly improve the agreement between data and theory in Tevatron W+jj events. We compute the DM thermal relic density, the spin-independent DM-nucleon scattering cross section, and the cosmic microwave background constraints on both Dirac and Majorana neutralino DM in the parameter space that explains the top asymmetry. A stable light neutralino is not allowed unless the local DM density is 3-4 times smaller than expected, in which case Dirac DM with mass around 3 GeV may be possible, to be tested by the Planck mission. The model predicts a too broad excess in the dijet distribution and a strong modification of the missing E_T distribution in W+jj events.