Phenomenological Constraints on Anomaly-Free Dark Matter Models

TL;DR

This paper explores minimal dark matter models with an anomaly-free Z' gauge boson, identifying parameter regions compatible with cosmological, collider, and direct detection constraints, and highlighting the narrow allowed parameter spaces.

Contribution

It provides a comprehensive analysis of benchmark Z' models, including Y-sequential and leptophobic types, under various experimental constraints, revealing narrow viable regions.

Findings

Vector-like Z' model is highly constrained, with a narrow allowed region near $m_\chi \simeq M_{Z'}/2$.

Axial Z' model is excluded within the studied parameter space.

Leptophobic Z' models have narrow and extended allowed regions, with $m_\chi \simeq M_{Z'}/2$ and $\log_{10}(m_\chi/\text{GeV}) \gtrsim 3.2$.

Abstract

We study minimal benchmark models of dark matter with an extra anomaly-free U(1)' gauge boson Z'. We find model parameters that give rise to the correct cosmological dark matter density while evading the latest direct detection searches for dark matter scattering produced by the XENON1T experiment, including the effects of Z-Z' mixing. We also find regions of parameter space that evade the constraints from LHC measurements of dileptons and dijets, precision electroweak measurements, and LHC searches for monojet events with missing transverse energy. We study two benchmark Z' models with Y-sequential couplings to quarks and leptons, one with a vector-like coupling to the dark matter particle and one with an axial dark matter coupling. The vector-like model is extremely tightly constrained, with only a narrow allowed strip where $m_\chi \simeq M_{Z'}/2$, and the axial model is excluded within the parameter range studied. We also consider two leptophobic Z$^\prime$ benchmark models, finding again narrow allowed strips where $m_\chi \simeq M_{Z'}/2$ as well as more extended regions where $\log_{10} (m_\chi/ {\rm GeV}) \gtrsim 3.2$.