You can hide but you have to run: direct detection with vector mediators

TL;DR

This paper investigates how the evolution of couplings in vector mediator models affects direct detection bounds for dark matter, emphasizing the importance of including these effects for accurate interpretations.

Contribution

It introduces a comprehensive analysis of coupling running effects in vector mediator dark matter models and provides tools for incorporating these effects in future research.

Findings

Inclusion of coupling running can change bounds by several orders of magnitude.

Operator mixing at low energy significantly impacts direct detection constraints.

Tools and code are provided for easy implementation of running effects.

Abstract

We study direct detection in simplified models of Dark Matter (DM) in which interactions with Standard Model (SM) fermions are mediated by a heavy vector boson. We consider fully general, gauge-invariant couplings between the SM, the mediator and both scalar and fermion DM. We account for the evolution of the couplings between the energy scale of the mediator mass and the nuclear energy scale. This running arises from virtual effects of SM particles and its inclusion is not optional. We compare bounds on the mediator mass from direct detection experiments with and without accounting for the running. In some cases the inclusion of these effects changes the bounds by several orders of magnitude, as a consequence of operator mixing which generates new interactions at low energy. We also highlight the importance of these effects when translating LHC limits on the mediator mass into bounds on the direct detection cross section. For an axial-vector mediator, the running can alter the derived bounds on the spin-dependent DM-nucleon cross section by a factor of two or more. Finally, we provide tools to facilitate the inclusion of these effects in future studies: general approximate expressions for the low energy couplings and a public code runDM to evolve the couplings between arbitrary energy scales.