Effective Theory for Light Portal Dark Matter Detection

TL;DR

This paper develops a comprehensive effective theory framework for detecting light portal dark matter, accounting for finite momentum transfer and nuclear effects, and demonstrates its application with models addressing astrophysical anomalies.

Contribution

It introduces a systematic effective theory for light portal dark matter detection, incorporating finite momentum transfer, nuclear effects, and self-interactions, with explicit models and cross section calculations.

Findings

Framework enables accurate cross section calculations for light dark matter.

Inclusion of nuclear effects improves detection predictions.

Models address astrophysical core-cusp problem through self-interactions.

Abstract

We develop a general framework for the computation of light portal dark matter direct detection, incorporating a consistent treatment of finite momentum transfer. In this framework, dark matter interacts with Standard Model matter through a light mediator, which simultaneously serves as the force carrier for dark matter self-interaction, potentially with a distinct coupling strength. The corresponding effective theory relevant for detecting this class of dark matter is systematically constructed. Our analysis focuses on light (semi)relativistic dark matter, which may originate from cosmic-ray boosting and can be probed in high threshold experiments such as large-volume neutrino detectors. In this context, the nucleon matrix elements of the effective operators at finite momentum transfer are required, made available through recent advances in lattice QCD and related nonperturbative methods. The relativistic Fermi gas model is used to convert the nucleon-level momentum transfer to the nuclear level, thereby incorporating nuclear effects pertinent to heavy target experiments. To demonstrate the utility of the framework, we present ultraviolet-complete examples featuring spin-1 and spin-2 portal dark matter. For these models, we compute the differential cross sections with respect to momentum transfer, adopting parameter choices that address the so-called core-cusp problem in astrophysical observations via dark matter self-interactions.