# Exothermic Dark Matter with Light Mediator after LUX and PandaX-II in 2016

## TL;DR

This paper evaluates models of exothermic dark matter with a light mediator, incorporating recent experimental constraints, and finds that most models cannot explain the CDMS-Si signals due to stringent limits from multiple detectors.

## Contribution

It systematically analyzes isospin-violating, exothermic, and light mediator dark matter models against latest experimental data, showing their inability to account for CDMS-Si excess.

## Key findings

- Most models are excluded by LUX, PandaX-II, XENON1T, and PICO-60 data.
- Light mediator and Xe-phobic exothermic models are also strongly constrained.
- Current dark matter frameworks struggle to explain the CDMS-Si excess.

## Abstract

Dark matter (DM) direct detections are investigated for models with the following properties: isospin-violating couplings, exothermic scatterings, and/or a light mediator, with the aim to reduce the tension between the CDMS-Si positive signals and other negative searches. In particular, we focus on the non-standard effective operators which could lead to the spin-independent DM-nucleus scatterings with non-trivial dependences on the transfer momentum or DM velocity. As a result, such effective operator choices have the very mild effects on the final fittings. Furthermore, by including the latest constraints from LUX, PandaX-II, XENON1T and PICO-60, we find that, for almost all the considered models, the predicted CDMS-Si signal regions are either severely constrained or completely excluded by the LUX, PandaX-II, XENON1T and PICO-60 data, including the most promising Xe-phobic exothermic DM models with/without a light mediator. Therefore, we conclude that it is very difficult for the present DM framework to explain the CDMS-Si excess.