# Search for Light Weakly-Interacting-Massive-Particle Dark Matter by Annual Modulation Analysis with a Point-Contact Germanium Detector at the China Jinping Underground Laboratory

## TL;DR

This study uses a germanium detector at China Jinping Underground Laboratory to search for light WIMP dark matter via annual modulation, setting new limits and excluding certain parameter regions with high confidence.

## Contribution

It provides the first annual modulation analysis for light WIMPs with a germanium detector at this scale, achieving the best sensitivity below 6 GeV/c^2.

## Key findings

- Excluded DAMA/LIBRA and CoGeNT AM regions at >99.99% and 98% C.L.
- Set new upper limits on WIMP-nucleus cross sections for masses below 6 GeV/c^2.
- Achieved the most sensitive AM measurement for light WIMPs to date.

## Abstract

We present results on light weakly interacting massive particle (WIMP) searches with annual modulation (AM) analysis on data from a 1-kg mass $p$-type point-contact germanium detector of the CDEX-1B experiment at the China Jinping Underground Laboratory. Datasets with a total live time of 3.2 yr within a 4.2 yr span are analyzed with analysis threshold of 250 eVee. Limits on WIMP-nucleus (${\chi}$-$N$) spin-independent cross sections as function of WIMP mass ($m_{\chi}$) at 90\% confidence level (C.L.) are derived using the dark matter halo model. Within the context of the standard halo model, the 90\% C.L. allowed regions implied by the DAMA/LIBRA and CoGeNT AM-based analysis are excluded at $>$99.99\% and 98\% C.L., respectively. These results correspond to the best sensitivity at $m_{\chi}$$<$6$~{\rm GeV}/c^2$ among WIMP AM measurements to date.