Dark Matter Annual Modulation Analysis with Combined Nuclear and Electron Recoil Channels

Abstract

After decades of experimental efforts, the DAMA/LIBRA(DL) annual modulation (AM) analysis on the $\chi N$ (WIMP Dark Matter interactions on nucleus) channel remains the only one which can be interpreted as positive signatures. This has been refuted by numerous time-integrated (TI) and AM analysis. It has been shown that $\chi e$ (WIMP interactions with electrons) alone is not compatible with the DL AM data. We expand the investigations by performing an AM analysis with the addition of $\chi e$ long-range and short-range interactions to $\chi N$, derived using the Frozen Core Approximation method. Two scenarios are considered, where the $\chi N$ and $\chi e$ processes are due to a single $\chi$ ($\Gamma^{1 \chi}_{tot}$) or two different $\chi$'s ($\Gamma^{2 \chi}_{tot}$). The combined fits with $\chi N$ and $\chi e$ provide stronger significance to the DL AM data which are compatible with the presence of additional physical effects beyond $\chi N$ alone. This is the first analysis which explores how $\chi e$ AM can play a role in DL AM. The revised allowed regions as well as the exclusion contours from the other null AM experiments are presented. All DL AM allowed parameter spaces in $\chi N$ and $\chi e$ channels under both $\Gamma^{1 \chi}_{tot}$ and $\Gamma^{2 \chi}_{tot}$ are excluded at the 90\% confidence level by the combined null AM results. It can be projected that DL-allowed parameter spaces from generic models with interactions induced by two-WIMPs are ruled out.