Interfering Composite Asymmetric Dark Matter for DAMA and CoGeNT

TL;DR

The paper tackles the tension between DAMA/CoGeNT signals and null results from other direct-detection experiments by proposing a light composite asymmetric DM model in which Higgs- and photon-exchange in WIMP-nucleus scattering interfere. This interference can yield a neutron-to-proton coupling ratio around $f_n/f_p \simeq -0.71$, producing overlapping DAMA/CoGeNT regions for $M_\phi \approx 8$ GeV and $\sigma_p \approx 2\times 10^{-38}$ cm$^2$ while evading CDMS/Xenon bounds; the required compositeness scale is $\Lambda \sim v_{EW}$ with couplings $d_B$, $d_H$ of order unity to ten. A concrete UV completion is provided in Ultra Minimal Technicolor (UMT), where a light complex scalar $\phi$ arises from the electroweak-scale strong dynamics and couples to the Higgs through higher-dimension operators, reproducing the needed interference pattern. Electroweak sphalerons set the relic-density relation $\Omega_{DM}/\Omega_B \sim 5$ and favor $M_\phi \sim 8$ GeV, while sufficient annihilation eliminates any symmetric component, yielding a scenario with potentially observable collider phenomenology and a natural link between baryogenesis and dark matter.

Abstract

We provide a simple mechanism for reconciling the direct dark matter experimental results. We consider light asymmetric composite dark matter which scatters off nuclei via Higgs and photon exchange. We demonstrate that the interference between these two channels naturally accommodates the experimental results. We discover that this happens for a compositeness scale of the order of the electroweak. We also provide a model realization based on strong dynamics at the electroweak scale.

Figures (1)

• Figure 1: Favored regions and exclusion contours in the $(M_\phi, \sigma_p)$ plane for the standard case $f_n / f_p = 1$ (top panel) and the case $f_n / f_p = - 0.71$ (bottom panel). The green contour is the $3 \sigma$ favored region by DAMA/LIBRA Savage:2010tg assuming no channeling Bozorgnia:2010xy and that the signal arises entirely from Na scattering; the blue region is the $90 \%$ CL favored region by CoGeNT; the dashed line is the exclusion plot by CDMS II Soudan Ahmed:2010wy; and the black and blue lines are respectively the exclusion plots from the Xenon10 Angle:2011th and Xenon100 Aprile:2011hi experiments. The common region passing all the constraints is shown in red.