Dark Moments and the DAMA-CoGeNT Puzzle

TL;DR

This paper investigates the DAMA-CoGeNT puzzle by incorporating velocity-dependent dark-m matter–nucleus scattering and a realistic treatment of experimental uncertainties. It shows that standard spin-independent scattering struggles to reconcile the signals and null results, whereas non-standard operators—most notably the magnetic-dipole interaction—yield significantly improved global consistency, provided the astrophysical and detector parameters are favorably chosen. The authors connect these operators to concrete models with a light dark photon via kinetic mixing, demonstrating that large cross-sections can arise without conflicting with null experiments. The work emphasizes systematic error quantification, highlighting that, in the low-mass DM regime, uncertainties must be rigorously accounted for before ruling out viable scenarios.

Abstract

We consider the velocity dependence arising from scattering through dark multipole moments, and its effects on the consistency of the signals observed by DAMA and CoGeNT with the dark matter hypothesis. We focus on the effects of the experimental uncertainties on the fits, and show that the two experiments combined favor dark matter scattering with a velocity-dependent cross-section over standard velocity and spin-independent scattering. When appropriate uncertainties are taken into account, we show that agreement of the two signals with each other and with the results of null experiments can be obtained.

Figures (7)

• Figure 1: left panel: Allowed regions (90 and 99% C.L., corresponding to purple and blue) for standard spin-independent scattering, $Q_{Na} = 0.3$, $Q_{Ge}$ from Eq. (\ref{['GeQ1']}). DAMA regions are shown in a darker color than the CoGeNT regions. A green band shows 90% exclusion regions from XENON10 depending on the extrapolation of ${\cal L}_{\rm eff}$ below threshold (central values of Manzur are taken and extrapolated to remain constant (light dashed) below threshold, or to drop linearly to zero (dark dashed); these extrapolations correspond roughly to Case 1 and Case 2 of sorensen). CDMS-Si (red dot-dashed) and SIMPLE (short dashed) constraints are also shown. right panel: Same as left panel, but with $Q_{Na} = 0.45$ and $Q_{Ge}$ from Eq. (\ref{['GeQ2']}).
• Figure 2: left panel: Allowed regions (90 and 99% C.L., corresponding to purple and blue) for standard spin-independent scattering, $Q_{Na} = 0.45$, $Q_{Ge}$ from Eq. (\ref{['GeQ2']}) with $A_Q = 0.85$. DAMA regions are shown in a darker color than the CoGeNT regions. A green band shows 90% exclusion regions from XENON10 depending on the extrapolation of ${\cal L}_{\rm eff}$ below threshold (central values of Manzur are taken and extrapolated to remain constant (light dashed) below threshold, or to drop linearly to zero (dark dashed)). CDMS-Si (red dot-dashed) and SIMPLE (short dashed) constraints are also shown. right panel: Same as left panel, but with form factor from Eq. (\ref{['r02']}) and 20% threshold uncertainty in CDMS-Si taken into account.
• Figure 3: left panel: Allowed regions (90 and 99% C.L.) for scattering through the anapole operator, $Q_{Na} = 0.3$, $Q_{Ge}$ from Eq. (\ref{['GeQ1']}) with $A_Q=1$, and form factor from Eq. (\ref{['r01']}). DAMA regions are shown in a darker color than the CoGeNT regions. A green band shows 90% exclusion regions from XENON10 depending on the extrapolation of ${\cal L}_{\rm eff}$ below threshold (central values of Manzur are taken and extrapolated to remain constant (light dashed) below threshold, or to drop linearly to zero (dark dashed)). CDMS-Si (red dot-dashed) and SIMPLE (short dashed) constraints are also shown. right panel: Same as left panel, but with $Q_{Na} = 0.45$ and 20% threshold uncertainty in CDMS-Si taken into account.
• Figure 4: left panel: Allowed regions (90 and 99% C.L.) for scattering through the magnetic dipole operator, $Q_{Na} = 0.3$, $Q_{Ge}$ from Eq. (\ref{['GeQ1']}) with $A_Q=1$, and form factor from Eq. (\ref{['r01']}). DAMA regions are shown in a darker color than the CoGeNT regions. A green band shows 90% exclusion regions from XENON10 depending on the extrapolation of ${\cal L}_{\rm eff}$ below threshold (central values of Manzur are taken and extrapolated to remain constant (light dashed) below threshold, or to drop linearly to zero (dark dashed)). CDMS-Si (red dot-dashed) and SIMPLE (short dashed) constraints are also shown. right panel: Same as left panel, but with $Q_{Na} = 0.45$ and 20% threshold uncertainty in CDMS-Si taken into account.
• Figure 5: left panel: Same as Fig. (\ref{['fig:standard2']})b (standard WIMP coupling), but with $v_0 = 270 \hbox{km/s}$. right panel: Same as Fig. (\ref{['fig:anapole1']})b (scattering through anapole operator), but with $v_0 = 270 \hbox{km/s}$.