Limits on Momentum-Dependent Asymmetric Dark Matter with CRESST-II

The usual assumption in direct dark matter searches is to consider only the spin-dependent or spin-independent scattering of dark matter particles. However, especially in models with light dark matter particles $O(\mathrm{GeV}/c^2)$, operators which carry additional powers of the momentum transfer $q^2$ can become dominant. One such model based on asymmetric dark matter has been invoked to overcome discrepancies in helioseismology and an indication was found for a particle with a preferred mass of $3\mathrm{GeV}/c^2$ and a cross section of ${10}^{-37}{\mathrm{cm}}^2$. Recent data from the CRESST-II experiment, which uses cryogenic detectors based on ${\mathrm{CaWO}}_4$ to search for nuclear recoils induced by dark matter particles, are used to constrain these momentum-dependent models. The low energy threshold of 307 eV for nuclear recoils of the detector used, allows us to rule out the proposed best fit value above.

Figure 1

Energy dependent signal survival probability after successive application of the different selection criteria. Figure adapted from [6].

Figure 2

Data plotted in light yield-energy plane. The upper and lower 90% contours of the $e^{-}/\gamma$, oxygen, and tungsten bands are shown in blue, red, and green, respectively. The dashed red line indicates the center of the oxygen band which is used as an upper boundary for the acceptance region which is shaded in yellow. All events in the acceptance region are highlighted in red. Figure adapted from [6].

Figure 3

Recoil spectra for $3\mathrm{GeV}/c^2$ dark matter particles scattering off ${\mathrm{CaWO}}_4$. In dashed black the default spin-independent spectrum is shown, in solid red and dotted blue the effect of the different powers of $q$ on the shape of the recoil spectrum can be seen. All spectra are normalized to one, note, however, that especially for small masses the absolute count rate of the modified spectra may be suppressed by several orders of magnitude.

Figure 4

90% C.L. upper limits on ${\sigma }_0$ for different powers of $q$. The limit for $q^2$-dependent scattering is drawn in solid red, ruling out the best fit point from [3] (magenta cross). For comparison also the limit for $q^4$-dependent scattering (dotted blue) and scalar interaction (dashed black) are shown.