Anapole Dark Matter after DAMA/LIBRA-phase2

Abstract

We re-examine the case of anapole dark matter as an explanation for the DAMA annual modulation in light of the DAMA/LIBRA-phase2 results and improved upper limits from other DM searches. If the WIMP velocity distribution is assumed to be a Maxwellian, anapole dark matter is unable to provide an explanation of the DAMA modulation compatible with the other searches. Nevertheless, anapole dark matter provides a better fit to the DAMA-phase2 modulation data than an isoscalar spin-independent interaction, due to its magnetic coupling with sodium targets. A halo-independent analysis shows that explaining the DAMA modulation above 2 keVee in terms of anapole dark matter is basically impossible in face of the other null results, while the DAMA/LIBRA-phase2 modulation measurements below 2 keVee are marginally allowed. We conclude that in light of current measurements, anapole dark matter does not seem to be a viable explanation for the totality of the DAMA modulation.

Comments: 16 pages, 6 figures. Updated to published version