Constraints on dark matter protohalos in effective theories and neutrinophilic dark matter

Ian M Shoemaker

doi:10.1016/j.dark.2013.07.002

Abstract

Abstract The mass of primordial dark matter (DM) protohalos remains unknown. However, the missing satellites problem may be an indication that they are quite large. In this paper, we use effective field theory to map constraints on dark matter-SM interactions into limits on the mass of DM protohalos. Given that leptons remain in the thermal bath until late times, we focus on their interactions with DM. To illustrate the method, we use the null results of LEP missing energy searches along with Fermi-LAT searches for DM annihilation in nearby dwarf galaxies, to derive limits on the protohalo mass, ≲ (10−6 to 10−1) M⊙, with the range depending on the DM mass and the operator. Thus, if DM is to remain thermally coupled until late times and account for the missing satellites, charged lepton interactions are insufficient. This motivates neutrinophilic DM, which can have protohalo masses orders of magnitude larger, with constraints arising from Planck, IceCube and unpublished Super-K data. We show that effective neutrinophilic models offer a viable solution to the missing satellites problem for sub-GeV DM masses with larger than WIMP-sized annihilation cross sections.

Highlights

One of the simplest particle candidates for dark matter (DM) is the thermally produced weakly-interacting massive particle (WIMP) [1]
With Planck, IceCube, Super-K being the only relevant experimental probes, we find that for νDM to accommodate the missing satellite problem thermal DM must be sub-GeV in mass and with a larger than WIMP-sized annihilation cross section
Given that the charged leptons and neutrinos are among the last SM particles remaining in the thermal bath, we will be interested in the coupling of DM to these particles

Summary

INTRODUCTION

One of the simplest particle candidates for DM is the thermally produced weakly-interacting massive particle (WIMP) [1]. To remain as model-independent as possible we assume that lepton-DM interactions can be described using effective field theory This is an excellent approximation at the low temperatures relevant for kinetic decoupling, though it becomes circumspect at high-energy colliders. With Planck, IceCube, Super-K being the only relevant experimental probes, we find that for νDM to accommodate the missing satellite problem thermal DM must be sub-GeV in mass and with a larger than WIMP-sized annihilation cross section. Such a scenario can obtain the correct thermal relic abundance if dark matter carries a nonzero asymmetry [2]. VI we conclude with a discussion of possible extensions and future probes of νDM

EFFECTIVE DARK MATTER-LEPTON INTERACTIONS

CONSTRAINING DM INTERACTIONS

KINETIC DECOUPLING AND DARK MATTER PROTOHALOS

Charged Lepton Constraints

Neutrinophillic DM

DISCUSSION AND CONCLUSIONS