Continuum-mediated self-interacting dark matter

Ian Chaffey,Philip Tanedo,Sylvain Fichet

doi:10.1007/jhep06(2021)008

Abstract

Dark matter may self-interact through a continuum of low-mass states. This happens if dark matter couples to a strongly-coupled nearly-conformal hidden sector. This type of theory is holographically described by brane-localized dark matter interacting with bulk fields in a slice of 5D anti-de Sitter space. The long-range potential in this scenario depends on a non-integer power of the spatial separation, in contrast to the Yukawa potential generated by the exchange of a single 4D mediator. The resulting self-interaction cross section scales like a non-integer power of velocity. We identify the Born, classical and resonant regimes and investigate them using state-of-the-art numerical methods. We demonstrate the viability of our continuum-mediated framework to address the astrophysical small-scale structure anomalies. Investigating the continuum-mediated Sommerfeld enhancement, we demonstrate that a pattern of resonances can occur depending on the non-integer power. We conclude that continuum mediators introduce novel power-law scalings which open new possibilities for dark matter self-interaction phenomenology.

Highlights

A dark sector is a set of fields that include dark matter and low-mass particles that mediate interactions of the dark matter [1,2,3,4,5,6]
A key result of our study is that continuummediated interactions leads to a non-integer velocity dependence on the dark matter selfscattering cross section, a quantity that relates the fundamental particle physics parameters of the dark sector to astronomical observations
We propose a model where dark matter self-interacts through a continuum of 4D mediators

Summary

Introduction

A dark sector is a set of fields that include dark matter and low-mass particles that mediate interactions of the dark matter [1,2,3,4,5,6] If these mediators interact with the Standard Model, their signatures may appear in a suite of laboratory based experiments. Even if these Standard Model interactions are negligible, the mediators induce long-range potentials between dark matter particles that may be tested astronomically [7, 8]. The dynamics of the model generate a long-range potential on the UV brane that scales as a non-integer power of separation,

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