Constraints on Long-Ranged Interactions Between Dark Matter and the Standard Model

TL;DR

This paper investigates potential weak, long-range forces between dark matter and the Standard Model, deriving constraints from particle interactions and astrophysical observations, notably the dynamics of ultrafaint dwarf galaxies.

Contribution

It introduces novel constraints on long-range dark matter interactions by combining particle physics limits with astrophysical effects observed in dwarf galaxies.

Findings

Long-range forces would induce detectable interactions among Standard Model particles.

Such forces could alter stellar orbits in dwarf galaxies, providing observational constraints.

The study sets the strongest limits to date on these hypothetical interactions.

Abstract

Dark matter's existence is known thanks to its gravitational interaction with Standard Model particles, but it remains unknown whether this is the only force present between them. While many searches for such new interactions with dark matter focus on short-range, contact-like interactions, it is also possible that there exist weak, long-ranged forces between dark matter and the Standard Model. In this work, we present two types of constraints on such new interactions. First, we consider constraints arising from the fact that such a force would also induce long range interactions between Standard Model particles themselves, as well as between dark matter particles themselves. Combining the constraints on these individual forces generally sets the strongest constraints available on new Standard Model-dark matter interactions. Second, we consider the possibility of constraining new long-ranged interactions between dark matter and the Standard Model using the effects of dynamical friction in ultrafaint dwarf galaxies, especially Segue I. Such new interactions would accelerate the transfer of kinetic energy from stars to their surrounding dark matter, slowly reducing their orbits; the present-day stellar half-light radius of Segue I therefore allows us to exclude new forces which would have reduced stars' orbital radii below this scale by now.