Constraints on leptophilic light dark matter from internal heat flux of Earth

TL;DR

This paper investigates how leptophilic light dark matter particles captured by Earth could contribute to its internal heat flux, providing new constraints on their properties by comparing with Earth's measured heat flux of 44 TW.

Contribution

It introduces a novel method to constrain leptophilic light dark matter using Earth's internal heat flux, especially effective for low-mass dark matter.

Findings

Constraints on DM-electron scattering cross section are stronger than direct detection for masses below 0.01 GeV.

Dark matter annihilation/decay inside Earth can significantly contribute to Earth's heat flux.

The steady-state assumption links dark matter capture and annihilation rates to Earth's observed heat flux.

Abstract

Dark Matter in Earth intersecting orbits can scatter off the electrons and lose energy, and finally be gravitationally bound to Earth. Eventually they lose enough energy and accumulate at the core. It is assumed that DM annihilates/decays predominantly into Standard Model particles inside Earth. The heat flux from these processes is compared with the experimentally measured value of internal heat flux of Earth which is 44 TW. Assuming steady state between capture and annihilation/decay, we put constraints on the scattering cross section of DM with electrons as a function of their mass. For low mass regions ($<10^{-2}$GeV), these constraints on leptophilic DM are better than ones obtained from direct-detection experiments.