The shadow of dark matter as a shadow of string theory

TL;DR

This paper proposes that string theory can explain electroweak dipole moments in dark matter through a Kalb-Ramond coupling, linking string interactions to dark matter detection prospects and fundamental physics.

Contribution

It introduces a novel mechanism connecting string theory to dark matter via a U_Y(1) portal and predicts testable electron recoil signals in direct detection experiments.

Findings

Recoil cross sections are below current experimental limits.

The U_Y(1) portal can be tested with larger detectors.

Electroweak dipole dark matter offers a window into string phenomenology.

Abstract

We point out that string theory can solve the conundrum to explain the emergence of an electroweak dipole moment from electroweak singlets through induction of those dipole moments through a Kalb-Ramond dipole coupling. This can generate a U_Y(1) portal to dark matter and entails the possibility that the U_Y(1) gauge field is related to a fundamental vector field for open string interactions. The requirement to explain the observed dark matter abundance relates the coupling scale in the corresponding low-energy effective U_Y(1) portal to the dark matter mass. The corresponding electron recoil cross sections for a single dipole coupled dark matter species are generically below the current limits from XENON, SuperCDMS and SENSEI, except in the GeV mass range if the electric dipole coupling becomes stronger than the magnetic coupling. Furthermore, the recoil cross sections are above the neutrino floor and the U_Y(1) portal can be tested with longer exposure or larger detectors. Discovery of electroweak dipole dark matter would therefore open an interesting window into string phenomenology.