title: On the existence of low-mass dark matter and its direct detection.
abstract: Dark Matter (DM) is an elusive form of matter which has been postulated to explain astronomical observations through its gravitational effects on stars and galaxies, gravitational lensing of light around these, and through its imprint on the Cosmic Microwave Background (CMB). This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics. Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far. While its large interaction strength might at first seem unlikely, neither constraints from particle physics nor cosmological/astronomical observations are sufficient to rule out this type of DM, and it motivates our proposal for direct detection by optomechanics technology which should soon be within reach, namely, through the precise position measurement of a levitated mesoscopic particle which will be perturbed by elastic collisions with χ particles. We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too.
authors.affiliation: Quantum, Light and Matter, Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Bateman
authors.affiliation: Astronomy, Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom.
authors.forename: Ian
authors.initials: I
authors.lastname: McHardy
authors.affiliation: 1] High Energy Physics Theory, Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom [2] Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Merle
authors.affiliation: High Energy Physics Theory, Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom.
authors.forename: Tim R
authors.initials: TR
authors.lastname: Morris
authors.affiliation: Quantum, Light and Matter, Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Ulbricht