Halo-dependent Anharmonic Effects in Collective Excitation for Light Dark Matter Direct Detection

TL;DR

This paper studies how anharmonic effects in silicon crystals influence dark matter detection sensitivity, especially considering dark matter substructures suggested by Gaia data, revealing potential sensitivity variations by factors of 2-3.

Contribution

It introduces a model accounting for halo-dependent anharmonic effects in phonon-based dark matter detection, incorporating recent Gaia data on dark matter substructures.

Findings

Anharmonic effects significantly impact detection cross sections.

Dark matter substructures can alter sensitivity by a factor of 2-3.

Likelihood analysis with Gaia data enhances understanding of detection prospects.

Abstract

Phonon, the collective excitation of lattice vibration in the crystal, has been put forward as a means to search for light dark matter. However, the accurate modeling of the multi-phonon production process is challenging in theory. The anharmonicity of the crystal must be taken into account, as it has a significant impact on dark matter-nucleus scattering cross section in the low dark matter mass region. Notably, such an effect is sensitive to the velocity distribution of the dark matter halo. In this work, we consider the potential dark matter substructures indicated by the recent Gaia satellite observation and investigate their impact on the anharmonicity of the silicon crystal. By employing the likelihood analysis with the Asimov dataset, we present the expected sensitivity of dark matter-nucleus interactions, which can differ from the standard halo model by a factor of 2-3.