The Migdal effect inside detectors provides a new possibility of probing the sub-GeV dark matter (DM) particles. While there has been well-established methods treating the Migdal effect in isolated atoms, a coherent and complete description of the valence electrons in semiconductor is still absent. The bremstrahlung-like approach is a promising attempt, but it turns invalid for DM masses below a few tens of MeV. In this paper, we lay out a framework where phonon is chosen as an effective degree of freedom to describe the Migdal effect in semiconductors. In this picture, a valence electron is excited to the conduction state via exchange of a virtual phonon, accompanied by a multi-phonon process triggered by an incident DM particle. Under the incoherent approximation, it turns out that this approach can effectively push the sensitivities of the semiconductor targets further down to the MeV DM mass region.
@article{arxiv.2205.03395,
title = {Phonon-mediated Migdal effect in semiconductor detectors},
author = {Zheng-Liang Liang and Chongjie Mo and Fawei Zheng and Ping Zhang},
journal= {arXiv preprint arXiv:2205.03395},
year = {2022}
}
Comments
In the previous version, the $T_{0}$ term is omitted in the numerical implementation of Eq.(3.4). In this version, the $T_{0}$ term is included, and it is found that the Migdal event rates calculated from the phonon-mediated approach and the impulse approximation coincide quite well even in the low DM mass range