Effective Field Theory of Dark Matter Direct Detection With Collective Excitations

Understand

We develop a framework for computing light dark matter direct detection rates through single phonon and magnon excitations via general effective operators.

• Our work generalizes previous calculations focused on spin-independent interactions involving the total nucleon and electron numbers $N$ (the usual route to excite phonons) and spin-dependent interactions involving the total electron spin $S$ (the usual route to excite magnons), leading us to identify new responses involving the orbital angular momenta $L$, as well as spin-orbit couplings $L\otimes S$ in the target.
• All four types of responses can excite phonons, while couplings to electron's $S$ and $L$ can also excite magnons.
• We apply the effective field theory approach to a set of well-motivated relativistic benchmark models, including (pseudo-)scalar mediated interactions, and models where dark matter interacts via a multipole moment, such as a dark electric dipole, magnetic dipole or anapole moment.