Nature of dark matter and its interactions with the Standard Model

Determine the fundamental nature of dark matter and characterize its interactions with Standard Model fields, including the strong (QCD) sector, to resolve this outstanding problem in contemporary physics.

Background

The paper proposes a precision-spectroscopy approach using a molecular ion (I2+) correlated with an optical atomic clock (Ca+) to search for ultralight dark matter (ULDM) that couples to the QCD sector. This strategy exploits differential sensitivity of molecular vibrational transitions to hadronic parameters compared to electronic atomic transitions.

The authors frame their paper within the broader context that the identity of dark matter and its coupling to Standard Model sectors remain unknown, motivating laboratory searches capable of detecting small oscillations of nuclear parameters induced by ULDM.