Perez Lab

Dilatons are pseudo-Nambu-Goldstone bosons arising from the breaking of conformal invariance. In this letter we point out that in general a dilaton mass has a power-law dependence on a small parameter related to the explicit breaking of conformal invariance whereas the ratio between the ultraviolet and infrared scales in the theory is exponentially related to the same parameter. We show that this scaling results in a separation between the dilaton mass and the infrared scale that can not be arbitrary large. Therefore a small dilaton mass necessarily is associated to a secluded conformal sector. We argue that the fact that the dilaton field must have a small displacement from the minimum of its effective potential generated near the infrared scale precludes a cosmologically interesting amount of dilatonic dark matter to be produced by a misalignment mechanism in the early Universe.

The nature of dark matter (DM) and its interaction with the Standard Model (SM) is one of the biggest open questions in physics nowadays. The vast majority of theoretically-motivated Ultralight-DM (ULDM) models predict that ULDM couples dominantly to the SM strong/nuclear sector. This coupling leads to oscillations of nuclear parameters that are detectable by comparing clocks with different sensitivities to these nature's constants. Vibrational transitions of molecular clocks are more sensitive to a change in the nuclear parameters than the electronic transitions of atomic clocks. Here, we propose the iodine molecular ion, I⁺₂ , as a sensitive detector for such a class of ULDM models. The iodine's dense spectrum allows us to match its transition frequency to that of an optical atomic clock (Ca⁺) and perform correlation spectroscopy between the two clock species. With this technique, we project a few-orders-of-magnitude improvement over the most sensitive clock comparisons performed to date. We also briefly consider the robustness of the corresponding "Earth-bound" under modifications of the Z_N-QCD axion model.

Axion-gluon interaction induces quadratic couplings between the axion and the matter fields. We find that, if the axion is an ultralight dark matter field, it induces small oscillations of the mass of the hadrons as well as other nuclear quantities. As a result, atomic energy levels oscillate. We use currently available atomic spectroscopy data to constrain such axion-gluon coupling. We also project the sensitivities of future experiments, such as ones using molecular and nuclear clock transitions. We show that current and near-future experiments constrain a finely tuned parameter space of axion models. These can compete with or dominate the already-existing constraints from oscillating neutron electric dipole moment and supernova bound, in addition to those expected from near future magnetometer-based experiments. We also briefly discuss the reach of accelerometers and interferometers.