Constraints on bosonic dark matter from ultralow-field nuclear magnetic resonance

Abstract

The nature of dark matter, the invisible substance making up over 80% of the matter in the Universe, is one of the most fundamental mysteries of modern physics. Ultralight bosons such as axions, axion-like particles or dark photons could make up most of the dark matter. Couplings between such bosons and nuclear spins may enable their direct detection via nuclear magnetic resonance (NMR) spectroscopy: as nuclear spins move through the galactic dark-matter halo, they couple to dark-matter and behave as if they were in an oscillating magnetic field, generating a dark-matter-driven NMR signal. As part of the Cosmic Axion Spin Precession Experiment (CASPEr), an NMR-based dark-matter search, we use ultralow-field NMR to probe the axion-fermion "wind" coupling and dark-photon couplings to nuclear spins. No dark matter signal was detected above background, establishing new experimental bounds for dark-matter bosons with masses ranging from 1.8 × 10 −16 to 7.8 × 10 −14 eV.

Axion quark nuggets and how a global network can discover them

“…The starting point of our analysis is the Hamiltonian describing the coupling of the spin operator (for electrons or nucleons) with the gradient of the axion field. The same coupling was discussed for the CASPEr experiment [40][41][42] in the case of nucleons and for QUAX [43] in the case of electrons. This coupling is analogous to the Zeeman effect (the basis of magnetometry [44]) with the gradient of the pseudoscalar ∇a(r, t) being a pseudovector analogous to magnetic field:…”

“…Daily modulations are also present in galactic-axion "wind" experiments such as those of Refs [41,42,52]…”

Axion-like relics: new constraints from old comagnetometer data

“…3, the region labeled as 'long-range' represents the merging of two separate bounds from the nonobservation of new long range interactions [40,53]. The 'ν n /ν Hg ' region is excluded from not measuring anomalous fields in a system of mercury atoms and free neutrons [62], and the 'CASPEr (ZULF)' region is excluded by the phase I run of this low-frequency NMR experiment [55]. The bound from the CASPEr ZULF comagnetometer experiment is presented as the 'CASPEr (comag.)'…”

“…region is excluded by the non-observation of the effect of anomalous DM axion fields on 1 H and 13 C [39]. The 'CASPEr (ZULF)' shaded region indicates the phase-I bound of that experiment [55] which looks for anomalous fields by utilizing NMR methods. The 'neutron star' band indicates the constraints from neutron star cooling considerations [56].…”

Extreme nuclear magnetic resonance: Zero field, single spins, dark matter…

“…While analytical applications were the initial motivation for the development of ZULF NMR, it was quickly realized that there is also a potential for fundamental-physics experiments [12,13], including searches for so-called "ultralight bosonic dark matter" that has already produced significant results [14,15] thus far corresponding to exclusion of certain parts of the plausible dark-matter parameter space. Another initially unanticipated application is robust quantum control and implementation of quantum gates in the ZULF regime [16].…”