Search for axion-like dark matter through nuclear spin precession in electric and magnetic fields (1708.06367v1)

Abstract: We report on a search for ultra-low-mass axion-like dark matter by analysing the ratio of the spin-precession frequencies of stored ultracold neutrons and $^{199}$Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range $10^{-24}~\textrm{eV} \le m_a \le 10^{-17}~\textrm{eV}$. Our null result sets the first laboratory constraints on the coupling of axion dark matter to gluons, which improve on astrophysical limits by up to 3 orders of magnitude, and also improves on previous laboratory constraints on the axion coupling to nucleons by up to a factor of 40.

• The paper improved laboratory axion-gluon coupling limits by three orders of magnitude over previous astrophysical constraints.
• The paper employed nuclear spin precession measurements of ultracold neutrons and Hg atoms in electric and magnetic fields to detect axion-induced oscillations.
• The paper established robust exclusion limits on axion-nucleon couplings, refining theoretical models and guiding future dark matter research.

Search for Axion-like Dark Matter through Nuclear Spin Precession

The paper presents an investigation into the interactions between axion-like dark matter and gluons and nucleons. The analysis focuses on detecting the effects of axion-induced oscillations, with implications for understanding fundamental particle interactions and the nature of dark matter. Authors employed sophisticated methods to search for signals of ultra-low-mass axion-like dark matter, leveraging the dynamics of nuclear spin precession in electric and magnetic fields.

Experimental Methodology and Analysis

The investigation aimed to identify axion interactions by analyzing the spin-precession frequency ratios of ultracold neutrons and $^{199}$Hg atoms stored in controlled electromagnetic environments. The absence of a signal from axion-like dark matter within the axion mass range of $10^{-24}~\textrm{eV}$ to $10^{-17}~\textrm{eV}$ established laboratory constraints on axion couplings which supersede previous astrophysical limits. The experiment was twofold: initially utilizing data from the Sussex--RAL--ILL nEDM experiment at ILL between 1998 to 2002, followed by extended analysis using data from the PSI nEDM experiment between 2015 and 2016.

Key Results and Numerical Constraints

The null findings of axion-like dark matter effects provided significant numerical constraints:

• An improvement on axion-gluon coupling limits by 3 orders of magnitude over astrophysical constraints.
• Enhanced laboratory constraints on axion-nucleon coupling by factors reaching up to 40.

This advancement establishes robust exclusion limits for axion interactions, constraining super-Planckian axion decay constants and coupling strengths intrinsically weaker than gravitational forces.

Implications and Potential Developments

The lack of observed oscillations does not diminish the importance of this research. Instead, these limits refine theoretical models and guide future investigations into weakly interacting sub-eV dark matter candidates. The results imply stringent boundaries on axion particle models, particularly those derived from string theory such as axion-like particles. Future experiments could exploit advanced nuclear spin-precession techniques and enhanced detection sensitivity to explore longer oscillation periods and finer mass resolutions, potentially revealing new physics in dark matter interactions.

Conclusion

This research constitutes an essential contribution to experimental attempts at understanding dark matter particle interactions within quantum chromodynamics frameworks. By establishing stringent laboratories constraints, the work challenges future theoretical models and paves the way for further investigation of axion-like particles in the sub-eV mass range. The implications stretch beyond dark matter characterization to influence theories around fundamental particle interactions.