Direct limits on the interaction of antiprotons with axion-like dark matter

• Published in: Nature (London) Vol. 575; no. 7782; pp. 310 - 314
• Main Authors: Smorra, C, Stadnik, Y V, Blessing, P E, Bohman, M, Borchert, M J, Devlin, J A, Erlewein, S, Harrington, J A, Higuchi, T, Mooser, A, Schneider, G, Wiesinger, M, Wursten, E, Blaum, K, Matsuda, Y, Ospelkaus, C, Quint, W, Walz, J, Yamazaki, Y, Budker, D, Ulmer, S
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.11.2019
• Subjects: Analysis; Antimatter; Antiparticles; Antiprotons; Asymmetry; Baryons; Bosons; Control; Coupling; Dark matter; Dark matter (Astronomy); Experiments; Flux density; Interaction parameters; Matter & antimatter; Nuclear reactions; Observations; Particle physics; Protons; Standard model (particle physics); Symmetry; Universe; Japan
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-019-1727-9

Astrophysical observations indicate that there is roughly five times more dark matter in the Universe than ordinary baryonic matter , and an even larger amount of the Universe's energy content is attributed to dark energy . However, the microscopic properties of these dark components remain unknown. Moreover, even ordinary matter-which accounts for five per cent of the energy density of the Universe-has yet to be understood, given that the standard model of particle physics lacks any consistent explanation for the predominance of matter over antimatter . Here we present a direct search for interactions of antimatter with dark matter and place direct constraints on the interaction of ultralight axion-like particles (dark-matter candidates) with antiprotons. If antiprotons have a stronger coupling to these particles than protons do, such a matter-antimatter asymmetric coupling could provide a link between dark matter and the baryon asymmetry in the Universe. We analyse spin-flip resonance data in the frequency domain acquired with a single antiproton in a Penning trap to search for spin-precession effects from ultralight axions, which have a characteristic frequency governed by the mass of the underlying particle. Our analysis constrains the axion-antiproton interaction parameter to values greater than 0.1 to 0.6 gigaelectronvolts in the mass range from 2 × 10 to 4 × 10 electronvolts, improving the sensitivity by up to five orders of magnitude compared with astrophysical antiproton bounds. In addition, we derive limits on six combinations of previously unconstrained Lorentz- and CPT-violating terms of the non-minimal standard model extension .