Is matter the antimatter of dark matter

13.11.2019 19:33

New approach to the search for dark matter

Petra Giegerich Communication and press
Johannes Gutenberg University Mainz

Researchers want to use antimatter to track down dark matter.

Scientists from the BASE collaboration at the European research center CERN together with a working group at the PRISMA + cluster of excellence at Johannes Gutenberg University Mainz (JGU) have taken a completely new approach to the search for dark matter: For the first time, they have examined the influence of dark matter on antimatter instead of on investigates ordinary matter. The results of their work are published in the latest issue of the renowned journal "Nature". Scientists from the Japanese research center RIKEN, the Max Planck Institute for Nuclear Physics in Heidelberg (MPIK) and the Physikalisch-Technische Bundesanstalt (PTB) Braunschweig, who in turn are part of the Max Planck-RIKEN-PTB Center for Time, Constants and Fundamental, are involved Symmetries, as well as CERN, Johannes Gutenberg University Mainz (JGU), Helmholtz Institute Mainz (HIM), University of Tokyo, GSI Darmstadt and Leibniz University Hannover.

"So far, scientists have always used matter-based samples in precision experiments at low energies in order to demonstrate a coupling of dark matter on them," explains the first author of the current study, Dr. Christian Smorra, who is currently working at the Japanese research institute RIKEN and who will set up a working group at the Institute for Physics at JGU over the next few years as part of an ERC Starting Grant. “For the first time we are explicitly looking for an interaction between dark matter and antimatter. Most studies assume a symmetrical interaction of dark matter with particles and antiparticles. In our study, we check whether this is really the case. "

This approach has a double charm: So far, very little is known about the microscopic properties of dark matter - one of the much discussed candidates are so-called ALPs (Axion Like Particles). Furthermore, the Standard Model of Particle Physics does not explain why there is so much more matter than antimatter in the universe. "We hope to find a clue through our experiments that could connect the two questions," said Dr. Yevgeny Stadnik, who participated in the study as part of a Humboldt Fellowship at HIM. “Because neither theoretically nor experimentally, an asymmetric interaction of this kind has not been investigated before. In our current research we are taking a first step in this direction. "

Trapped antiprotons are said to provide clues to dark matter
The scientist's object of investigation is a single antiproton, trapped in a special particle trap, a so-called Penning trap. The scientists generated these particles at the Antiproton Decelerator (AD) at CERN, the world's only research facility in which antiprotons are made available at low energy. The scientists then stored and examined the antiprotons generated there in the trap system of the BASE collaboration.

The antiproton not only has a charge, but also its own angular momentum - in technical jargon, spin. In a magnetic field, this spin precesses with a very specific, constant frequency - the spin precession frequency. “We could detect the presence of dark matter by changing this frequency,” says Christian Smorra. “We consider the potential particles of dark matter as a classic field with a certain wavelength. The dark matter waves run continuously through our experiment and periodically change the actually constant precession frequency of the antiproton spin in the magnetic field. "

With their experimental setup, the researchers searched a certain frequency range - and so far have not found any evidence of dark matter. "With our current measurement setup we did not find any significant and periodic change in the spin precession frequency of the antiproton," explains Stefan Ulmer, spokesman for the BASE collaboration at CERN. “Nevertheless, compared to astrophysical observations, we have exceeded the sensitivity by up to five orders of magnitude. This means that, based on the current sensitivity of our experiment, we have defined a new upper limit for the strength of a potential interaction between dark matter and antimatter. "

Two research groups merged
Basically, the scientists have brought together two research groups in their current project. The BASE collaboration at CERN has long and successfully dealt with the fundamental properties of the antiproton, while the group around Prof. Dr. Dmitry Budker, scientist at JGU's PRISMA + Cluster of Excellence and at HIM, is very active in the search for dark matter and made a decisive contribution to the interpretation of the study. "We noticed that our research shows a lot of overlap and that is where the idea for this new approach to the search for dark matter was born," says Dmitry Budker.

In the future, the scientists want to further improve the accuracy of the measurement of the spin precession frequency of the antiproton - this would then also be the prerequisite for making the antimatter-based search for dark matter even more sensitive. For this purpose, in the working group of Prof. Dr. Jochen Walz at the Institute for Physics at JGU, in collaboration with MPIK and RIKEN, is developing new cooling methods for protons and antiprotons, while a group of scientists at PTB Braunschweig, Leibniz Universität Hannover and RIKEN are currently using methods for quantum logic spectroscopy of the antiproton spin developed. It would also be interesting to carry out similar studies with other antiparticles, such as positrons or antimuons.

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Stefan Ulmer working on the BASE experiment on the Antiproton Decelerator (AD).
Photo / ©: Maximilien Brice / CERN
Penning trap system of the BASE collaboration
Photo / ©: Stefan Sellner, Fundamental Symmetries Laboratory, RIKEN, Japan

Scientific contact:

Dr. Christian Smorra
Quantum, atomic and neutron physics (QUANTUM)
Institute for Physics
Johannes Gutenberg University Mainz
55099 Mainz
Tel .: 06131 39-25953
Email: [email protected]

Dr. Stefan Ulmer
BASE collaboration speaker
1211 Geneva
Tel .: 0041 75411-9072
Email: [email protected]

Original publication:

C. Smorra, YV Stadnik, PE Blessing, M. Bohman, MJ Borchert, JA Devlin, S. Erlewein, JA Harrington, T. Higuchi, A. Mooser, G. Schneider, M. Wiesinger, E. Wursten, K. Blaum , Y. Matsuda, C. Ospelkaus, W. Quint, J. Walz, Y. Yamazaki, D. Budker & S. Ulmer, "Direct limits on the interaction of antiprotons with axion-like dark matter"
DOI: 10.1038 / s41586-019-1727-9

Additional Information: - BASE: Baryon Antibaryon Symmetry Experiment at CERN - Institute for Physics at JGU

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