The Mystery of Matter: Jülich Researchers Develop New Method to Search for Unknown Physics
16 June 2026
Why do we exist at all? Researchers in Jülich have investigated a new clue: the electric dipole moment of the deuteron. The effect remains invisible—but that is precisely what sets important constraints and brings physics one step closer to understanding our universe.
This question has occupied scientists for decades. According to current understanding, the universe as we know it should never have come into existence. In the first moments after the Big Bang, there was a near-perfect balance between matter and antimatter. When the two meet, they annihilate each other completely. So, strictly speaking, nothing should have remained—yet our world consists almost entirely of matter.
“The very fact that matter exists today initially contradicts our physical expectations,” explains Jörg Pretz, Deputy Director of the Institute for Nuclear Physics (IKP) at Forschungszentrum Jülich.
There must therefore have been processes in the early universe that created a slight excess of matter over antimatter. Physics already knows of some such mechanisms, but they are insufficient to explain the observed dominance of matter.
Since the early universe cannot be observed directly, researchers search for indirect clues in the properties of elementary particles. One possible signature is the electric dipole moment—a minute separation of positive and negative charge within a particle.
“The Standard Model of particle physics does predict such effects, but only at vanishingly small levels,” explains Volker Hejny from the IKP. “Any effect measurable with today’s methods would therefore point to new physics.”
The search for electric dipole moments has a long tradition. Since the 1950s, researchers have investigated particles such as neutrons—so far without success.
Now, the international JEDI Collaboration at Forschungszentrum Jülich has achieved another important milestone: for the first time, researchers searched for the electric dipole moment of the deuteron, a bound state consisting of a proton and a neutron. To do so, they used a storage ring—a special type of particle accelerator.
The COSY storage ring in Jülich was one of only a few accelerator facilities worldwide capable of providing spin-polarized particle beams, a crucial prerequisite for this measurement. The results have now been published in the prestigious journal Physical Review Letters.
The result: no electric dipole moment could be detected; the measured value is consistent with zero.
“The possible displacement between the centers of positive and negative charge is smaller than one ten-thousandth of the deuteron’s diameter,” says Achim Andres, a doctoral researcher in Jörg Pretz’s group and first author of the study. “If the deuteron were the size of a stadium, the displacement would be at most on the order of a few millimeters.”
Although the measurement precision cannot yet compete with that of other experiments, the study demonstrates one thing above all: storage rings are exceptionally well suited for the search for electric dipole moments. “For the deuteron, a storage ring is the best available measurement method,” emphasizes Pretz.
Building on these findings, new storage rings specifically designed for such precision measurements are already being planned. They are expected to improve the sensitivity of the method by many orders of magnitude, thereby increasing the chances of revealing traces of new physics.
One bittersweet note remains: the COSY storage ring was shut down in 2023 after more than 30 years of operation. Nevertheless, the insights gained will shape future experiments in the search for an answer to one of the greatest questions in physics.
Original publication: First experimental limit on the permanent electric dipole moment of the deuteron, A. Andres et al., Phys. Rev. Lett., 2026, DOI: 10.1103/ns3s-ld4k
