The Standard Model of particle physics is currently regarded as the most comprehensive model for describing the universe. It explains accurately the basic building blocks of matter, which constitute both our surroundings and ourselves, as well as the fundamental forces acting between these particles. However, despite its precision, the model cannot explain all phenomena in the universe. For example, astronomical observations indicate that visible matter is insufficient to fully account for the rotation of galaxies. There must be an as yet unknown form of matter — so-called dark matter — that constitutes a significant portion of the total mass of the universe.
Among the proposed extensions to the Standard Model is a hypothetical fifth force that acts between the elementary particles electrons and neutrons. As it has not yet been proven, this fifth force must be extremely weak. Researchers are trying to track it down with ever more precise measurements. Now an international collaboration of research groups from Germany, Switzerland and Australia has set new upper limits for its strength. They conducted highly precise measurements on calcium isotopes, which they trapped in an ion trap.
Several experimental and theoretical groups from QuantumFrontiers and DQ-mat were involved in the collaboration. The team led by Piet Schmidt, under the direction of Alexander Wilzewski, conducted isotope shift spectroscopy for Ca14+. Andrey Surzhykov’s team performed atomic and nuclear structure calculations for the systems involved, while Elina Fuchs and her team derived the limits of the fifth force.
The joint publication in the current issue of Physical Review Letters is a particularly good example of the outstanding cooperation between the scientists of QuantumFrontiers across different work groups within the cluster of excellence, as well as other partners in the international network.
Physics-Highlight: Searching for a New Force
Original Publication
Wilzewski A, Huber L, Door M, Richter J, Mariotti A et al.
Nonlinear Calcium King Plot Constrains New Bosons and Nuclear Properties.
Physical Review Letters, 134, 233002.
DOI: https://doi.org/10.1103/PhysRevLett.134.233002
