The Positronium it is an atom composed of an electron and a nucleus formed by a positron, its antiparticle. New research has confused scientists, measurements don’t agree with theoretical predictions, and physicists don’t know why.
There appears to be no error in the calculations or the experiment, according to the researchers. And no new phenomenon, like a new particle, doesn’t seem to provide any new answers.
The positronium is a relatively simple atom, with only two particles and without the complex structure of a larger nucleus, it should be a great test for quantum electrodynamics. The theory, which has Richard Feynman among its main authors, provides the best description of the electromagnetic interactions involving photons and charged particles. The presence of antimatter makes the particle unstable.
A team of researchers from University College London measured la separation between two energy levels, known as fine structure. The researchers formed the atoms of positronium, which is an unstable particle, by firing a beam of positron at a target, where they meet with electrons. Then the atoms were manipulated by a laser to make them reach the appropriate energy level and then hit with microwaves to make them make a further energy leap.
The researchers determined exactly the frequency needed for the jump, which is the equivalent of the energy difference between the two levels. There frequency expected from the calculations is 18.498 megahertz, what the researchers measured is 18.501 megahertz, a difference of 0.002 percent. A small but significant difference.
Scientists immediately looked for problems in the experimental setup that could explain the results, but found nothing. Further experiments will be needed to investigate the origin of this discrepancy.
“If there are any significant discrepancies after further measurement, the situation will be even more exciting, ” explains Akira Ishida of the University of Tokyo.
Theoretical predictions also seem solid, quantum electrodynamics expects to consider only the larger terms and neglect the less significant and more difficult to calculate terms. In this case, the neglected terms seem too small to justify the measures.
If the experiment and the theory are right, then the problem must be somewhere else. The possible existence of a new particle seems unlikely, it would have appeared in previous experiments. This leaves scientists in doubt and looking for an answer, as physicist David Cassidy, co-author of the study says: “There will certainly be something surprising, we just don’t know what it is. “