Using a newly developed laser-microwave-laser resonance method, we observed a pair of microwave transitions between hyperfine levels of the [Formula presented] state of antiprotonic helium. This experiment confirms the quadruplet hyperfine structure arising from the interaction of the antiproton orbital angular momentum, the electron spin and the antiproton spin as predicted by Bakalov and Korobov. The measured frequencies of [Formula presented] and [Formula presented] agree with recent theoretical calculations on a level of [Formula presented].
ASJC Scopus subject areas
- Physics and Astronomy(all)