Hadronic Paschen–Back effect

Abstract We find a novel phenomenon induced by the interplay between a strong magnetic field and finite orbital angular momenta in hadronic systems, which is analogous to the Paschen–Back effect observed in the field of atomic physics. This effect allows the wave functions to drastically deform. We discuss anisotropic decay from the deformation as a possibility to measure the strength of the magnetic field in high-energy heavy-ion collisions, which has not been measured experimentally. As an example we investigate charmonia with a finite orbital angular momentum in a strong magnetic field. We calculate the mass spectra and mixing ratios. To obtain anisotropic wave functions, we apply the cylindrical Gaussian expansion method. There we use different extension parameters for the parallel and transverse directions to the magnetic field.