mesons in a magnetic field

Gubler, P.*; Hattori, Koichi*; Lee, S. H.*; Oka, Makoto   ; Ozaki, Sho*; Suzuki, Kei*   

We investigate the mass spectra of open heavy flavor mesons in an external constant magnetic field within QCD sum rules. Spectral ansatze on the phenomenological side are proposed in order to properly take into account mixing effects between the pseudoscalar and vector channels, and the Landau levels of charged mesons. The operator product expansion is implemented up to dimension-5 operators. As a result, we find for neutral mesons a significant positive mass shift that goes beyond simple mixing effects. In contrast, charged mesons are further subject to Landau level effects, which together with the mixing effects almost completely saturate the mass shifts obtained in our sum rule analysis.