Charmonium spectroscopy in strong magnetic fields by QCD sum rules

We address effects of strong magnetic fields on charmonium spectra by using QCD sum rules. To this end, we propose a general framework of QCD sum rules necessary for investigating any meson spectra in strong magnetic fields, that is, a consistent treatment of mixing effects in external magnetic fields. We then show charmonium spectra from QCD sum rules, and compare it with those from a hadronic effective theory.