On electromagnetic and QCD isospin–breaking corrections to the energy level displacement of the ground state of kaonic hydrogen

We calculate electromagnetic and QCD isospin–breaking corrections to the energy level displacement of the ground state of kaonic hydrogen. Our results, calculated within a quantum field theoretic and relativistic covariant approach, agree well with those obtained by Meißner, Raha and Rusetsky within the non–relativistic effective Lagrangian approach based on Chiral Perturbation Theory by Gasser and Leutwyler. PACS: 36.10.–k, 11.10.Ef, 11.55.Ds, 13.75.Jz E–mail: [email protected], Tel.: +43–1–58801–14261, Fax: +43–1–58801–14299 Permanent Address: State Polytechnic University, Department of Nuclear Physics, 195251 St. Petersburg, Russian Federation E–mail: [email protected] E–mail: [email protected], Tel.: +43–1–58801–14261, Fax: +43–1–58801–14299 E–mail: [email protected] E–mail: [email protected], State Polytechnic University, Department of Nuclear Physics, 195251 St. Petersburg, Russian Federation E–mail: [email protected] State Polytechnic University, Department of Nuclear Physics, 195251 St. Petersburg, Russian Federation E–mail: [email protected]