Abstract Polaron properties in magnetic fields of arbitrary strengths are studied in the framework of an improved Landau‐Pekar approach. General expressions of the ground state energy and longitudinal effective mass are given. It is shown that the introduction of the electron‐phonon correlation effects in Landau‐Pekar's approximation leads to a 10% lower value of the longitudinal effective mass. The correlation effects are reduced when a high magnetic field is switched on.
