## Spectrum of free polaron and radius of perturbation theory

- A. KlochihinA.
- / / Fiz . Tverd . Tela
- 1979

@inproceedings{TkachAnalyticPO, title={Analytic peculiarities of the polaron mass operator in the first two orders of the coupling constant}, author={Mykola Tkach and Oxana Voitsekhivska and O. Val’Chernivtsi} }

The exact analytic expression for the polaron mass operator in the second order of the coupling constant is established for the first time. It holds in the whole energy scale. The peculiarities of the mass operator are analysed. The renormalized polaron energy spectrum is obtained and analysed in this approximation.