Renormalization group approach to the Fr\"ohlich polaron model:   application to impurity-BEC problem
  We develop a renormalization group approach for analyzing Fr\"ohlich polarons and apply it to a problem of impurity atoms immersed in a Bose-Einstein condensate of ultra cold atoms. Polaron energies obtained by our method are in excellent agreement with recent diagrammatic Monte Carlo calculations for a wide range of interaction strengths. We calculate the effective mass of polarons and find a smooth crossover from weak to strong coupling regimes. Possible experimental tests of our results in current experiments with ultra cold atoms are discussed. 
F. Grusdt, Y. E. Shchadilova, A. N. Rubtsov and E. Demler
cond-mat.quant-gas cond-mat.mes-hall