Perturbative calculation of critical exponents for the Bose-Hubbard model

Author(s): Dennis Hinrichs
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Keywords:Bose-Hubbard model, Condensate density, Superfluid density, Critical exponent
Abstract:: The process-chain approach is a powerful tool for carrying out perturbative calculations for many-body lattice systems in high order of the hopping strength. In combination with the method of the effective potential, this technique permits us to determine characteristic quantities with an accuracy far greater than that of mean-field methods. In this talk I will concentrate on the calculation of the superfluid and of the condensate density for the Bose-Hubbard model, and demonstrate how the process-chain approach can be employed for obtaining the critical exponents characterizing the system near the superfluid-to-Mott insulator quantum phase transition.