Universal crossovers and critical dynamics of quantum phase transitions : A renormalization group study of the pseudogap Kondo problem

摘要: The pseudogap Kondo problem, describing a magnetic impurity embedded in an electronic environment with power-law density of states, displays continuous quantum phase transitions between free and screened moment phases. In this paper we employ renormalization group techniques to analytically calculate universal crossover functions, associated these transitions, for various observables. Quantitative agreement the results Numerical Renormalization Group (NRG) simulations is obtained temperature-dependent static zero-temperature dynamic quantities, at away from criticality. notoriously difficult realm finite-temperature low-frequency dynamics, usually inaccessible both NRG perturbative methods, show that progress can be made by suitable procedure framework Callan-Symanzik equations. Our general strategy extended other models bulk systems.