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Renormalization group analysis of nuclear current operators

A Wilsonian renormalization group (WRG) equation for nuclear current operators in two-nucleon systems is derived. Nuclear current operators relevant to low-energy Gamow-Teller transitions are analyzed using the WRG equation. We employ the axial two-body current operators from phenomenological models and heavy-baryon chiral perturbation theory, which are quite different from one another in describing small scale physics. After reducing the model space of the operators using the WRG equation, we find that there still remains a significant model dependence at Λ= 200 MeV, where Λis the sharp cutoff specifying the size of the model space. A model independent effective current operator is found at a rather small cutoff value, Λ= 70 MeV. By simulating the effective current operator at Λ=70 MeV, we obtain a current operator based on a pionless theory, thereby arguing an equivalence relation between nuclear current operators of phenomenological models and those of effective field theories.