Galilean-invariant effective field theory for the X(3872) at next-to-leading order

摘要

XEFT is a low-energy effective field theory for charm mesons and pions that provides a systematically improvable description of the X ( 3872 ) resonance. To simplify calculations beyond leading order, we introduce a new formulation of XEFT with a dynamical field for a pair of charm mesons in the resonant channel. We simplify the renormalization of XEFT by introducing a new renormalization scheme that involves the subtraction of amplitudes at the complex D * 0 D ˉ 0 threshold. The new formulation and the new renormalization scheme are illustrated by calculating the complex pole energy of X and the D * 0 D ˉ 0 scattering amplitude to next-to-leading order using Galilean-invariant XEFT.