Analysis of the $D_0^*(2300)$ resonance from lattice QCD under chiral symmetry

Abstract

We reanalyze the lattice spectra for $I=1/2$ $D\pi$ scattering in the $A_1^+$ irreducible representation from [Phys. Rev. D 111, 014503 (2025)] to investigate the impact of chiral and SU(3) flavor symmetries in $S$-wave $D\pi$ scattering and the $D_0^*(2300)$ resonance. By fitting the phase shifts obtained via L\"uscher's formula with both traditional and chirally modified effective-range expansion and $K$-matrix parameterizations, we find that the chiral factor shifts the extracted pole mass closer to the threshold (especially for resonances) and substantially reduces the resonance width. These findings are confirmed by unitarized chiral perturbation theory through a direct fit to the lattice spectra with both the single-channel and the $D\pi$-$D\eta$-$D_s\bar{K}$ coupled-channel schemes. Once the coupled channels are incorporated, the two-pole structure of the $D_0^*(2300)$ emerges. The trajectories of the two poles are investigated by varying the pion mass.