Low-energy $DD$ scattering in lattice QCD

We present the first lattice QCD calculation of single-channel $DD$ scattering with quantum numbers $I(J^P)=1(0^{+})$ and $0(1^{-})$. The calculation is performed on the $2+1$ flavor Wilson-Clover ensembles with a lattice spacing $a\simeq 0.077$ fm and two different pion masses, $m_{\pi }\simeq 207$ and $305$ MeV. The scattering parameters are determined using the Lüscher’s finite volume method. Our results indicate weak repulsive interaction in the $1(0^{+})$ channel and slightly attractive interaction in the $0(1^{-})$ channel. The $S$-wave isovector $DD$ scattering length and effective range, extrapolated to the physical pion mass, are $(-0.26\pm 0.05)$ fm and $(-5.5\pm 2.1)$ fm, respectively.