$d^\ast (2380)$ dibaryon from lattice QCD

TL;DR

This study uses lattice QCD simulations with heavy pion masses to investigate the $d^igstar(2380)$ dibaryon resonance, revealing a strong short-range attraction leading to a quasi-bound state and analyzing its decay properties.

Contribution

First lattice QCD calculation of the $d^igstar(2380)$ dibaryon potential, demonstrating a strong attraction and quasi-bound state formation at heavy pion masses.

Findings

Strong short-range attraction in $ ext{Delta} ext{Delta}$ potential

Formation of a quasi-bound state with 25-40 MeV binding energy

Decay width to $NN$ is kinematically suppressed

Abstract

The $\Delta\Delta$ dibaryon resonance $d^\ast (2380)$ with $(J^P, I)=(3^+, 0)$ is studied theoretically on the basis of the 3-flavor lattice QCD simulation with heavy pion masses ($m_\pi =679, 841$ and $1018$ MeV). By using the HAL QCD method, the central $\Delta$-$\Delta$ potential in the ${}^7S_3$ channel is obtained from the lattice data with the lattice spacing $a\simeq 0.121$ fm and the lattice size $L\simeq 3.87$ fm. The resultant potential shows a strong short-range attraction, so that a quasi-bound state corresponding to $d^\ast (2380)$ is formed with the binding energy $25$-$40$ MeV below the $\Delta\Delta$ threshold for the heavy pion masses. The tensor part of the transition potential from $\Delta\Delta$ to $NN$ is also extracted to investigate the coupling strength between the $S$-wave $\Delta\Delta$ system with $J^P=3^+$ and the $D$-wave $NN$ system. Although the transition potential is strong at short distances, the decay width of $d^\ast (2380)$ to $NN$ in the $D$-wave is kinematically suppressed, which justifies our single-channel analysis at the range of the pion mass explored in this study.