Speaker
Description
The $N\Omega$ system is a promising candidate for a dibaryon bound state. To enable a direct comparison between lattice QCD and experiment, we calculate the $^5S_2$ $N\Omega$ interaction in $(2+1)$-flavor lattice QCD at the physical point ($m_\pi\simeq137.1$ MeV and $m_K\simeq501.8$ MeV) with the time-dependent HAL QCD method. Because the coupling to the $D$-wave octet-octet channels is weak, a clean single-channel analysis is possible. We find that the $^5S_2$ $N\Omega$ potential is fully attractive and that a shallow (quasi-)bound state exists close to the unitary limit. From the effective range expansion, the scattering parameters of the $n\Omega$ system are $1/a_0=-0.12(3)(^{+0.02}_{-0.04})$~fm$^{-1}$ and $r_{\text{eff}}=1.27(3)(^{+0.18}_{-0.00})$~fm, and those of the $p\Omega$ system, including the Coulomb interaction, are $1/a^C_0=-0.24(2)(^{+0.03}_{-0.04})$~fm$^{-1}$ and $r^C_{\text{eff}}=1.29(3)(^{+0.18}_{-0.00})$~fm. Solving the Schr\"odinger equation, we obtain the binding energy and RMS radius: $B=0.61(^{+0.40}_{-0.29})(^{+0.60}_{-0.18})$~MeV and $\sqrt{\langle r^2\rangle}=5.69(^{+1.89}_{-1.10})(^{+1.08}_{-1.46})$~fm for $n\Omega$, and $B=1.35(^{+0.46}_{-0.37})(^{+0.71}_{-0.28})$~MeV and $\sqrt{\langle r^2\rangle}=4.27(^{+0.68}_{-0.53})(^{+0.58}_{-0.72})$~fm for $p\Omega$. The joint distribution of $B$ and $\sqrt{\langle r^2\rangle}$ reveals a strong inverse correlation, providing tighter constraints on the bound-state properties.
