$N\Omega$ dibaryon from lattice QCD near the physical point

Abstract

The nucleon($N$)-Omega($\Omega$) system in the S-wave and spin-2 channel (${}^5$S${}_2$) is studied from the (2+1)-flavor lattice QCD with nearly physical quark masses ($m_{\pi }\simeq 146$~MeV and $m_K\simeq 525$~MeV). The time-dependent HAL QCD method is employed to convert the lattice QCD data of the two-baryon correlation function to the baryon-baryon potential and eventually to the scattering observables. The $N\Omega$(${}^5$S${}_2$) potential, obtained under the assumption that its couplings to the D-wave octet-baryon pairs are small, is found to be attractive in all distances and to produce a quasi-bound state near unitarity: In this channel, the scattering length, the effective range and the binding energy from QCD alone read $a_0=5.30(0.44){(}_{-0.01}^{+0.16})$~fm, $r_{\mathrm{eff}}=1.26(0.01){(}_{-0.01}^{+0.02})$~fm, $B=1.54(0.30){(}_{-0.10}^{+0.04})$~MeV, respectively. Including the extra Coulomb attraction, the binding energy of $p{\Omega }^{-}$(${}^5$S${}_2$) becomes $B_{p{\Omega }^{-}}=2.46(0.34){(}_{-0.11}^{+0.04})$~MeV. Such a spin-2 $p{\Omega }^{-}$ state could be searched through two-particle correlations in $p$-$p$, $p$-nucleus and nucleus-nucleus collisions.

Comments: 16 pages, 6 figures, a reference added