Scalar diquark mass and quark--diquark potential from lattice QCD using the potential method with a static quark

We study the scalar diquark mass and the quark–diquark potential by applying a HAL QCD-inspired potential method to a baryonic system composed of a scalar diquark and a static quark. The diquark mass is determined self-consistently by requiring that the p-wave baryonic spectrum obtained from two-point correlators be reproduced within the potential framework. Numerical calculations are performed using $2+1$ flavor QCD gauge configurations generated by the PACS-CS Collaboration on a $L^3\times T={32}^3\times 64$ lattice with $a^{-1}\approx 2.176$ GeV and the pion mass, $m_{\pi }\approx 702$ MeV. From the analysis, we obtain a scalar diquark mass which is close to the naïve constituent quark estimate $(2\mathrm{/}3)m_N$, together with a quark–diquark potential of the Cornell type (Coulomb + linear). The string tension extracted from the quark–diquark potential agrees within approximately 5% with that obtained from the static quark–antiquark potential (Wilson Loop).