• DOI:10.1103/PhysRevD.105.074510
• Corpus ID: 244729545

Quark-diquark potential and diquark mass from Lattice QCD

@inproceedings{Watanabe2021QuarkdiquarkPA,
  title={Quark-diquark potential and diquark mass from Lattice QCD},
  author={Kai Watanabe},
  year={2021}
}

• Kai Watanabe
• Published 30 November 2021
• Physics

We propose a new application of lattice QCD to calculate the quark-diquark potential, diquark mass and quark mass required for the diquark model. As a concrete example, we consider the Λc baryon and treat it as a charm-diquark(c-[ud]) two-body bound state. We extend the HAL QCD method to calculate the charm-diquark potential which reproduces the equal-time Nambu-BetheSalpeter wave function of the S-wave state (Λc( 1 2 + )). The diquark mass is determined so as to reproduce the difference between the S-wave and the spin-orbit averaged P-wave energies, i.e. the difference between the Λc( 1 2 + ) level and the average of the Λc( 1 2 − ) and the Λc( 3 2 − ) levels. Numerical calculations are performed on a 32 × 64 lattice with lattice spacing of a ' 0.0907 fm and the pion mass of mπ ' 700 MeV. Our charm-diquark potential is given by the Coulomb+linear (Cornell) potential where the long range behavior is consistent with the charm-anticharm potential while the Coulomb attraction is considerably smaller. This weakening of the attraction may be attributed to the diquark size effect. The obtained diquark mass is mD = 1.273(44) GeV. Our diquark mass lies slightly above the conventional estimates, namely the ρ meson mass and twice the constituent quark mass 2mN/3.