Detailed information of the low-energy interaction between the charmonia (ηc and J/ψ) and the nucleon is indispensable for exploring the formation of charmonium bound to nuclei. In order to investigate the charmonium-nucleon interactions at low energies, we adopt two essentially different approaches in lattice QCD simulations. The charmonium-nucleon potential can be calculated from the equal-time Bethe-Salpeter amplitude through the effective Schrödinger equation. This novel method is based on the same idea originally applied for the nucleon force by Aoki-Hatsuda-Ishii. Another approach is to utilize extended Lüscher's formula with partially twisted boundary conditions, which allows us to calculate the s-wave phase shift at any small value of the relative momentum even in a finite box. We then extract model independent information of the scattering length and the effective range from the phase shift through the effective-range expansion. Our simulations are carried out at a lattice cutoff of 1/a ≈ 2 GeV in a spatial volume of (3 fm)3 with the non-perturbatively O(a)-improved Wilson fermions for the light quarks and a relativistic heavy quark action for the charm quark. Although our main results are calculated in quenched lattice calculations, we also present a preliminary full QCD result by using the 2+1 flavor gauge configurations generated by PACS-CS Collaboration. We have found that the charmonium-nucleon potential is weakly attractive at short distances and exponentially screened at large distances. We have also successfully evaluated both the scattering length and effective range from the charmonium-nucleon scattering phase shift.
|Journal||Proceedings of Science|
|Publication status||Published - 2010|
|Event||28th International Symposium on Lattice Field Theory, Lattice 2010 - Villasimius, Sardinia, Italy|
Duration: 2010 Jun 14 → 2010 Jun 19
ASJC Scopus subject areas