Speaker
Description
In this study, we present a lattice QCD analysis of the $J^P=1^+$
diquark within the charmed baryon $Σ_c^{++}(uuc)$.
Treating $Σ_c$ as a bound state of a charm quark and a uu $1^+$ diquark,
we utilize an extended HAL QCD potential method to determine both the
mass of the $1^+$ diquark and the potential between the charm quark and
the $1^+$ diquark.
Unlike the standard HAL QCD approach, the mass of the $1^+$ diquark is a
non-trivial quantity that cannot be straightforwardly obtained from
the two-point correlator due to the color confinement.
To address this, we employ the Kawanai-Sasaki extension of the HAL QCD
method, originally developed to self-consistently determine the charm
quark mass alongside the ccbar potential within the HAL QCD framework.
Our lattice QCD Monte Carlo calculations are performed using 2+1
flavor QCD gauge configurations on a $L^3 × T = 32^3 × 64$ lattice,
generated by the PACS-CS collaboration, corresponding to a pion mass
of approximately 700 MeV.
We find a spin-independent central potential of Cornell-type along
with a short-ranged, spin-dependent central potential, which takes the
form of a smeared delta-function.
The resulting mass of the $1^+$ diquark is about 867 MeV, slightly lower
than anticipated. This discrepancy is likely due to statistical noise
in the Nambu-Bethe-Salpeter wave functions at long distances.
