Heavy-light diquark masses from QCD sum rules and constituent diquark models of tetraquarks

Understand

Diquarks with $J^{P}=0^{\pm}$, $1^{\pm}$ containing a heavy (charm or bottom) quark and a light quark are investigated using QCD Laplace sum rules.

• Masses are determined using appropriately constructed gauge invariant correlation functions, including for the first time next-to-leading order perturbative contributions.
• The $J^P=0^+$ and $1^+$ charm-light diquark masses are respectively found to be 1.86$\pm$0.05 GeV and 1.87$\pm$0.10 GeV, while those of the $0^+$ and $1^+$ bottom-light diquarks are both determined to be 5.08$\pm$0.04 GeV.
• The sum rules derived for heavy-light diquarks with negative parity are poorly behaved and do not permit unambiguous mass predictions, in agreement with previous results for negative parity light diquarks.