We calculated next-to-leading-order (NLO) QCD perturbative contributions to a
JPC=0+−, dudˉuˉ tetraquark (diquark-antidiquark) correlator
in the chiral limit of massless u and d quarks. At NLO, there are four
quark self-energy diagrams and six gluon-exchange diagrams. Nonlocal
divergences were cancelled using diagrammatic renormalization. Dimensionally
regularized integrals were numerically computed using pySecDec. The combination
of pySecDec with diagrammatic renormalization establishes a valuable new
methodology for NLO calculations of QCD correlation functions. Compared to
leading-order (LO) perturbation theory, we found that NLO perturbation theory
is significant. To quantify the impact of NLO perturbation theory on physical
predictions, we computed NLO perturbative contributions to QCD Laplace,
Gaussian, and finite-energy sum rules. Using QCD sum rules, we determined upper
and lower bounds on the 0+−, dudˉuˉ tetraquark ground-state
mass, M: at NLO in perturbation theory, we found 2.2 GeV≲M≤4.2 GeV whereas, at LO, we found 2.4 GeV≲M≤4.6 GeV. This mass range suggests the possibility of mixing between
0+−, light-quark (i.e., u and d quarks) hybrid and dudˉuˉ
tetraquark states. Taking into account uncertainties in QCD parameters, we
found no evidence for a 0+−, dudˉuˉ tetraquark under 1.9 GeV.Comment: 22 pages, 13 figures. Updated version contains additional discussio