Abstract
In order to investigate the possibility of the recently observed X(5568) being a 0+ tetraquark state, we make an improvement to the study of the related various configuration states in the framework of the QCD sum rules. Particularly, to ensure the quality of the analysis, condensates up to dimension 12 are included to inspect the convergence of operator product expansion (OPE) and improve the final results of the studied states. We note that some condensate contributions could play an important role on the OPE side. By releasing the rigid OPE convergence criterion, we arrive at the numerical value for the scalar-scalar diquark-antidiquark 0+ state, which agrees with the experimental data for the X(5568) and could support its interpretation in terms of a 0+ tetraquark state with the scalar-scalar configuration. The corresponding result for the axial-axial current is calculated to be , which is still consistent with the mass of X(5568) in view of the uncertainty. The feasibility of X(5568) being a tetraquark state with the axial-axial configuration therefore cannot be definitely excluded. For the pseudoscalar-pseudoscalar and the vector-vector cases, their unsatisfactory OPE convergence make it difficult to find reasonable work windows to extract the hadronic information.
Highlights
In order to investigate the possibility of the recently observed X(5568) being a 0+ tetraquark state, we make an improvement to the study of the related various configuration states in the framework of the QCD sum rules
Stimulated by the possibility of the recently observed structure X(5568) being an ideal candidate for exotic hadrons, we present an improved QCD sum rule study to investigate whether X(5568) could be a 0+ tetraquark state
In order to ensure the quality of QCD sum rule analysis, contributions of condensates up to dimension 12 are computed to test the operator product expansion (OPE) convergence
Summary
Reported evidence for a narrow structure, referred produced in ppcollisions at center-of-mass energy. With regard to the recently observed X(5568), there have been several studies using the QCD sum rules to study its mass from the point of view of a 0+ tetraquark state [15,16,17,18,19,20], focusing on some particular configurations. It may be difficult to satisfy both the above criteria, because in some cases it may be hard to find a work window critically satisfying both rules This could become specially obvious for some multiquark states
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