PHYSICAL REVIEW D, cilt.113, sa.3, 2026 (SCI-Expanded, Scopus)
We employ the Born-Oppenheimer approximation to the Tacs & strns;0(2900)0 and Tacs & strns;0(2900)++ states observed by the LHCb Collaboration and study mass spectrum and root-mean-square radius values. For this purpose, we use the dynamical diquark model. We assume that a strange quark is heavy for the usage of the Born-Oppenheimer approximation. Our results strongly indicate that the Tacs & strns;0(2900) states are best described as composed of axial-vector (spin-1) diquark pairs. Furthermore, the calculated root-mean-square radius, /r2)1/2 approximate to 0.70-0.80 fm, which is significantly less than 1 fm, provides compelling evidence that these are compact tetraquarks rather than loosely bound hadronic molecules.