Nature of the vector resonance Y(2175)
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Spectroscopic parameters and decay channels of the vector resonance Y(2175) are studied by considering it as a diquark-antidiquark state with the quark content susit. The mass and coupling of the tetraquark Y(2175) are calculated using the QCD two-point sum rules by taking into account various quark, gluon and mixed condensates up to dimension 15. Partial widths of its strong decays to phi f(0)(980), phi eta and phi eta' are computed as well. To this end, we explore the vertices Y phi f(0)(980), Y phi eta, and Y phi eta', and calculate the corresponding strong couplings by means of the QCD light-cone sum rule method. The coupling G(Y phi f) of the vertex Y phi f(0)(980) is found using the full version of this method, and by treating the scalar meson f(0)(980) as a diquark-antidiquark tetraquark state. The couplings g(Y phi eta) and g(Y phi eta'), however, are calculated by applying the soft-meson approximation to the light-cone sum rule method. Prediction for the mass of the resonance rn(Y) = (2173 +/- 85) MeV is in excellent agreement with the data of the BABAR Collaboration [Phys. Rev. D 74, 091103 (2006)], and within errors of calculations is compatible with the result reported by BESIII [Phys. Rev. D 91 , 052017 (2015)]. The full width Gamma(full) = (91.1 +/- 20.5) MeV of the Y(2175) saturated by its three strong decay channels is in a reasonable agreement with existing experimental data.