Spin-1 diquark contributing to the formation of tetraquarks in light mesons

Kim, Hungchong (Research Institute of Basic Science, Korea Aerospace University, 0000 0000 9881 3149, 412-791, Goyang, Korea) ; Cheoun, Myung-Ki (Department of Physics, Soongsil University, 0000 0004 0533 3568, 156-743, Seoul, Korea) ; Kim, K. S. (School of Liberal Arts and Science, Korea Aerospace University, 0000 0000 9881 3149, 412-791, Goyang, Korea)

20 March 2017

Abstract: We apply a mixing framework to the light-meson systems and examine tetraquark possibility in the scalar channel. In the diquark–antidiquark model, a scalar diquark is a compact object when its color and flavor structures are in ( 3¯c , 3¯f ). Assuming that all the quarks are in an S -wave, the spin-0 tetraquark formed out of this scalar diquark has only one spin configuration, |J,J12,J34⟩=|000⟩ , where J is the spin of the tetraquark, J12 the diquark spin, J34 the antidiquark spin. In this construction of the scalar tetraquark, we notice that another compact diquark with spin-1 in ( 6c , 3¯f ) can be used although it is less compact than the scalar diquark. The spin-0 tetraquark constructed from this vector diquark leads to the spin configuration |J,J12,J34⟩=|011⟩ . The two configurations, |000⟩ and |011⟩ , are found to mix strongly through the color–spin interaction. The physical states can be identified with certain mixtures of the two configurations which diagonalize the hyperfine masses of the color–spin interaction. Matching these states to two scalar resonances a0(980),a0(1450) or to K0∗(800),K0∗(1430) depending on the isospin channel, we find that their mass splittings are qualitatively consistent with the hyperfine mass splittings, which can support their tetraquark structure. To test our mixing scheme further, we also construct the tetraquarks for J=1,J=2 with the spin configurations |111⟩ and |211⟩ , and we discuss possible candidates in the physical spectrum.

Published in: EPJC 77 (2017) 173
Published by: Springer/Società Italiana di Fisica
DOI: 10.1140/epjc/s10052-017-4736-6
License: CC-BY-3.0

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