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Kim, Y.*; Oka, Makoto; Suzuki, Kei
Physical Review D, 105(7), p.074021_1 - 074021_17, 2022/04
Times Cited Count：15 Percentile：93.15(Astronomy & Astrophysics)Energy spectrum of doubly heavy tetraquarks, 
(
with 
and 
), is studied in the potential chiral-diquark model. Using the chiral effective theory of diquarks and the quark-diquark-based potential model, the 
, 
, and 
tetraquarks are described as a three-body system composed of two heavy quarks and an antidiquark. We find several bound states, while no and (deep) bound state is seen. We also study the change of the tetraquark masses under restoration of chiral symmetry.
Kim, H.*; Kim, K. S.*; Cheoun, M.-K.*; Jido, Daisuke*; Oka, Makoto
Physical Review D, 99(1), p.014005_1 - 014005_15, 2019/01
Times Cited Count：8 Percentile：44.95(Astronomy & Astrophysics)We investigate additional signatures to support the tetraquark mixing framework that has been recently proposed as a possible structure for the two nonets. We reexamine the mass ordering generated from the tetraquark nonets and show that this mass ordering is satisfied by the two nonets although the ordering in the heavy nonet is marginal. The marginal mass ordering can be regarded as another signature for tetraquarks because it can be explained partially by the hyperfine masses calculated from the tetraquark mixing framework. As a peculiar signature distinguished from the other approaches, we investigate the fall-apart coupling strengths into two vector mesons from our tetraquarks. Coupling strengths into the two-vector modes are found to enhance strongly in the heavy nonet while they are suppressed in the light nonet. The coupling ratios are found to be huge. This trend in the two-vector modes can provide another testing ground for the tetraquark mixing framework. Some experimental evidence related to the phenomena is discussed particularly from the resonances belonging to the heavy nonet.
Kim, H.*; Kim, K. S.*; Cheoun, M.-K.*; Oka, Makoto
Physical Review D, 97(9), p.094005_1 - 094005_17, 2018/05
Times Cited Count：14 Percentile：59.03(Astronomy & Astrophysics)A tetraquark mixing framework has been applied successfully to the isoscalar resonances, 
, 
, 
and 
. Tetraquarks in this framework can have two spin configurations containing either spin-0 diquark or spin-1 diquark and each configuration forms a nonet in flavor space. The two spin configurations are found to mix strongly through the color-spin interactions. Their mixtures, which diagonalize the hyperfine masses, can generate the physical resonances constituting two nonets, which, in fact, coincide roughly with the experimental observation. We identify that , are the isoscalar members in the light nonet, and , are the similar members in the heavy nonet. The complication arises because the isoscalar members of each nonet are subject to an additional flavor mixing known as Okubo-Zweig-Iizuka rule. The tetraquark mixing framework including the flavor mixing is tested for the isoscalar resonances in terms of the mass splitting and the fall-apart decay modes. The mass splitting among the isoscalar resonances is found to be consistent qualitatively with their hyperfine mass splitting strongly driven by the spin configuration mixing, which suggests that the tetraquark mixing framework works. The fall-apart modes from our tetraquarks also seem to be consistent with the experimental modes. We also discuss possible existence of the spin-1 tetraquarks that can be constructed by the spin-1 diquark.
Oka, Makoto; Wang, G.-J.*; Jido, Daisuke*
no journal, ,
I report the results of four charm quark systems in the novel confinement potential model based on QCD.
Oka, Makoto; Wang, G. J.*; Jido, Daisuke*
no journal, ,
I report the results of four charm tetra-quark states in the novel confinement potential model based on QCD.
