Testing the tetraquark structure for the X resonances in the low-lying region

X共鳴粒子の低エネルギー領域でのテトラクォーク構造としての分析

Kim, H.*; Kim, K. S.*; Cheoun, M.-K.*; 慈道 大介*; 岡 眞   

Kim, H.*; Kim, K. S.*; Cheoun, M.-K.*; Jido, Daisuke*; Oka, Makoto

チャームを含むテトラクォーク状態であるX共鳴に関して、カラースピン相互作用によるスペクトルの分析を行った。スピンが0, 1, 2の状態について超微細構造を計算し、2個のスピン0状態と2個のスピン1状態の固有状態を求めた。X(3872)の質量をインプットとして、他の状態の質量の予言を与え、X(3823), X(3900), X(3940)などの量子状態を決めた。パラメータはすでにDおよびBメソンのスペクトルで決めた値を用い、チャームが隠れたXと無矛盾であることを示した。

Assuming four-quark structure for the resonances in low-lying region, we calculate their masses using the color-spin interaction. In specific, the hyperfine masses of the color-spin interaction are calculated for the possible states in spin-0, spin-1, spin-2 channels. The two states in spin-0 channel as well as the two states in spin-1 channel are diagonalized in order to generate the physical hyperfine masses. By matching the difference in hyperfine masses with the splitting in corresponding hadron masses and using the mass as an input, we estimate the masses corresponding to the states . We find the masses of two states in are close to those of , , and the mass of the state is close to that of . For them, the discrepancies are about MeV. This may suggest that the quantum numbers of the controversial states are . In this work, we use the same inputs parameters, the constituent quark masses and the strength of the color-spin interaction, that have been adopted in the previous work on the or -meson excited states. There, it was shown that the four-quark structure can be manifested in their excited states. Thus, our results in this work provide a consistent treatment on open- and hidden-charm mesons as far as the four-quark model is concerned.