论文标题
$ x（6900）$的性质部分波浪分解$ j/ψj/ψ$散射
Nature of the $X(6900)$ in partial wave decomposition of $J/ψJ/ψ$ scattering
论文作者
论文摘要
在这封信中，我们对耦合通道散射幅度进行部分波分解，$ J/ψJ/ψ$ - $ J/ψψ（2S）$ - $ J/ψψ（3770）$，以研究共振出现在这些过程中。有效的Lagrangians用于描述四个诱人的媒介介子的相互作用，并将散射幅度计算为近级领先的顺序。进行部分波的投影，并通过padé近似实现单位化。然后，我们将振幅拟合到由LHCB测量的$ J/ψJ/ψ$不变的质谱，并确定未知耦合。 $ X（6900）$的极参数被提取为$ M = 6861.0^{+6.3} _ { - 8.8} $ 〜Mev和$γ= 129.0^{+5.6} _ { - 3.4} $ 〜Mev。我们的分析表明，其量子数更喜欢$ 0^{++} $。极点计数规则和相移表明它是正常的Breit-wigner共振，因此应该是紧凑的四夸克。
In this letter, we perform partial wave decomposition on coupled-channel scattering amplitudes, $J/ψJ/ψ$-$J/ψψ(2S)$-$J/ψψ(3770)$, to study the resonance appears in these processes. Effective Lagrangians are used to describe the interactions of four charmed vector mesons, and the scattering amplitudes are calculated up to the next-to-leading order. Partial wave projections are performed, and unitarization is implemented by Padé approximation. Then we fit the amplitudes to the $J/ψJ/ψ$ invariant mass spectra measured by LHCb and determine the unknown couplings. The pole parameters of the $X(6900)$ are extracted as $M=6861.0^{+6.3}_{-8.8}$~MeV and $Γ=129.0^{+5.6}_{-3.4}$~MeV. Our analysis implies that its quantum number prefers to be $0^{++}$. The pole counting rule and phase shifts show that it is a normal Breit-Wigner resonance and, hence, should be a compact tetraquark.
