High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph)
journal:
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date:
2023-12-02 00:00:00
Abstract
We investigate the $P$-wave states $T^-_{bb}$ in the isospin singlet and three excited modes (excitation occurring in the diquark $[bb]^{s_1}_{c_1}$ ($\rho_1$-mode), antidiquark $[\bar{u}\bar{d}]^{s_2}_{c_2}$ ($\rho_2$-mode) or between them ($\lambda$-mode)) from diquarks in a quark model. We analyse the dynamical behaviors of the diquark $[bb]^{s_1}_{c_1}$, antidiquark $[\bar{u}\bar{d}]^{s_2}_{c_2}$ and their correlations in the states $T^-_{bb}$ by decomposing the interactions from various sources in the model. The absolute dominant color-spin configuration, more than $99\%$, in the $\rho_1$-mode with $1^1P_1$ is $[bb]^0_{\bar{\mathbf{3}}}[\bar{u}\bar{d}]^0_{\mathbf{3}}$. Its energy is lower about $18$ MeV than the threshold $\bar{B}\bar{B}$ so that it can establish a compact bound state. The chromomagnetic and meson-exchange interactions in the antidiquark $[\bar{u}\bar{d}]^0_{\mathbf{3}}$ are responsible for its binding mechanism. Other two excited modes are higher than their respective threshold.