An analysis on doubly bottom molecular tetraquarks composed of $H_{(s)}$ and $T_{(s)}$ doublets
Jun-Chao Su, Qing-Fu Song, Qi-Fang Lü, Jingya Zhu
TL;DR
This work investigates doubly bottom molecular tetraquarks formed from the $H_{(s)}$ (S-wave) and $T_{(s)}$ (P-wave) bottom-meson doublets using a one-boson-exchange framework and Gaussian Expansion Method. By solving coupled-channel Schrödinger equations with $S$-$D$ wave mixing and a regulator $\Lambda\sim 1$ GeV, it predicts several loosely bound states in the $H_{(s)}\bar{T}_{(s)}$ and $H_{(s)}T_{(s)}$ sectors, notably in the $I=0$ channels such as $I(J^{PC})=0(1^{--})$, $0(1^{-+})$, and $0(2^{-{\pm}})$. The bottom-strange sectors show no viable molecular candidates at this scale, while the non-strange sectors host bound states in channels like $B\bar{B}_{1}$, $B\bar{B}^{*}_{2}$, $B^{*}B_{1}$, and $B^{*}\bar{B}^{*}_{2}$ with binding energies of a few tenths to several MeV. These predictions provide concrete targets for experimental exploration at LHCb and Belle II and illustrate how isospin and tensor forces shape hidden-bottom molecular formation.
Abstract
In this work, we investigate the doubly bottom $H_{(s)}\bar{T}_{(s)}$ and $H_{(s)}T_{(s)}$ systems by adopting the one-boson-exchange model, where $H_{(s)}$ and $T_{(s)}$ represent $S$-wave $B^{(*)}_{(s)}$ and $P$-wave $B^{(*)}_{(s)1,2}$ doublets, respectively. For the $H\bar{T}$ systems, we predict some loosely bound states in the $I(J^{PC})=0(1^{-\pm})$ $B\bar{B}_{1}$, $I(J^{PC})=0(2^{-\pm})$ $B\bar{B}_{2}^{*}$, $I(J^{PC})=0(1^{-\pm})$ $B^*\bar{B}_{1}$ and $I(J^{PC})=0(2^{-\pm})$ $B^*\bar{B}_{2}^{*}$ channels, which are the most promising hidden bottom molecular tetraquarks. For the $HT$ systems, the $B^*B_1$ channels with quantum numbers $I(J^P) = 0(1^{-}), 0(2^{-})$ and the $B^*B_2^*$ channels with $I(J^P) = 0(2^{-})$ are also likely candidates for forming molecular tetraquarks. In contrast, no molecular candidates have been identified in the bottom-strange sectors. One can hope that our predictions will provide valuable insights to the LHCb and Belle II Collaborations as they continue to explore this fascinating field through experimental research.