Color flux-tube nature of the states $T_{cs}(2900)$ and $T_{c\bar{s}}^a(2900)$

Abstract

Inspired by the states $T_{cs0}(2900{)}^0$, $T_{cs1}(2900{)}^0$, $T_{c\bar{s}0}^a(2900{)}^0$ and $T_{c\bar{s}0}^a(2900{)}^{++}$ reported by the LHCb Collaboration, we carry out a systematical investigation on the properties of the ground and $P$-wave states $[cs][\bar{u}\bar{d}]$ and $[cu][\bar{s}\bar{d}]$ with various spin, isospin or $U$-spin, and color combinations in a multiquark color flux-tube model. Matching our results with the spin-parity and mass of the states $T_{cs0}(2900{)}^0$ and $T_{cs1}(2900{)}^0$, we can describe them as the compact states $[cs][\bar{u}\bar{d}]$ with $I(J^P)=1(0^{+})$ and $0(1^{-})$ in the model, respectively. The ground state $T_{cs0}(2900{)}^0$ is mainly made of strongly overlapped an axial-vector $[cs{]}_{{\bar{3}}_c}$ and an axial-vector $[\bar{u}\bar{d}{]}_{3_c}$. The $P$-wave state $T_{cs1}(2900{)}^0$ is dominantly consisted of a gradually separated scalar or axial vector $[cs{]}_{{\bar{3}}_c}$ and a scalar $[\bar{u}\bar{d}{]}_{3_c}$ in the shape of a dumbbell. Supposing the states $T_{c\bar{s}0}^a(2900{)}^0$ and $T_{c\bar{s}0}^a(2900{)}^{++}$ belong to the same isospin triplet, the mass of the state ${\left[[cu{]}_{{\bar{3}}_c}[\bar{s}\bar{d}{]}_{3_c}\right]}_{1_c}$ with symmetrical $U$-spin and $J^P=0^{+}$ is highly consistent with that of the states $T_{c\bar{s}0}^a(2900{)}^0$ and $T_{c\bar{s}0}^a(2900{)}^{++}$ in the model. After coupling two color configurations, the state $[cu][\bar{s}\bar{d}]$ is slightly lighter than the states $T_{c\bar{s}0}^a(2900{)}^0$ and $T_{c\bar{s}0}^a(2900{)}^{++}$. In addition, we also discuss the properties of other states in the model.

Comments: 9 pages, 4 tables, comments are welcome