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

TL;DR

This paper models the $T_{cs}(2900)$ and related states as compact multiquark flux-tube configurations, matching their observed properties and predicting their internal structure and mass spectrum.

Contribution

It provides a systematic flux-tube model analysis of these states, describing their spin, isospin, and color configurations, and offers insights into their internal quark arrangements and mass predictions.

Findings

States $T_{cs0}(2900)^0$ and $T_{cs1}(2900)^0$ are described as compact multiquark states.

The model predicts the internal structure and dominant color configurations of these states.

Mass predictions are consistent with experimental observations for certain configurations.

Abstract

Inspired by the states $T_{cs0}(2900)^0$, $T_{cs1}(2900)^0$, $T^a_{c\bar{s}0}(2900)^{0}$ and $T^a_{c\bar{s}0}(2900)^{++}$ 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 $[cs]_{\bar{\mathbf{3}}_c}$ and an axial-vector $[\bar{u}\bar{d}]_{\mathbf{3}_c}$. The $P$-wave state $T_{cs1}(2900)^0$ is dominantly consisted of a gradually separated scalar or axial vector $[cs]_{\bar{\mathbf{3}}_c}$ and a scalar $[\bar{u}\bar{d}]_{\mathbf{3}_c}$ in the shape of a dumbbell. Supposing the states $T^a_{c\bar{s}0}(2900)^{0}$ and $T^a_{c\bar{s}0}(2900)^{++}$ belong to the same isospin triplet, the mass of the state $\left [[cu]_{\bar{\mathbf{3}}_c}[\bar{s}\bar{d}]_ {\mathbf{3}_c}\right ]_{\mathbf{1}_c}$ with symmetrical $U$-spin and $J^P=0^+$ is highly consistent with that of the states $T^a_{c\bar{s}0}(2900)^{0}$ and $T^a_{c\bar{s}0}(2900)^{++}$ in the model. After coupling two color configurations, the state $[cu][\bar{s}\bar{d}]$ is slightly lighter than the states $T^a_{c\bar{s}0}(2900)^{0}$ and $T^a_{c\bar{s}0}(2900)^{++}$. In addition, we also discuss the properties of other states in the model.