X(2900) in a chiral quark model

Abstract

Recently, the LHCb Collaboration reported their observation of the first two fully open-flavor tetraquark states named $X_0(2900)$ and $X_1(2900)$ with unknown parity. Inspired by the report, we consider all of possible four-quark candidates of $X(2900)$ including molecular structure and diquark structure in a chiral quark model with the help of Gaussian expansion method. Two different structures coupling is also considered. To identify the genuine resonances, real-scaling method (stabilization method) was employed. The results show that no candidate of $X(2900)$ is founded in $00^{+}$ and $01^{+}$ $cs\bar{q}\bar{q}$ system below the threshold of $D^{\ast }{\bar{K}}^{\ast }$, while there are two states in the $P$-wave excited $cs\bar{q}\bar{q}$ system, $D_1\bar{K}$ and $D_J\bar{K}$, which could be candidates of $X(2900)$. In this way, we assign negative parity to $X_1(2900)$, and $X_0(2900)$ maybe a resonance state above the threshold of $D^{\ast }{\bar{K}}^{\ast }$, more calculation is needed.

7 pages, 4 figures