Mass spectrum and strong decays of tetraquark $\bar c\bar s qq$ states

TL;DR

This paper investigates the mass spectrum and decay properties of S-wave $ar car s q q$ tetraquark states using a quark model, aiming to interpret the $X_0(2900)$ and predict a new partner state.

Contribution

It provides a systematic calculation of tetraquark masses and decays, including the interpretation of $X_0(2900)$ as a tetraquark and predicts a new partner state at 2649 MeV.

Findings

The $I(J^P)=1(0^+)$ state has mass 2941 MeV and width 26.6 MeV, matching $X_0(2900)$.

A new isospin partner state at 2649 MeV with width 48.1 MeV is predicted.

Hyperfine interactions cause mixing and large mass splittings among ground states.

Abstract

We systematically study the mass spectrum and strong decays of the S-wave $\bar c\bar s q q$ states in the compact tetraquark scenario with the quark model. The key ingredients of the model are the Coulomb, the linear confinement, and the hyperfine interactions. The hyperfine potential leads to the mixing between different color configurations, as well as the large mass splitting between the two ground states with $I(J^P)=0(0^+)$ and $I(J^P)=1(0^+)$. We calculate their strong decay amplitudes into the $\bar D^{(*)}K^{(*)}$ channels with the wave functions from the mass spectrum calculation and the quark interchange method. We examine the interpretation of the recently observed $X_0(2900)$ as a tetraquark state. The mass and decay width of the $I(J^P)=1(0^+)$ state are $M=2941$ MeV and $\Gamma_X=26.6$ MeV, respectively, which indicates that it might be a good candidate for the $X_0(2900)$. Meanwhile, we also obtain an isospin partner state $I(J^P)=0(0^+)$ with $M=2649$ MeV and $\Gamma_{X\rightarrow \bar D K}=48.1$ MeV, respectively. Future experimental search for $X(2649)$ will be very helpful.