Diffusion Monte Carlo calculation of compact $T_{cs0}$ and $T_{c\bar{s}0}$ tetraquarks

TL;DR

This study employs diffusion Monte Carlo calculations within a constituent quark model to predict the masses of newly observed tetraquark states, revealing their bound configurations and isospin assignments.

Contribution

It introduces a direct eigenvector approach for compact tetraquarks, providing mass predictions and isospin assignments consistent with experimental data.

Findings

Identifies two bound configurations for each tetraquark state.

Predicts masses of excited flavor states matching LHCb observations.

Assigns isospin I=1 to the $T_{cs0}$ tetraquark.

Abstract

The LHCb collaboration amplitude analysis of the decays $B^+ \to D^+ D^- K^+$, $B^+ \to D^- D_s^+ \pi^+$, and $B^0 \to \bar{D}^0 D_s^+ \pi^-$ suggested the existence of two new resonant $J^P=0^+$ states with minimum quark content $\bar{u} \bar{d} s c$ and $\bar{s} \bar{u} d c$/$\bar{s} \bar{d} u c$, named $T_{cs0}$ and $T_{c\bar{s}0}$, respectively. In this work, we used the diffusion Monte Carlo (DMC) method to compute the masses of those tetraquarks within the framework of the constituent quark model. We describe the systems as compact structures, not as diquark/antidiquark or meson/meson arrangements. In this context, compact means that we used directly the eigenvectors of the spin, color and flavor operators without any splitting and/or (re)combination of smaller units. This allows us to deduce the existence of two distinct bound configurations for each composition, corresponding to ground and excited flavor states. In both cases, the excited flavor states are the ones with masses comparable to the ones observed by LHCb. In addition, our analysis allows us to assign unambiguously an isospin value of $I$=1 to the experimentally obtained $T_{cs0}$ tetraquark.