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

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.