On the structures of new scalar resonances $T_{cs0}^{a}(2900)^{++}$ and $T_{cs0}^{a}(2900)^{0}$

TL;DR

This paper models the newly observed scalar resonances $T_{cs0}^{a}(2900)$ as molecular states of vector mesons, calculates their masses using sum rules, and suggests these models align with experimental data.

Contribution

It provides a molecular model for the $T_{cs0}^{a}(2900)$ resonances and computes their masses using two-point sum rules considering vacuum condensates up to dimension 8.

Findings

Mass of $T_{cs0}^{a}(2900)^{++}$ estimated as $(2917 \, ext{MeV})$

Molecular structure as $D_{s}^{ ext{*+}} ho^{+}$ is a plausible model

Masses of neutral and doubly charged states are close

Abstract

We investigate properties of the new scalar resonances $ T_{cs0}^{a}(2900)^{++}$ and $T_{cs0}^{a}(2900)^{0}$, which were recently reported by the LHCb collaboration. These states were observed as resonant structures in $D_{s}^{+}\pi^{+}$ and $D_{s}^{+}\pi^{-}$ invariant mass distributions in $B^{+}$ meson decays. We argue that $T_{cs0}^{a}(2900)^{++} $ and $T_{cs0}^{a}(2900)^{0}$ may be modeled as molecules $\mathcal{M} ^{++}=D_{s}^{\ast+}\rho^{+}$ and $\mathcal{M}^{0}=D_{s}^{\ast+}\rho^{-} $ of conventional vector mesons, respectively. The mass $m$ and current coupling $ f $ of the molecule $\mathcal{M}^{++}$ are calculated using two-point sum rule method. The sum rule analysis is performed by taking into account vacuum condensates up to dimension $8$. The obtained result for the mass, $ m=(2917 \pm 135)~\mathrm{MeV}$, permits us to consider the molecule $ \mathcal{M}^{++}$ as one of possible models of the resonance $ T_{cs0}^{a}(2900)^{++}$. Because the second structure $T_{cs0}^{a}(2900)^{0}$ is isospin partner of the doubly charged state, it should have the mass close to $m$.