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 $m$.
Categories: hep-ph hep-ex hep-lat