On the structures of new scalar resonances Tacs0 (2900)++ and Ta cs0 (2900)0

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 M++ = D-s*(+) rho(+) and M-0 = D-s*(+) rho(-) of conventional vector mesons, respectively. The mass m and current coupling f of the molecule M++ are calculated using a 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 +/- 135) MeV, permits us to consider the molecule M++ as one of the possible models of the resonance T-cs0(a)(2900)(++). Because the second structure T-cs0(a)(2900)(0) partner of the doubly charged state, it should have a mass close to m.