The new exotics Zcs(3085), Zcs(4003), Y(4230) decays and Flavour SU(3)

Abril 26, 2021
De 4:00pm hasta 5:30pm

IFT Seminar Room/Red Room

Theoretical Physics, general interest
Luciano Maiani
Università di Roma La Sapienza. Roma. Italy

IFT Seminar Room/Red Room


New data from BES III and LHCb indicate the existence of two hidden charm, open strangeness resonances, Zcs(3985) and Zcs(4003). The near degeneracy of Zcs(3985) and Zcs(4003) reproduces, in the strange sector, the situation observed with X(3872) and Zc(3900). We show that, in the tetraquark picture, the Zcs resonances, together with X(3872), X(4140) and Zc(3900), neatly fit into two nonets of flavour SU(3), with JP = 1+ and opposite charge-conjugation. The mass of  the missing element of the nonets is predicted. 
In the same framework, we have made a study of the decays of Y(4230) observed by BES III in e+e- annihilation. Results are compared with the well studied decays D∗ → D π decays, obtaining consistent results for the quark-pion coupling. We extend the discussion to the decay B -> K phi J/Psi where the signal of Zcs(4003) has been observed by LHCb.
  These results represent a significative score in favour of the tetraquark model. We discuss briefly further steps necessary to clarify the nature of the exotic states under study.