Mercoledì 14/02/2024 alle ore 15:00 in Aula Caianiello,

il Prof. Luciano Maiani terrà il seguente seminario: 

Titolo: " Radiative decays of X(3872) in psi e psi' "

Abstract: 

Radiative decays X --> psi(1S) + gamma and X --> psi(2S) + gamma might be expected to have a ratio of branching fractions following the phase space volumes ratio. However, data suggest the opposite, indicating a value for R=B(X --> psi^prime + gamma) / B(X --> psi +gamma) consistently larger than one. We present a calculation of R for both a compact Born-Oppenheimer cc-bar q-qbar state and a DD^* molecule. In the former case R~1 or larger is found, a value to be confronted with forthcoming high statistics data analyses. In the molecular picture, with D and D^* mesons described by the universal wave function used by Voloshin, Braaten and Kusunoki, we find that R would be of order 10^{^-2}. A more precise experimental measure would be extremely helpful in clarifying the true nature of the X(3872). This work allows to discriminate between the molecular and compact interpretations.