Evidence for the decay $X(3872)\to \ddot{I}ˆ(2S){\hat{I}}^3$

Abstract

Evidence for the decay mode $X(3872)\to \ddot{I}ˆ(2S){\hat{I}}^3$ in $B^{+}\to X(3872)K^{+}$ decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton-proton collisions, corresponding to an integrated luminosity of 3fb${}^{-1}$ collected with the LHCb detector, at centre-of-mass energies of 7 and 8TeV. The ratio of the branching fraction of the $X(3872)\to \ddot{I}ˆ(2S){\hat{I}}^3$ decay to that of the $X(3872)\to J/\ddot{I}ˆ{\hat{I}}^3$ decay is measured to be $$\frac{Br(X(3872)\to \ddot{I}ˆ(2S){\hat{I}}^3)}{Br(X(3872)\to J/\ddot{I}ˆ{\hat{I}}^3)}=2.46\pm 0.64\pm 0.29,$$ where the first uncertainty is statistical and the second is systematic. The measured value agrees with expectations for a pure charmonium interpretation of the $X(3872)$ state and a mixture of charmonium and molecular interpretations. However, it does not support a pure $D{\bar{D}}^{\ast }$ molecular interpretation of the $X(3872)$state.

19 pages, 4 figures