Recent QCD results from the BaBar experiment

Abstract

We report some of the most recent results in studying different aspects of QCD with about 500 fb$^{-1}$ of data collected by the BaBar experiment at the $e^+e^-$ $B$-factory PEP-II, located at SLAC National Accelerator Laboratory. In particular, we present the Dalitz plot analyses of the hadronic three-body $J/\psi$ decays to $\pi^+\pi^-\pi^0$, $K^+K^-\pi^0$, and $K_SK^{\pm}\pi^{\mp}$ using an isobar model and a Veneziano model. From the isobar analyses of the modes $J/\psi \rightarrow K^+K^-\pi^0$ and $J/\psi \rightarrow K_SK^{\pm}\pi^{\mp}$, a broad structure has been observed in the low-mass region of the $K\bar{K}$ invariant mass spectra and found to be consistent with the neutral and charged resonances $\rho(1450)$. Moreover, for the first time the branching fraction ratio of the decay $\rho(1450)^0 \rightarrow\pi^+\pi^-$ over $\rho(1450)^0\rightarrow K^+K^-$ is measured to be $(0.307\pm0.084\pm0.082)$. We then show the results of a search for the $B$-meson decay to four baryons $B^0\rightarrow p p \bar{p} \bar{p}$, which might help shedding some light on the mechanism of hadron fragmentation into baryons, and on the experimental difference between the inclusive branching fraction of $B$-meson decay to baryons and the sum of the exclusive baryonic $B$ decays. A signal yield of $10.4\pm4.3$ events is observed, corresponding to a statistical significance of $3\sigma$, and the upper limit is computed to be $2\times10^{-7}$ at $90\%$ confidence level.