e+e−→K+K−π+π− , K+K−π0π0 and K+K−K+K− cross sections measured with initial-state radiation

Le résumé fourni par la source

We study the processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$, ${K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$ and ${K}^{+}{K}^{\ensuremath{-}}{K}^{+}{K}^{\ensuremath{-}}\ensuremath{\gamma}$, where the photon is radiated from the initial state. About 34 600, 4400 and 2300 fully reconstructed events, respectively, are selected from $232\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of BABAR data. The invariant mass of the hadronic final state defines the effective ${e}^{+}{e}^{\ensuremath{-}}$ center-of-mass energy, so that the ${K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\gamma}$ data can be compared with direct measurements of the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ reaction; no direct measurements exist for the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ or ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}{K}^{+}{K}^{\ensuremath{-}}$ reactions. Studying the structure of these events, we find contributions from a number of intermediate states, and we extract their cross sections where possible. In particular, we isolate the contribution from ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\phi}(1020){f}_{0}(980)$ and study its structure near threshold. In the charmonium region, we observe the $J/\ensuremath{\psi}$ in all three final states and several intermediate states, as well as the $\ensuremath{\psi}(2S)$ in some modes, and measure the corresponding branching fractions. We see no signal for the $Y(4260)$ and obtain an upper limit of ${\mathcal{B}}_{Y(4260)\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}}\ifmmode\cdot\else\textperiodcentered\fi{}{\ensuremath{\Gamma}}_{ee}^{Y}<0.4\text{ }\text{ }\mathrm{eV}$ at 90% C.L.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.