Observation of new resonant structures in $\gamma \gamma o \omega \phi$, $\phi \phi$ and $\omega \omega$

摘要

The processes $\gamma \gamma \to \omega \phi$, $\phi \phi$, and $\omega\omega$ are measured using an 870 fb$^{-1}$ data sample collected with theBelle detector at the KEKB asymmetric-energy $e^+e^-$ collider. Production ofvector meson pairs is clearly observed and their cross sections are measuredfor masses that range from threshold to 4.0 GeV. In addition to signals fromwell established spin zero and spin two charmonium states, there are clearresonant structures below charmonium threshold, which have not been previouslyobserved. We report a spin-parity analysis for the new structures and determinethe products of the $\etac$, $\chi_{c0}$, and $\chi_{c2}$ two-photon decaywidths and branching fractions.