Charmonium Production at FNAL-E835 - Triplet P States

Abstract

Fermilab experiment E835 has done an extensive set of studies on charmonium triplet P states. The most precise measurements on mass and total width come indeed from charmonium spectroscopy by direct formation of $c\bar{c}$ states in $\bar{p}p$ annihilations. Results on both partial widths and higher multipoles radiative transitions $χ_{cJ} \to J/ψγ\to γe^+ e^-$ are given, together with the $γγ$ widths of $χ_{c0}$ and $χ_{c2}$. For the first time in hadronic charmonium production, hadronic annihilation channels ($π^0 π^0$ and $ηη$) have been clearly identified at the $χ_{c0}$ resonance.