New Metastable Charmonium and the $ψ'$ Anomaly at CDF

Abstract

Production of metastable charmonium states more massive than the $ψ(3685)$ is expected in models and could be the source of up to $50\%$ of the $ψ$ observed at large $p_T$ at the Tevatron.Narrow $2^{-+},2^{--} c\bar{c}$ are predicted at around 3.8GeV and radially excited $2^3P_{1,2}$ may also have suppressed hadronic widths making these states potentially extra sources of $ψ(3685)$. Colour octet components are believed to dominate $ψ$ production at the Tevatron which suggests that hybrid charmonium production may also be prominent. Estimates of hybrid production rates and branching ratios into charmonium suggest that metastable hybrids with mass $\approx$ 4GeV may play an important role in generating the observed $ψ(3685),ψ(3095)$