New metastable charmonium and the ψ′ anomaly at CDF

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 pT at the Tevatron. Narrow 2−+, 2−− cc are predicted at around 3.8 GeV and radially excited 23P1,2 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 ≈4 GeV may play an important role in generating the observed ψ (3685), ψ (3095)