Search for hidden charm states decaying into J/ psi or psi ' plus pions.

A search has been made in 300 GeV/c π±- and proton-Li interactions for production of states that decay into J/ψ or ψ’ plus one or two pions. A 2.5σ enhancement in the J/ψ π0 spectrum, possibly the recently reported 1P1 state of charmonium, is observed at a mass of 3.527 GeV/c2. In the J/ψ plus two pion mass spectrum, we report, together with the expected ψ’→J/ψ π+π−, the tentative observation of a structure at a mass of 3.836 GeV/c2. No enhancements are seen in the J/ψ π±π±, J/ψ π±π0, J/ψ π±, or ψ’ π± mass spectra.