Abstract
We study initial-state radiation events, e+ e- --> gammaISR pi+ pi- J/psi, with data collected with the BABAR detector. We observe an accumulation of events near 4.26 GeV/c2 in the invariant-mass spectrum of pi+ pi- J/psi. Fits to the mass spectrum indicate that a broad resonance with a mass of about 4.26 GeV/c2 is required to describe the observed structure. The presence of additional narrow resonances cannot be excluded. The fitted width of the broad resonance is 50 to 90 MeV/c2, depending on the fit hypothesis.
| Original language | English |
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| Pages (from-to) | 142001 |
| Number of pages | 1 |
| Journal | Physical Review Letters |
| Volume | 95 |
| DOIs | |
| Publication status | Published - 1 Sept 2005 |