PhD Dissertation Defense
A Partial Wave Analysis of Proton-Antiproton Annihilation Above Threshold for ΦΦ Production in the JETSET Experiment
UConn Physics Department
The JETSET experiment (PS202) conducted at CERN was designed to search for gluonic resonances in the mass range between 2.14 and 2.43 GeV using the channel (p,pbar) --> 4K±. This channel is OZI suppressed, thus any observed enhancement of the cross section above a level consistent with the OZI rule could indicate possible resonating gluonic degrees of freedom. In fact, the measured cross section is two orders of magnitude larger than the OZI prediction and shows an enhancement centered near 2.2 GeV of width 50-100 MeV. A partial wave analysis (PWA) has been conducted in order to search for the dominant partial waves. The formalism and methods of this PWA will be fully discussed. This analysis has revealed the dominance of Jpc = 2++ together with a significant Jpc = 4++ component. Because the Φ resonance is only 4 MeV wide, the PWA is relatively insensitive to the presence of competing channels coupling to the 4K± final state. The partial wave analysis was carried out including a non-resonant 4K± phase-space component added incoherently to the ΦΦ intensity to account for the background beneath the ΦΦ peak observed in the Dalitz plot. As a test of the sensitivity of the PWA results to this background treatment, the analysis was repeated including a contribution from the (p,pbar) --> f0f0 --> 4K± intermediate state added coherently to the ΦΦ waves, in addition to the incoherent phase-space background. The addition of the f0f0 channel improves the overall quality of the fit, but the ΦΦ results are mostly unaffected. In the 2.2 GeV region, the cross section is dominated by 2++ΦΦ waves, but no clear evidence of a narrow resonance is observed.
Friday, February 17, 2006
Gant Science Complex