A search for non-qq¯ mesons in central production

Kirk, Andrew (1989). A search for non-qq¯ mesons in central production. University of Birmingham. Ph.D.

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Abstract

This thesis presents a search for non-qq¯ mesons produced in the central region in the reaction pp -> Pf (X0) Ps at 300 GeV/c, where the subscripts f and s indicate the fastest and slowest particles in the laboratory respectively and X0 represents the central system that is presumed to be produced by double exchange processes. Results are presented of an analysis of the decay of X0 to K0sK±π+, K+K-K+K- and π+π-π+π-.
In the K0sK±π+ channel clear f1(1285) and f1(1420) signals are seen. A spin parity analysis shows that both are consistent with being 1++ states. The f1(1420) is found to decay only to K*K¯ and no 0-+ wave is required to describe the data. The production of the f1(1285) as a function of energy is not the same as that for the f1(1420) whose cross section is found to be constant with energy.
In the K+K-K+K- channel ΦΦ production has been observed and the ratio σ(ΦK+K-)/σ(ΦΦ) is
1.0±0.3. The cross-section for central production of ΦΦ is found to be the same at 300 GeV/c and 85 GeV/c. An angular analysis of the ΦΦ system favours JP = 2+ over 0¯.
The π+π-π+π- mass spectrum shows evidence for the f1(1285) with a mass of 1281± 1 MeV and a width of 31 ± 5 MeV. In addition there is evidence for two new enhancements at masses of 1449± 4 and 1901± 13 MeV with widths of 78± 18 and 312±61 MeV respectively. An analysis of the state at 1.45 GeV indicates that it is not a π+π-π+π- decay mode of the f1(1420) or ι/ε(1440).

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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