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Study of the $\pi^+ \pi^+ \pi^- \pi^-$ System Centrally Produced by Incident $\pi^+$ and $p$ Beams at 85-{GeV}/$c$

The WA76 collaboration Armstrong, T.A. ; Bloodworth, I.J. ; Carney, J.N. ; et al.

Z.Phys.C 43 (1989) 55, 1989.

Inspire Record 276888 DOI 10.17182/hepdata.15434

The reactions π+p→π+(π+π+π-π-)p andpp→p(π+π+π-π-)p, where the (π+ π+ π- π-) system is centrally produced have been studied at 85 GeV/c. The π+π+π-π- mass spectrum shows evidence for thef1 (1285) meson with a mass of 1278±2 MeV and width 41±12 MeV which decays mainly through ρ0(770)π+π-. Thef1(1285) is also observed in the ηπ+π- channel. There is no significant evidence for ηππ or 4π decay modes of thef1(1420). The ρ0ρ0 production is found to be small. A Dalitz plot analysis of the 3π system shows evidence fora2 (1320) production and for a large contribution of theJPC=1++ ρπ wave.

3 data tables

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Multiplicity Distribution in $K^+$ Al and $K^+$ Au Collisions at 250-{GeV}/c and a Test of the Multiple Collision Model.

The EHS/NA22 collaboration Ajinenko, I.V. ; Belokopytoy, Yu. A. ; Bialkowska, H. ; et al.

Z.Phys.C 42 (1989) 377-385, 1989.

Inspire Record 281815 DOI 10.17182/hepdata.15530

Multiplicity distributions, observed inK+ interactions with Al and Au nuclei at 250 GeV/c incident momentum are presented. They are analyzed in the framework of multiple collisions of the incident particle inside a nucleus. The probability distribution of the number of grey tracks is well described by the model of Andersson et al., if a negative binomial distribution is assumed for the distribution of the number of grey protons produced per elementary collision instead of the usual geometrical distribution. The analysis of the average and dispersion of the charge multiplicity distribution supports the validity of the multiple collision model, including results on correlations between forward and backward multiplicities.

4 data tables

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A Study of $K^0_S$, $\Lambda$ and $\bar{\Lambda}$ Production in 60-{GeV} and 200-{GeV} Per Nucleon O Au and $p$ Au Collisions With a Streamer Chamber Detector at the {CERN} {SPS}

The NA35 collaboration Bamberger, A. ; Bartke, J. ; Bialkowska, H. ; et al.

Z.Phys.C 43 (1989) 25, 1989.

Inspire Record 276686 DOI 10.17182/hepdata.15456

The production of neutral strange particlesKso, Λ and$\bar \Lambda $ has been studied in 60 and 200 GeV per nucleon OAu and pAu collisions with the streamer chamber vertex spectrometer of the NA35 experiment at the CERN-SPS accelerator. Ratios of neutral strange particle production to negatively charged particle production in selected regions of phase space were measured to be the same in OAu and pAu reactions. The rates of strange particle production in central OAu collisions are about a factor of 16 higher than in pAu collisions when compared in the same regions of phase space. If an enhancement of strange particle production in OAu collisions relative to pAu collisions is considered to be a signature for quark-gluon plasma formation, no evidence supporting it is observed. The experimental results are compared to the Lund FRITIOF model.

22 data tables

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