PBAR P --> PI- PI- PI+ PI+
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Four-pion final state in anti-p p annihilations at 940 mev/c

Burns, R.R. ; Condon, P.E. ; Donahue, J. ; et al.
Nucl.Phys.B 27 (1971) 109-124, 1971.
Inspire Record 68769 DOI 10.17182/hepdata.33655

Resilts are reported on the four-pion final state from antiproton annihilations in hydrogen in the vicinity of 940 MeV/ c . The cross section for π − π − π + π + is found to be 3.6 mb. Abundant resonance production is observed, with fits indicating that quasi-two-body production constitutes approximately half the four-pion events. The model employed, which includes resonance production and Bose symmetrization, yields excellent fits to mass distributions and angular correlations.

2 data tables
Table 1

ASSUMING TOTAL AP P CROSS SECTION OF 122 MB. ERRORS INCLUDE SYSTEMATIC UNCERTAINTIES.

Table 2

ANALYSIS OF 4PION FINAL STATE. FIXED MASS AND WIDTH BREIT-WIGNER RESONANCES AND BACKGROUND FITTED TO DATA. CROSS SECTIONS CALCULATED BY PDG (COMPILATION PDG3). ERROR GIVEN IS SCATTER FROM VARIOUS FITS.


Anti-p p annihilations into four charged mesons from 1.6 to 2.2 gev/c

Davidson, J. ; Chapman, J.W. ; Green, R.W. ; et al.
Phys.Rev.D 9 (1974) 77-90, 1974.
Inspire Record 93127 DOI 10.17182/hepdata.21951

The following reactions have been analyzed: (1) p¯p→π−π−π+π+; (2) p¯p→π−π+K−K+; (3) p¯p→K−K−K+K+. Cross sections as a function of beam momentum ranging from 1.6 to 2.2 GeVc are presented. The percentage of resonance production in reaction (1) is examined using the maximum-likelihood (ML) method. The channel is dominated by ρππ and ρf production. The percentage of ρf decreases with p¯ momentum, while ρππ appears to increase. ML fits are also made to reaction (2); the reaction is dominated by K*Kπ, ϕππ, and ρKK production. An enhancement is seen in the Q region of the ππK mass spectrum at 1278 MeV, with FWHM (full width at half maximum) of 25 MeV. Six events are consistent with reaction (3). Mass spectra indicate that five events have at least one ϕ meson produced; one of these is a ϕϕ event.

3 data tables
Table 1

NORMALIZED TO KNOWN TOTAL CROSS SECTION.

Table 2

'FIT 9'. ENERGY DEPENDENCE AND EFFECT OF BOSE-EINSTEIN STATISTICS ALSO STUDIED.

Table 3

'FIT F'.


anti-p p Interactions at 2.32-GeV/c

Chen, C.K. ; Fields, T. ; Rhines, D.S. ; et al.
Phys.Rev.D 17 (1978) 42, 1978.
Inspire Record 5667 DOI 10.17182/hepdata.24405

A bubble-chamber experiment based on 304 000 events of p¯p interactions at 2.32 GeV/c is described. The film was automatically scanned and measured by the POLLY II system. Details of the data-analysis methods are given. We report results on cross sections for constrained final states, tests of C invariance, and inclusive pion and ρ0 multiplicity parameters for annihilation final states.

2 data tables
Table 1

Axis error includes +- 4/4 contribution.

Table 2

Axis error includes +- 4/4 contribution.