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.
ASSUMING TOTAL AP P CROSS SECTION OF 122 MB. ERRORS INCLUDE SYSTEMATIC UNCERTAINTIES.
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.
We give new experimental results on ρω interference and two-body cross sections in p¯p annihilation at 2.3GeVc. These are used, together with ρω interference results from lower energies, to argue that the annihilation process is not mediated by discrete s-channel mesonic resonances in the mass range 2.1-2.6 GeV.
No description provided.
New data from a 600 000 picture exposure of the BNL 31 inch hydrogen bubble chamber to a separated antiproton beam have been analyzed to try to determine if the π + π − π + π − or π + π − π + π − π 0 final states contribute any broad or narrow structure in the T(2190) region. The resonance channel fractions determined by maximum likelihood fits are all consistent with smooth behavior through the T-region and therefore there is no significant evidence that any of these resonance channels contributes to the broad bump in the total cross section. The errors on some of the fractions, however, limit the sensitivity to ∼ 0.5 mb for enhancements in these channels.
RESONANCE CHANNEL PERCENTAGES FROM FIT TO PI+ PI- PI+ PI- FINAL STATE.
RESONANCE CHANNEL PERCENTAGES FROM FIT TO PI+ PI- PI+ PI- PI0 FINAL STATE.
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.
NORMALIZED TO KNOWN TOTAL CROSS SECTION.
'FIT 9'. ENERGY DEPENDENCE AND EFFECT OF BOSE-EINSTEIN STATISTICS ALSO STUDIED.
'FIT F'.
An analysis of the K 0 K 0 system at threshold produced in the final states p p → K S 0 K S 0 ( n π) at 700–760 MeV/ c , is presented. A simultaneous fit to the ππ phase shifts and inelasticities and to the K S 0 K S 0 effective-mass distributions using parametrizations which take into account the analytical and unitarity properties of the I = 0 S-wave amplitudes is performed. The behaviour of the eigenphases and the unphysical Riemann sheet structure for different solutions is studied.
No description provided.
FIT TO RESONANCE PRODUCTION CHANNELS IN <KS KS PI+ PI-> FINAL STATE.
FIT TO RESONANCE PRODUCTION CHANNELS IN <KS KS PI0> FINAL STATE.
A systematic study of p p and p d resonance production cross sections in non-strange annihilation channels between 1.51 and 2.90 GeV/ c has been completed. The data have been analysed in relation to the three known structures at c.m. N N energies of 2190, 2350 and 2375 MeV. Several resonance intermediate states may have broad maxima near the isopin one 2350 MeV structure. However, more data below 1.6 GeV/ c are required to better describe the background in this region before firm conclusions may be drawn.
No description provided.
No description provided.