Measurement of the Branching Ratio gamma (anti-p p --> e+ e-) / gamma (anti-p p --> Total) in anti-Proton-Proton Annihilation at Rest

Bassompierre, G. ; Binder, G. ; Dalpiaz, P. ; et al.
Phys.Lett.B 64 (1976) 475-478, 1976.
Inspire Record 109375 DOI 10.17182/hepdata.27616

Analyzing a sample of 220 000 events from an experiment still in progress at the CERN Proton Synchrotron (PS), 60 pairs of electrons with an energy above 700 MeV have been observed. The electrons, produced by annihilation of antiprotons stopped in a liquid-hydrogen target, are detected with optical spark chambers and scintillation counters. Twenty-nine out of these 60 pairs have been found to be collinear; normalizing with respect to the hadronic two-body channels π + π − and K + K − , a braching ratio B ee =Γ( p ̄ p → e + e − )/Γ( p ̄ p → total ) = (3.2 ± 0.9) × 10 −7 has been obtained

1 data table

No description provided.


Search for Structures in the $\bar{p} p \to \pi^+ \pi^-$ and $\bar{p} p \to K^+ K^-$ Cross-sections Between 360-{MeV}/$c$ and 760-{MeV}/$c$

Sugimoto, Y. ; Sudou, M. ; Fujii, T. ; et al.
Phys.Rev.D 37 (1988) 583, 1988.
Inspire Record 252971 DOI 10.17182/hepdata.38415

Cross sections have been measured for the reactions p¯p→π+π− and K+K− at 15 incident-beam momenta between 360 and 760 MeV/c with significantly better statistics than previous experiments in this momentum region. No significant structure has been found in either channel. The values of 90%-confidence-level upper limits for the possible resonance cross sections are given.

31 data tables
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Measurement of $\bar{p} p$ Annihilation Cross-sections Into Charged Particles in the Momentum Range 374-{MeV}/$c$ - 680-{MeV}/$c$

Sai, F. ; Sakamoto, S. ; Yamamoto, S.S. ;
Nucl.Phys.B 213 (1983) 371-389, 1983.
Inspire Record 11837 DOI 10.17182/hepdata.33967

p p annihilation cross sections into 2-, 4- and 6-prong topologies, and the exclusive annihilation cross sections for the π + π − , K + K − , π + π − π 0 , π + π + π − π − , π + π + π − π − π 0 , π + π + π + π − π − π − , and π + π + π + π − π − π − π 0 channels in the momentum range 374–680 MeV/ c were measured. No prominent structure was observed in the momentum dependence of any of the above cross sections, but a small enhancement in the cross section was observed at 490 MeV/ c corresponding to the S meson mass in the topological, and π + π − π 0 and π + π + π − π − π 0 cross sections. If the extensive of the S meson with a mass and width of 1935.5 and 2.8 MeV/ c 2 is assumed, our measurement gives a total resonant annihilation cross section into charged particles of 10.0±3.0 mb.

8 data tables

FIRST CROSS SECTION IS CHARGED ANNIHILATION CROSS SECTION AND IS THE SUM OF THE 2, 4, AND 6PRONG.

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Two meson final states in interactions of 2.7 GeV/c p p

Domingo, V. ; Fisher, G.P. ; Marshall Libby, L. ; et al.
Phys.Lett.B 25 (1967) 486-488, 1967.
Inspire Record 1389628 DOI 10.17182/hepdata.29436

The cross sections for π + π − , K + K − , and K 0 K 0 final states from 2.7 GeV/ c p p interactions are: 28±9 γ b, 3 +6 −3 γb, and < 10 γb respectively. Angular distributions are presented and discussed.

1 data table

Axis error includes +- 0.0/0.0 contribution (?////Due to contamination by other final states).