PBAR P --> K- K+
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Experimental study study of antiproton-proton annihilation into a pair of charged Pi-Mesons or K-Mesons for incident antiproton mementa in the range from 0.72 GeV/c to 2.62 GeV/c

Fong, Douglas G. ; Pine, Jerome ;
RX-294, 1968.
Inspire Record 53368 DOI 10.17182/hepdata.50355

The cross sections for the two antiproton-proton annihilation-in-flight modes, ˉp + p → π+ + π- ˉp + p → k+ + k- were measured for fifteen laboratory antiproton beam momenta ranging from 0.72 to 2.62 GeV/c. No magnets were used to determine the charges in the final state. As a result, the angular distributions were obtained in the form [dσ/dΩ (ΘC.M.) + dσ/dΩ (π – ΘC.M.)] for 45 ≲ ΘC.M. ≲ 135°. A hodoscope-counter system was used to discriminate against events with final states having more than two particles and antiproton-proton elastic scattering events. One spark chamber was used to record the track of each of the two charged final particles. A total of about 40,000 pictures were taken. The events were analyzed by measuring the laboratory angle of the track in each chamber. The value of the square of the mass of the final particles was calculated for each event assuming the reaction ˉp + p → a pair of particles with equal masses. About 20,000 events were found to be either annihilation into π ±-pair or k ±-pair events. The two different charged meson pair modes were also distinctly separated. The average differential cross section of ˉp + p → π+ + π- varied from ~ 25 µb/sr at antiproton beam momentum 0.72 GeV/c (total energy in center-of-mass system, √s = 2.0 GeV) to ~ 2 µb/sr at beam momentum 2.62 GeV/c (√s = 2.64 GeV). The most striking feature in the angular distribution was a peak at ΘC.M. = 90° (cos ΘC.M. = 0) which increased with √s and reached a maximum at √s ~ 2.1 GeV (beam momentum ~ 1.1 GeV/c). Then it diminished and seemed to disappear completely at √s ~ 2.5 GeV (beam momentum ~ 2.13 GeV/c). A valley in the angular distribution occurred at cos ΘC.M. ≈ 0.4. The differential cross section then increased as cos ΘC.M. approached 1. The average differential cross section for ˉp + p → k+ + k- was about one third of that of the π±-pair mode throughout the energy range of this experiment. At the lower energies, the angular distribution, unlike that of the π±-pair mode, was quite isotropic. However, a peak at ΘC.M. = 90° seemed to develop at √s ~ 2.37 GeV (antiproton beam momentum ~ 1.82 GeV/c). No observable change was seen at that energy in the π±-pair cross section. The possible connection of these features with the observed meson resonances at 2.2 GeV and 2.38 GeV, and its implications, were discussed.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


Determination of the electric and magnetic form-factors of the proton in the timelike region

Bardin, G. ; Burgun, G. ; Calabrese, R. ; et al.
Nucl.Phys.B 411 (1994) 3-32, 1994.
Inspire Record 376134 DOI 10.17182/hepdata.32865

The s dependence of the electromagnetic proton form factors in the time-like region has been determined from the threshold ( s = 4 M p 2 ) up to s = 4.2 GeV 2 . Data were collected in a dedicated experiment performed at the LEAR antiproton ring at CERN, increasing by one order of magnitude the available statistics. Total and differential cross section of the p p → e − e + reaction have been measured. The electric and magnetic form factors are found to have comparable value. The observed form factor shows a clear steep s dependence close to the threshold.

6 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Elastic Scattering of Charged Mesons, Anti-protons and Protons on Protons at Incident Momenta of 20-{GeV}/$c$, 30-{GeV}/$c$ and 50-{GeV}/$c$ in the Momentum Transfer Range $0.5-{\rm GeV}/c^2 < -t < 8-{\rm GeV}/c^2$

The Annecy(LAPP)-CERN-Bohr Inst-Genoa-Oslo-London collaboration Asad, Z. ; Baglin, C. ; Bock, R. ; et al.
Nucl.Phys.B 255 (1985) 273-327, 1985.
Inspire Record 206292 DOI 10.17182/hepdata.33789

Results are presented from experiment WA7 at the CERN SPS, which has measured the elastic differential cross sections of π ± p, K ± p, p p and pp at incident momen ta of 20, 30 and 50 GeV/ c . The measurements cover the momentum transfer range 0.5 < | t | < 8 (GeV/ c ) 2 , corresponding to c.m. scattering angles between 10° and 50°. The experimental set-up, trigger logic and data analysis are described. The experimental results are compared with existing meson-proton and nucleon-proton data at lower and higher energies covering the medium- and large-| t | region. Some prominent models and their predictions for elastic scattering at WA7 energies and beyond are reviewed, with emphasis on geometrical scaling, factorizing eikonal models, lowest-order QCD and other dynamical exchange-type models. Results for p p two-body annihilation into π − π + and K − K + at 30 and 50 GeV/ c , obtained in parallel with the elastic p p data, are also presented.

9 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Proton-antiproton annihilation into pi+ pi- and k+ k- from 700 to 1100 mev/c

Mandelkern, M.A. ; Burns, R.R. ; Condon, P.E. ; et al.
Phys.Rev.D 4 (1971) 2658-2666, 1971.
Inspire Record 74756 DOI 10.17182/hepdata.23118

Total and differential cross sections are presented for proton-antiproton annihilation into π+π− and K+K− at six laboratory momenta between 686 and 1098 MeV/c. The two-pion final state displays moderate energy dependence in its differential cross section, but shows no evidence of any direct-channel resonances. In contrast, the two-kaon final state exhibits some behavior in the total and differential cross section suggestive of a possible direct-channel effect between 800 and 1000 MeV/c.

3 data tables
Table 1

NOTE CUT EXCLUDES LARGE FORWARD CROSS SECTION.

Table 2

LEGENDRE COEFFICIENTS NORMALIZED TO LEGN(L=0) = 0.5.

Table 3

LEGENDRE COEFFICIENTS NORMALIZED TO LEGN(L=0) = 0.5.


Measurement of the anti-Proton-Proton Annihilation Cross-Section Into pi+ pi- Or K+ K- at 300-MeV/c

Bassompierre, G. ; Schneegans, M.A. ; Binder, G. ; et al.
Lett.Nuovo Cim. 20 (1977) 29-33, 1977.
Inspire Record 125074 DOI 10.17182/hepdata.37409

None

1 data table
Table 1

ANNIHILATION INTO CHARGED PION OR KAON PAIRS. THE SEPARATE CROSS SECTIONS FOR PIONS AND KAONS ARE CALCULATED ASSUMING SIG(K+K-)/SIG(PI+PI-) IS 0.33 +- 0.05 FROM INTERPOLATION OF OTHER EXPERIMENTS.


Comparison of new data on anti-p p --> pi- pi+ and other two meson states at 2.3-gev/c

Fields, T. ; Cooper, W.A. ; Rhines, D.S. ; et al.
Phys.Lett.B 40 (1972) 503-506, 1972.
Inspire Record 75681 DOI 10.17182/hepdata.28267

Complete angular distributions for the reactions p p → π − π + and other two meson states at 2.3 GeV/ c are presented. The extraordinary π − π + angular distribution is contrasted with the other final states and the predictions of simple models. A favourable comparison is made with the qualitative features of a dual model involving high mass meson states with a strong degeneracy with respect to I -spin.

2 data tables
Table 1

SOME ANGULAR DISTRIBUTIONS ALSO PRESENTED.

Table 2

K* NEUTRAL TO CHARGED PRODUCTION RATIO.


A measurement of anti-p p ---> pi+ pi- and anti-p p ---> k- k+ for small values of t and u at 3 and 4 gev/c

Brabson, A. ; Calvelli, G. ; Cittolin, S. ; et al.
Phys.Lett.B 42 (1972) 287-290, 1972.
Inspire Record 85008 DOI 10.17182/hepdata.28189

We have measured with good statistics the differential cross section for p p →π + π − , K + K − around 0°. Our data and previous results show that the s -dependence of dσ/d t has a value compatible with the appropriate baryon exchange.

6 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Differential cross-sections for anti-p p ---> pi- pi+, k- k+ between 0.8 and 2.4 gev/c

Eisenhandler, E. ; Gibson, W.R. ; Hojvat, C. ; et al.
Phys.Lett.B 47 (1973) 531-535, 1973.
Inspire Record 95394 DOI 10.17182/hepdata.28034

We present measurements from a spark chamber experiment of the differential cross-sections for p p → π − π + , K − K + at 20 momenta in the range 0.8–2.4 GeV/ c (c.m. energy 2.02 to 2.57 GeV). The c.m. angular range was −0.95 < cos θ ∗ < 0.95 . There are about 2000π − π + events and about 300 K − K + events at each momentum.

1 data table
Table 1

ALL ANGLES.


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.


Anti-p p annihilation into pi+ pi- and k+ k- at 5 gev/c

Chabaud, V. ; Eide, A. ; Lehmann, P. ; et al.
Phys.Lett.B 41 (1972) 209-212, 1972.
Inspire Record 75628 DOI 10.17182/hepdata.5626

The differential cross-sections for the annihilation processes p p→π − π + and p p→K − K + have been measured at an incident laboratory momentum at 5 GeV/ c . Strong backward and forward peaks are observed in the π + π − differential cross-sections while the K + K − cross-section is shown to have a peak only for K − going forward. The annihilation cross-sections are compared with the cross-sections for the crossed channel backward processes π ± p→p π ± and K ± p→pK ± .

2 data tables
Table 1

No description provided.

Table 2

No description provided.