Final states π − Σ + , π + Σ − , π o Λ and ηΛ were studied for K − p reactions at 3.95 GeV/ c . Cross sections, angular distributions and polarizations are presented. Data for π − Σ + and π o Λ production are compared to the line-reversed πp reactions at the same beam momentum. Baryon-exchange peaks are presented for the Σ + π − , Σ − π + and Λπ o final states.
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We present results on three reactions involving neutral final states which were studied in a magnet spark chamber system. These results are: (a) differential cross section with high statistics for K − p → K 0 n at 5 GeV /c (24 000 events) and at 8 GeV/ c (11 000 events) for t′ <2.0 (GeV/ c ) 2 ; (b) differential cross section and polarization for K − p → Λπ 0 (backward peak) at 5 GeV/ c for u ′ < 1.4 GeV/ c ) 2 ; and (c) differential cross section for K − p → K 0 Δ 0 (1232) at 5 GeV /c for t′ < 1.2 ( GeV /c) 2 . We compare our results with existing data and draw some phenomenological conclusions.
Axis error includes +- 0.0/0.0 contribution (?////TP INDEPENDENT CORRECTIONS AT 5 AND 8 GEV ARE 5.143 +- 0.418 AND 4.981 +- 0.436 RESPECTIVELY).
Axis error includes +- 0.0/0.0 contribution (?////TP INDEPENDENT CORRECTIONS AT 5 AND 8 GEV ARE 5.143 +- 0.418 AND 4.981 +- 0.436 RESPECTIVELY).
Axis error includes +- 0.0/0.0 contribution (?////UP INDEPENDENT CORRECTION FACTOR IS 3.840 +- 0.323).
Differential cross sections and polarizations are presented for the reactions K − p → Λπ 0 , Λη , Λη ′ at 8.25 GeV/ c incident K − momentum. The data, which come from a high statistics experiment in the CERN 2 m bubble chamber, are compared with previous experimental results on the same reactions and with current theoretical ideas.
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We have investigated the ρ-meson production mechanism in the three reactions π±p→ρ±p and π−p→ρ0n at 3.9 GeV/c (s=8.2 GeV2) using the prism-plot technique. Differential cross sections at all momentum transfers are presented. A significant backward peak has been found in all three reactions. The differential cross sections for these backward peaks are given and are compared with the equivalent pion elastic and charge-exchange cross sections in the backward direction. Using a linear combination of the three differential cross sections we have isolated the I=0 exchange contribution in the forward direction. This differential cross section has a zero at −t=0.45 (GeV/c)2 and is fitted by the dual absorptive model of Harari with an interaction radius of ∼ 1.2 F. The total I=0 cross section is calculated and compared with similarly determined cross sections at higher momenta. An analysis of the properties of the other possible spin-parity exchanges is also presented.
SLOPE FITTED OVER 0.05 < -T < 0.3 GEV**2.
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The annihilation\(\bar pn\) → π−π0 has been studied in a D2 bubble chamber at several beam momenta between 1.0 and 1.6 GeV/c. The cross-section has been measured to be (110±15) μb at an average beam momentum of 1.3 GeV/c. The study of the angular distribution shows the presence of anL = 3 wave.
NO CORRECTIONS APPLIED FOR SPECTATOR PROTON MOMENTUM CUT NOR FOR ANY RESCATTERING IN DEUTERIUM NUCLEI.
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DIP AT -U = 0.4 TO 0.6 (REFLECTING DIP NEAR COS(THETA) = -0.8).
The reactions π − p → p π − and π − p → p ϱ − ( ϱ − → π − π 0 ) at 10 GeV/ c with the proton in the forward direction in the c.m.s. are discussed on the basis of 953 elastic scattering events and 2240 events of the reaction π − p → p π − π 0 . The total backward cross sections are 0.52±0.10 and 1.52±0.28 μ b, respectively. In both cases the production mechanism is compatible with the dominance of the baryonic Δ δ Regge trajectory exchange. The ϱ − decay angular distributions are studied in the u -channel helicity frame and the spin density matrix elements are presented as functions of u .
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DATA FROM PRIV COMM WITH B. GHIDINI.
DATA FROM PRIV COMM WITH B. GHIDINI.
Data on the reactions π − p → p π − , p p → π + π − , K − p → pK and p p → p p at 8 and 12 GeV/ c are presented. Our results agree with line reversal symmetry (between π − p → p π − and p p → π + π − ), Regge pole behaviour for non-exotic reactions ( π − p → p π − , p p → π + π − ), and universal behaviour for exotic reactions ( p p → p p , K − p → pK − ) with d σ /d u | u =0 ∼ s −10 excluding the existence of a “glory” mechanism in p p elastic backward scattering in our energy range.
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We have studied backward meson and baryon production in π−p→nπ+π− at 8 GeV/c using a streamer chamber triggered by the detection of the interaction of the neutron in thick-plate optical spark chambers. Our data sample of 866 events is dominated by the quasi-two-body final states Δ−(1232)π+, nρ0, and nf0. We study the differential and total backward cross sections for these states and the decay angular distributions of the resonances. The results for the Δ− and ρ0 indicate that both nucleon and Δ exchange in the u channel are important in their production, while f0 production is, as expected, consistent with nucleon exchange.
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BACKWARD DIP.
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Backward production of ϱ 0 and f 0 mesons in π + n interactions at 6 GeV/ c is presented. Total and differential cross sections are reported along with spin density matrix elements.
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JACKSON (U) FRAME (Z=2).
Final states produced by charged baryon exchange in π − p interactions at 12 GeV/ c laboratory momentum have been studied. Forward neutrons with momenta determined by a calorimeter to be greater than 8.5 ± 1.4 GeV/ c triggered the SLAC 40-inch hydrogen bubble chamber which operated at a 10 Hz expansion rate. We report data on the reactions π − p→n π − π + , π − p→n π − π + π 0 , and π − p→n π − π − π + π + . In π − n π − p→n π + , production of ϱ and f mesons is observed. Differential cross sections are derived and compared with data at lower incident momentum and with theoretical models. In π − p→n π − π + π 0 , ω production is observed with a differential cross section having a deep near u ′= 0.2 (GeV/ c ) 2 . In π − p→n π − π − π + π + , Δ − , ϱ and f production is observed . The observed mass distributions appear to indicate the production of wide resonaces decaying into ϱππ. Some evidence for ϱ-ω interference is also observed.
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CORRECTED FOR BACKGROUND.