We report on a measurement for the branching-ratio X 0 → 2γ X 0 ar all. Our result is X 0 → 2γ X 0 → all = (2.9 ± 0.9)% .
BY COMPARISON WITH THE KNOWN ETA PRODUCTION CROSS SECTION.
From a 3.5 ev/μb exposure of the BNL 80 inch chamber filled with deuterium to a 7.0 GeV/ c p beam we obtained 664 events in the channel p n → p π − p . The channel cross section is (1270 ± 110 60 ) μb. The final state is dominated by Δ (1230) production. The experimental data is well described by a one-pion exchange model with off-mass shell corrections.
No description provided.
As a partial result of an analysis of K + d interactions at 3 GeV/ c produced in the 81 cm Saclay bubble chamber, we present data on K + differential cross sections for the following reactions: K + d → K + d, K + d → K + pn, K + d → K 0 pp . A set of parameters describing the K + n elastic scattering has been obtained from a simulataneous fit, based on the Glauber model. to the three experimental differential cross sections and to the K + d total cross section, giving α n = 1.7 ± 0.5 GeV −2 for the slope α n of the differential cross section, and ρ n = −0.16 ± 0.3 for the ratio of the real to the imaginary part of the forward scattering amplitude. The D-wave function of the deuteron has been found to give a non-negligible contribution to the coherent reaction.
No description provided.
No description provided.
No description provided.
The reaction π − p → ηφ has been studied at 1.8 GeV/ c incident pion momentum using the Bologna-CERN NBC set-up, in order to investigate the electromagnetic decay mode φ → ηγ . We observed (27 ± 6) events, yielding a branching ratio Γ(φ → ηγ) Γ(φ → total ) = (7.3 ± 1.9)% . The theoretical implications of this result are discussed.
ASSUMING THE TOTAL PHI CROSS SECTION IS 35 +- 5 MUB, THIS YIELDS THE BRANCHING RATIO OF (7.3 +- 1.9) PCT FOR PHI --> ETA GAMMA.
For the reaction γ p → K + Λ 0 the differential cross section has been measured at t = −0.147 GeV 2 ( θ C.M. = 26.5 ± 3.5°) and photoenergies between 1.05 and 2.2 GeV and for the reaction γ p→K + Σ 0 at ≈−0.17 GeV 2 ( θ C.M. = 28±3.5°) and photoenergies between 1.3 and 2.2 GeV. For this four momentum transfer the differential cross section of K + Λ 0 photoproduction has a surprising steep increase above threshold and stays nearly constant up to 2.2 GeV. The K + Σ 0 cross section increases from 1.3 to 1.56 GeV and goes down gradually at higher energies.
AT CONSTANT MOMENTUM TRANSFER OF -T = 0.147 GEV**2.
AT APPROXIMATELY CONSTANT MOMENTUM TRANSFER OF -T = 0.17 GEV**2.
Lambda production is studied in K − p interactions at 10.1 GeV/ c , where the dominant reaction is K − p → Λ + pions. General characteristics such as the distributions of the double differential cross section in the lab system, of the variable x = p L ∗ p max ∗ , of p ⊥ 2 and of the missing mass to the lambda are presented. Total cross sections for Λ production and for the various channels are given. Differential cross sections d σ d t , d σ d t′ and d σ d u′ are presented. Forward and backward peaks are observed in the d σ d t′ and d σ d u′ distributions, respectively. It is found that the exponential slope of these distributions decreases with increasing missing mass to the lambda and, for d σ d t′ , also for increasing multiplicity in the final state. The polarization of the lambdas is studied as a function of multiplicity, p L ∗ , (Λπ ± ) effective mass, t ′ and u ′. The forward lambdas show
No description provided.
POSSIBLE FORWARD DIP.
We present results on the differential cross sections for the process K + n → K 0 p extracted from the reaction K + d → K 0 pp measured at 13 momenta between 0.64 and 1.51 GeV/ c .
THESE TOTAL CROSS SECTIONS WERE PRESENTED WITH MORE EXPERIMENTAL DETAILS IN G. GIACOMELLI ET AL., NP B37, 577 (1972).
REACTION HAS A SPECTATOR PROTON. THESE ARE NOT FREE NEUTRON CROSS SECTIONS. A 250 MEV/C MOMENTUM CUT IS APPLIED TO THE SPECTATOR MOMENTUM AND D(SIG)/DOMEGA THEN NORMALIZED TO THE UNCUT TOTAL CROSS SECTION FOR K+ DEUT --> K0 P P.
The Λ polarization in the reaction γp → K + Λ has been measured using the decay Λ → pπ − as an analyzer. It is found to be large and negative in the momentum transer range 0.2 ⩽ | t | ⩽ 1.0 (GeV/ c ) 2 .
No description provided.
The Λp, Λn, Λ p, and Λ n total cross-sections were measured in the Λ momentum interval 6–21 GeV/ c . Within the experimental uncertainties the cross-sections are momentum-independent in this interval and the momentum-averaged cross-sections are found to be: σ ( Λp ) = 34.6 ± 0.4 mb : σ ( Λn ) = 34.0 ± 0.8 mb ; σ ( Λp ) = 56 ± 11 mb ; σ ( Λn ) = 46 ± 20 mb . The first two results are in agreement with charge symmetry, and with simple quark model sum rules applied to previous results on pp, K - n, and π + p total cross-sections.
NO SIGNIFICANT MOMENTUM DEPENDENCE OVER THIS INTERVAL. 2.8 +- 0.3 MB SHADOWING CORRECTION APPLIED FOR NEUTRON CROSS SECTION.
6 MB SHADOWING CORRECTION APPLIED FOR NEUTRON CROSS SECTION.
The elastic scattering of K ± mesons on protons has been studied at 5 GeV/c. A total of about 500 000 events have been measured in the c.m. angular range 17° < θ cm < 165° corresponding to 0.2 < − t < (GeV/ c ) 2 . We observed a K − p backward peak which we have parametrized as d σ /d u = (0.6 ± 0.2) exp [(3.3 ± 0.6) u ] μb /(GeV/c) 2 , while for the K + p backward peak we find d σ /d u = (17.5 ± 1) exp [(3.6 ± 0.2) u ] μb /(GeV/c) 2 . The K − p cross-section falls to about 0.03 μ b ( GeV /c) 2 around − t = 5 (GeV/ c ) 2 , while the K + p cross-section stays in the vicinity of 0.3 μ b ( GeV /c) 2 in the same t -region. The K + p and K − p differential cross-sections have cross-over points at − t = 0.2, 1.1 and about 3.5 (GeV/ c ) 2 .
No description provided.
No description provided.
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