The reaction K − n → K − π + π − n has been studied in the SLAC 82″ liquid deuterium bubble chamber with a beam momentum of 12 GeV/ c . Although the kinematic fit for this final state has only one constraint, nonetheless a reasonably pure sample has been obtained. The cross section for the reaction is 1.02 ± 0.10 mb. The process K − n → K ∗0 890 Δ − is observed with cross section 36 ± 9 μ b and t -slope of 10 ± 2 (GeV/ c ) −2 . A kaon diffraction dissociation sample has been obtained, although the Q-signal is not so strong as in experiments with proton targets. Neutron dissociation into n π + π − is also observed with similar properties to those of proton dissociation into p π + π − , but with a broader t -distribution.
We have measured differential cross sections for K−p→Σ+π− and π−p→pπ− at 3.0 and 5.1 GeV/c near the backward direction. At 3.0 GeV/c both have a dip near −u∼0.1 (GeV/c)2. At 5.1 GeV/c, dσdu for π−p→pπ− falls exponentially with slope 3.8±0.1 (GeV/c)−2 whereas dudσ for K−p→Σ+π− exhibits a decreasing slope for larger |u|. These data are discussed in terms of SU(3), and the relative importance of the helicity-flip and -non-flip amplitudes is investigated.
This Letter reports measurements of the ratios of $\pi$, K, and p production at large values of transverse momentum in $\pi^- −p$ collisions. The charge ratios, such as $\frac {\pi^−} {\pi^+}$, $\frac {K^−} {K^+}$, and $\frac {\overline{p}}{p}$ are seen to be quite different from those measured in p −p collisions. These ratios are sensitive tests of hard-scattering models, and are compared with theoretical predictions. The particle ratios have also been studied as a function of center-of-mass angle ($\theta^*$) at $\theta^*$ = 90°, 77°, and 60°.
We present results for the differential cross sections of neutrinos and antineutrinos on nucleons in the energy range E = 2−200 GeV, from the BEBC and Gargamelle experiments. The structure functions F 2 , 2 χF 1 and χF 3 have been evaluated as a function of χ and q 2 . Deviations are observed from Bjorken scaling, which are very similar to those found in electron and muon inelastic scattering. For the Callan-Gross ratio, we find 2χF 1 F 2 = 0.80 ± 0.12 and the corresponding value for 〈R〉 = 〈 σ S σ T 〉 = 0.15 ± 0.10 . Our results are consistent with the Gross-Llewellyn-Smith sum rule; we measure ⩾2.5 ± 0.5 valence quarks per nucleon. Quark and antiquark distributions are given. The Nachtmann moments of F 2 and χF 3 are quantitatively consistent with the predictions from QCD. The value of the strong interaction parameter is λ = 0.74 ± 0.05 GeV without corrections, and 0.66 ± 0.05 GeV including α S 2 corrections. The moments of the gluon distribution are found to be positive and indicate an χ distribution of gluons which is comparable with that of the valence quarks.
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We have measured, as a function of transverse momentum (p⊥), the invariant cross section Edσd3p for the production of π±, K±, p, p¯, d, and d¯ in proton collisions with a tungsten (W) target at incident proton energies of 200, 300, and 400 GeV. The measurements were made in the region of 90° in the c.m. system of the incident proton and a single nucleon at rest. Measurements were also made with 300-GeV protons incident on Be, Ti, and W targets of equal interaction length. These p-nucleus measurements, which show a strong dependence on atomic number at high p⊥, were used to extract effective proton-nucleon cross sections by extrapolation to atomic number unity. At large values of the scaling variable x⊥=2p⊥s, where s is the square of the c.m. energy, the pion data are found to be well represented by the expression (s)−ne−ax⊥, with n=11.0±0.4 and a=36.0±0.4. x⊥<0.35, where similar measurements have been made at the CERN ISR, our data are in good agreement with the ISR data.
The differential cross section for neutron-deuteron elastic scattering was measured for four-momentum transfers 0.3 < − t < 2.0 (GeV/c) 2 with incident neutron momenta between 6 and 12.5 GeV/c. The measurement was made with spark chambers at the Argonne ZGS. Results are compared with proton-deuteron elastic scattering at comparable energies as a test of isospin invariance in strong interactions and with the predictions of the Glauber multiple scattering theory. Very good agreement is found.
We have measured the inclusive production of massive dimuons (7<~Mμμ<~11 GeV/c2) by 200-, 300-, and 400-GeV protons incident on Cu in order to check whether the dimensionless cross section Mμμ3[dσdMμμdy]y=0 is a function of Mμμ2s alone, where s is the square of the c.m. energy. The results support the scaling hypothesis.
We have observed muon pairs with effective masses in the range 7<~Mμμ<~11 GeV/c2 produced by 300- and 400-GeV protons incident on a Cu target at Fermilab. The production cross section per nucleon, dσdMμμ, for 400-GeV incident protons is found to fall from 1 × 10−36 cm2/(GeV/c2) at Mμμ=7.7 GeV/c2 to 2.7 × 10−38 cm2/(GeV/c2) at Mμμ=11.2 GeV/c2. We find that a significant fraction of the observed direct single muons come from high-mass dimuons.
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