From measurements of proton-proton elastic scattering at very small momentum transfers where the nuclear and Coulomb amplitudes interfere, we have deduced values of ρ, the ratio of the real to the imaginary forward nuclear amplitude, for energies from 50 to 400 GeV. We find that ρ increases from -0.157 ± 0.012 at 51.5 GeV to +0.039 ± 0.012 at 393 GeV, crossing zero at 280 ± 60 GeV.
From analysis of V0 events observed in an exposure of the National Accelerator Laboratory 30-in. bubble chamber to 303−GeVc protons, we obtain these results: (1) 〈nπ0〉 rises approximately linearly with n-, implying strong coupling of neutral and charged pions, while 〈nKS0〉 is less coupled to n; (2) γ, KS0, and Λ0 production cross sections are approaching a scaling limit by 303 GeVc; (3) within the limited statistics, dσdy is flat in the central region for KS0 and low-multiplicity γ events.
In an exposure of the 30-in. hydrogen bubble chamber to a 303−GeVc proton beam, 2245 interactions have been observed. The measured total cross section is 39.0±1.0 mb and the average charged particle multiplicity 〈nch〉=8.86±0.16.
In a 35 000-picture exposure of the Fermilab 30-in. hydrogen bubble chamber to a 300-GeV/c proton beam 1863 neutral V0's were measured. The inclusive cross sections for γ, Ks0, Λ0Σ0, and Λ¯0Σ¯0 are 257 ± 18 mb, 7.3 ± 0.6 mb, 3.6 ± 0.4 mb, and 1.0 ± 0.3 mb, respectively. The correlation with charged particles and other inclusive features are studied.
In a 35 000-picture exposure of the 30-in. hydrogen bubble chamber to a 300-GeV/c proton beam at the Fermi National Accelerator Laboratory, 10054 interactions have been observed. The measured total cross section is $40.68 \pm 0.55$ mb, the elastic cross section is $7.89 \pm 0.52$ mb, and the average charged-particle multiplicity for inelastic events is $8.S0 \pm 0.12$.
The slope b(s) of the forward diffraction peak of p−p elastic scattering has been measured in the momentum-transfer-squared range 0.005≲|t|≲0.09 (GeV/c)2 and at incident proton energies from 8 to 400 GeV. We find that b(s) increases with s, and in the interval 100≲s≲750 (GeV)2 it can be fitted by the form b(s)=b0+2α′lns with b0=8.23±0.27, α′=0.278±0.024 (GeV/c)−2.
Data on inclusive jet production in the transverse-momentum (p⊥) range 0-8 GeV/c for 200-GeV/c p, π−, π+, K−, K+, and p¯ incident on a hydrogen target are presented. The jet cross section is fully corrected for losses and biases, and compared with the predictions of a model based on quantum chromodynamics. Both the absolute cross section and the inclusive charged-particle distributions inside and outside the jet are in qualitative agreement with the model.
We report the first observation of diffractively produced open charm in 800−GeV/c pp collisions of the type pp→pD*X. We measure cross sections of σdiff(D*+)=(0.185±0.044±0.054)μb and σdiff(D*−)=(0.174±0.034±0.029)μb. Our measurements are based on 4.3×109 events recorded by FNAL E690 in the fixed-target run of 1991. We compare our results with previous fixed-target charm experiments.
Proton-proton and proton-deuteron elastic scattering has been measured for incident laboratory energy from 50 to 400 GeV; minimum |t| values were, for p−p, 0.0005 (GeV/c)2, and for p−d, 0.0008 (GeV/c)2. From the differential cross sections we have determined the ratios of the real to imaginary parts of the forward scattering amplitude, ρpp and ρpd, for p−p and p−d scattering. Using a Glauber approach and a sum-of-exponentials form factor we obtain ρpn for p−n scattering.
We have measured the differential cross section for small angle p−p scattering from 25 to 200 GeV incident energy and in the momentum transfer range 0.015<|t|<0.080 (GeVc)2. We find that the slope of the forward diffraction peak, b(s), increases with energy and can be fitted by the form b(s)=b0+2α′ lns, where b0=8.3±1.3 and α′=0.28±0.13 (GeVc)−2. Such dependence is compatible with the data existing both at higher and lower energies. We have also obtained the energy dependence of the p−p total cross section in the energy range from 48 to 196 GeV. Within our errors which are ± 1.1 mb the total cross section remains constant.