We report the results of the investigation of 18 500 frames of π+p interactions in the Brookhaven 20-in. bubble chamber at an incident energy of 900 MeV. It is found that single-pion production proceeds almost entirely through formation of the N33* isobar. The production mechanism of the N33* is analyzed in terms of its spin density matrix. Comparison is made with Stodolsky and Sakurai's ρ-exchange model and with the absorptive peripheral model.
No description provided.
We present data on dimuon production by 16 GeV π + and π − beams on a Cu target. From the data we evaluate, for π − N collisions, the fraction of dimuon events that originate from the annihilation process q q ̄ → μ + μ − . Using this information the experimentally determined cross section for the process q q ̄ → μ + μ − is observed to be in agreement with the Drell-Yan model over a wide range of incident energies. The observed deviations from exact scaling are of the order predicted by QCD calculations for the Q 2 -dependence of the nucleon and the pion structure function.
CROSS SECTIONS ARE PER COPPER NUCLEUS.
CROSS SECTIONS ARE PER COPPER NUCLEUS.
Approximately 60 000 events have been collected in a spark chamber experiment at the CERN Proton Synchrotron which studied elastic diffraction scattering of π--p and p-p at incident momenta of 8.5, 12.4 and 18.4 GeV/c and of π+-p at 8.5 and 12.4 GeV/c. Magnetic analysis of the incoming and diffraction scattered particle, together with measurement of all angles, permitted each event to be determined as elastic subject to three constraints, so that the inelastic background was rejected with. high efficiency, even at the larger momentum, transfers. Much of the data have been processed by the CERN Automatic Flying-Spot DigitizerHPD. A detailed description of the experimental technique and of the methods of analysis is given. The results, together with data from lower energies, confirm the remarkable energy-independence of the shape of the pion-proton diffraction scattering peak up to |t| = 1.5 (GeV/c)2, wheret is the square of the four-momentum transfer, over a range of pion energies from 2 to 18 GeV. Proton-proton scattering does however appear to show a shrinking diffraction peak. In general, the data agree with other experiments using both counter and bubble chamber techniques, but some differences do appear. During the experiment, data were taken which set an upper limit of 2·102 μb/(GeV/c)2 on the differential elastic cross-section dσ/dt over a range of |t| from 20.9 to 23.4 (GeV/c)2 at 13.4 GeV/c incident pion momentum.
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We have measured p−d inelastic scattering at small momentum transfer by detecting the slow-recoil deuterons from a deuterium-gas-jet target. The coherent diffraction dissociation of protons on deuterons was studied in the region 0.03<|t|<0.07 (GeV/c)2, 1.4<MX2<4 GeV2, and for energies from 50 to 275 GeV. In this region, the diffractive cross section exhibits structure and is dominated by an enhancement at MX2∼1.9 GeV2.
No description provided.
No description provided.
No description provided.
We report results from a measurement of the inclusive process p+d→X+d in the region 0.03<|t|<0.12 (GeV/c)2 and 5 GeV2<MX2≲0.11plab for incident proton momenta from 150 to 400 GeV/c. We find that in this region, the differential cross section d2σdtdMX2 varies only slowly with energy, falls exponentially with |t|, and behaves to a good approximation as 1MX2. The measurement was performed at Fermilab by detecting slow-recoil deuterons from a deuterium-gas-jet target placed at the internal beam of the accelerator.
No description provided.
No description provided.
No description provided.
The Fermilab 15-ft bubble chamber, filled with a heavy neon-hydrogen mix, was exposed to a narrow-band νμ beam. Based on the observation of 830 charged-current νμ interactions, the cross section was found consistent with a linear rise with the neutrino energy in the interval 10 GeV<~Eν≲240 GeV. The average slope was determined to be σνEν=(0.62±0.05)×10−38 cm2 GeV−1.
Measured charged current total cross section.
No description provided.
In a sample of B mesons from the decay of the ϒ(4S) produced in e+e− collisions at the Cornell Electron Storage Ring, inclusive protons, antiprotons, lambdas, and antilambdas have been observed. Lower limits to the B-to-baryon branching ratios are derived.
NUMERICAL VALUES OF DATA SUPPLIED BY E.H. THORNDIKE. CORRECTED ANTI(PROTON) PRODUCTION FROM UPSI(4S) DECAY.
NUMERICAL VALUES OF DATA SUPPLIED BY E.H. THORNDIKE. CORRECTED ANTI(LAMBDA) PRODUCTION FROM UPSI(4S) DECAY.
We report on an improved measurement of the value of the strong coupling constant σ s at the Z 0 peak, using the asymmetry of the energy-energy correlation function. The analysis, based on second-order perturbation theory and a data sample of about 145000 multihadronic Z 0 decays, yields α s ( M z 0 = 0.118±0.001(stat.)±0.003(exp.syst.) −0.004 +0.0009 (theor. syst.), where the theoretical systematic error accounts for uncertainties due to hadronization, the choice of the renormalization scale and unknown higher-order terms. We adjust the parameters of a second-order matrix element Monte Carlo followed by string hadronization to best describe the energy correlation and other hadronic Z 0 decay data. The α s result obtained from this second-order Monte Carlo is found to be unreliable if values of the renormalization scale smaller than about 0.15 E cm are used in the generator.
Value of LAMBDA(MSBAR) and ALPHA_S.. The first systematic error is experimental, the second is from theory.
The EEC and its asymmetry at the hadron level, unfolded for initial-state radiation and for detector acceptance and resolution. Errors include full statistical and systematic uncertainties.
New data is presented on the ratios of structure functions F 2 ( x , Q 2 ) measured in deep inelastic muon scattering with deuterium, nitrogen, and iron targets. The existence of nuclear effects at large Q 2 is confirmed with improved systematic accuracy. The ratio F 2 Fe ( x ) F 2 D 2 ( x ) covers the range 0.20 ⩽ x ⩽ 0.70 and is in agreement with earlier measurements. The ratio F 2 N 2 ( x )/ F 2 D 2 ( x ) is measured over the range 0.08 ⩽ x ⩽ 0.70 and is compatible with unity below x = 0.3.
VALUES OF Q2 CORRESPONDING TO THE X-BINS IN THIS TABLE ARE:- 46-106,46-106,53-150,53-200,70-200,80-200 RESPECTIVELY.
VALUES OF Q2 CORRESPONDING TO THE X-BINS IN THIS TABLE ARE:- 26-40,26-61,30-80,30-106,30-106,30-150,30-200,35-200,46-200.
The inclusive cross sections for π − , π 0 , π + and η production in K − p interactions at 14.3 GeV/ c are calculated. The invariant cross section distributions are presented and compared in the whole phase space for π + and π 0 , and in the backward c.m. region for π − . In the fragmentation regions, the charged pion production is analysed in terms of the triple-Regge model.
No description provided.
No description provided.
No description provided.
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