We present results on a high statistics study of the proton structure functions F 2 ( x , Q 2 ) and R = σ L / σ T measured in deep inelastic scattering of muons on a hydrogen target. The analysis is based on 1.8 × 10 6 events after all cuts, recorded at beam energies of 100, 120, 200 and 280 GeV and covering a kinematic range 0.06 ⩽ x ⩽ 0.80 and 7 GeV 2 ⩽ Q 2 ⩽260 GeV 2 . At small x , we find R to be different from zero in agreement with predictions of perturbative QCD.
THE AVERAGE VALUES OF Q**2 AT EACH OF THE X VALUES LISTED IN THIS TABLE ARE 15,20,20,25,30,35,40,45,50,50.
R=SIG(L)/SIG(T) IS TAKEN TO BE ZERO.
R=SIG(L)/SIG(T) IS TAKEN TO BE ZERO.
A search for baryonia with negative and positive strangeness decaying respectively into\(\Lambda+ \bar p + pions\) and\(\bar \Lambda+ p + pions\) has been carried out in a neutron beam with a mean momentum of ≅40 GeV/c in an experiment performed at the Serpukhov accelerator. There is a strong indication of the existence of these baryonia. The following four charge states are observed for negative and positive strangeness: neutral, negative, positive and doubly charged. Their mean mass is 3055±25 MeV/c2 and the width Γ≦36±15 MeV/c2. The data show that the isotopic spin of the baryonia is ≧3/2. The baryonia production cross sections in the acceptable kinematic regionXF≧0.2 andPT≦1 GeV/c times the branching ratios of the observed decays are of the order of 1 μb per nucleon.
No description provided.
The production of neutral pions by the interaction of 200A·GeV p and16O projectiles with a Au target has been studied in the pseudorapidity range 1.5≦η≦2.1. Transverse momentum spectra have been measured between 0.4 GeV/c and 3.6 GeV/c and their dependence on the centrality of the collision has been investigated. The peripheral-collision spectra display a marked change of slope with a hard component starting at about 1.8 GeV/c, in contrast to central-collision data. The data are discussed in comparison to p+p and α+α data from the ISR.
Data obtained with minimum bias trigger conditions.
Data obtained with minimum bias trigger conditions.
Data for central collisions.
We have measured the inclusive production of γ, π0 and η ine+e− annihilation at the center of mass energy of 35 GeV. The differential cross sections, extended to the kinematical limit and measured with high accuracy, are found to be in good agreement with previously reported results. Using the measured spectra we determine the average multiplicity for each of these particle species.
No description provided.
Statistical errors only.
Statistical errors only.
The production of neutral strange particlesKso, Λ and\(\bar \Lambda \) has been studied in 60 and 200 GeV per nucleon OAu and pAu collisions with the streamer chamber vertex spectrometer of the NA35 experiment at the CERN-SPS accelerator. Ratios of neutral strange particle production to negatively charged particle production in selected regions of phase space were measured to be the same in OAu and pAu reactions. The rates of strange particle production in central OAu collisions are about a factor of 16 higher than in pAu collisions when compared in the same regions of phase space. If an enhancement of strange particle production in OAu collisions relative to pAu collisions is considered to be a signature for quark-gluon plasma formation, no evidence supporting it is observed. The experimental results are compared to the Lund FRITIOF model.
No description provided.
No description provided.
No description provided.
None
206 EVENTS.
206 EVENTS.
4000 EVENTS.
We present results on the photoproduction of 10 000 charmed particles from the 108 recorded triggers of Fermilab experiment E691. The total cross section for the photoproduction of D0 and D+ particles (and antiparticles) for xF>0.2 is measured to be 3.88±0.06±0.40 μb/Be nucleus at 〈Eγ〉=145 GeV. We have also measured the relative production of different charmed particles, their pT2 and xF distributions, and the energy dependence of the total charm cross section. The mean pT2 is 1.16±0.04 GeV2/c2 and the ratio of charm cross sections at 200 and 100 GeV is 1.96±0.24. Results of fits to the xF distribution are also reported.
D0/AD0 cross section from K-PI+/K+PI- decay mode.
D+/D- cross section from K-2PI+/K+2PI- decay mode.
D*+/D*- cross section from D0<K-PI+>PI+ + CC decay mode.
The transverse-momentum spectra of lambdas (Λ0, Λ¯0) produced in the central region has been measured in p¯p collisions at s=1.8 TeV at the Fermilab Collider. We find that the average transverse momentum of the lambdas increases more rapidly with center-of-mass energy than that of charged particles, and the ratio of lambdas to charged particles increases as a function of center-of-mass energy.
No description provided.
No description provided.
No description provided.
We report new measurements of the production cross section for the reaction e+e−→τ+τ− at s=29 GeV, as well as the topological decay branching fractions of the τ lepton. The data were taken with the High Resolution Spectrometer at the SLAC e+e− colliding-beam facility PEP. The measured cross section yields Rττ=1.044±0.014±0.030 [where the first (second) error is statistical (systematic)], consistent with QED and corresponding to QED cutoff parameters of Λ+>129 GeV and Λ−>284 GeV at the 95% C.L. The fractions of τ decays into one and three charged particles are B1=0.864±0.003±0.003 and B3=0.135±0.003±0.003.
No description provided.
Inclusive jet production at s=1.8 TeV has been measured in the CDF detector at the Fermilab Tevatron p¯p Collider. Jets with transverse energies (Et) up to 250 GeV have been observed. The Et dependence of the inclusive jet cross section is consistent with leading-order quantum-chromodynamic calculations, and comparison with lower-energy data shows deviations from scaling consistent with QCD. A lower limit of 700 GeV (95% confidence level) is placed on the quark compositeness scale parameter Λc associated with an effective contact interaction.
No description provided.
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