K+p and K+d total cross sections were measured in the momentum range 0.57-1.16 GeV/c using a secondary, separated kaon beam of the Lawrence Berkeley Laboratory Bevatron and conventional transmission-counter techniques. No evidence was found for structure in the cross section of either reaction as previously indicated near 0.7 GeV/c.
No description provided.
The total cross sections σT of p, p¯, π±, and K± on hydrogen and deuterium have been measured between 6 and 22 GeVc at intervals of 2GeVc to an accuracy greater than previously reported. The method utilized was a conventional good-geometry transmission experiment with scintillation counters subtending various solid angles at targets of liquid H2 and D2. With the increase in statistical accuracy of the data, it was found that a previously adopted procedure of linearly extrapolating to zero solid angle the partial cross sections measured at finite solid angles was not a sufficiently accurate procedure from which to deduce σT. The particle-neutron cross sections are derived by applying the Glauber screening correction to the difference between the particle-deuteron and particle-proton cross sections. The cross sections σT(π+d) and σT(π−d) are equal at all measured momenta, which confirms the validity of charge symmetry up to 20GeVc. Results are presented showing the variation of cross sections with momentum; evidence is presented for a small but significant decrease in σT(pp) [and σT(pn)] in the momentum region above 12GeVc.
The production of prompt muons ine+e− annihilation has been studied at centre of mass energies near 34.5 GeV. The measured semi-muonic branching ratios ofb andc quarks areB(b»Xμv) =0.117±0.028±0.01 andB(c→Xμv)=0.082 ±0.012a−0.01+0.02. The fragmentation functions of heavy quarks are hard, <zb>=0.85a−0.12–0.07+0.10+0.02 and <zc> =0.77a−0.07–0.11+0.05+0.03. Limits have been set on flavour changing neutral current decays:B(b→Xµ+µ−) <0.02 andB(b→Xµ+µ− (95% confidence level).
THE VALUE OF ASYMMETRY WAS DETERMINED USING A SAMPLE OF PROMPT MUONS.
We present an analysis of electroweak leptonic couplings from high statistics experiments on Bhabha scattering and μ pair production at an energy of 34.5 GeV. The forward-backward charge asymmetry of the μ pairs was measured to be −0.098±0.023±0.005. The data were found to agree well with the standard theory of electroweak interaction giving sin2θW=0.27±0.07. The leptonic weak couplings were determined to begv=0.000±0.170 andgA=−0.481±0.055. The data were also used to investigate a class of composite models for leptons.
No description provided.
No description provided.
We have measured π±p and pp elastic differential cross sections in the range |cosθc.m.|<0.35 for incident momenta from 2 to 9.7 GeV/c for π−p and pp and from 2 to 6.3 GeV/c for π+p. We find that the fixed-c.m.-angle πp differential cross sections cannot be described as simple functions of s. The data are compared to the energy and angular dependence predicted by the constituent model of Gunion, Brodsky, and Blankenbecler.
No description provided.
The differential cross section for π±−p elastic scattering at 180° was measured from 0.572 to 1.628 GeVc using a double-arm scintillation-counter spectrometer with an angular acceptance θ* in the center-of-mass system defined by −1.00≤cosθ*≤−0.9992. The π+−p cross section exhibits a large dip at 0.737 GeVc and a broad peak centered near 1.31 GeVc. The π−−p cross section exhibits peaks at 0.69, 0.97, and 1.43 GeVc.
No description provided.
Large-angle π±p elastic-scattering cross sections, measured between 2 and 9 GeV/c in fine intervals of incident momentum and scattering angle, are used to search for cross-section fluctuations occurring for small changes in the center-of-mass energy as suggested by Ericson and Mayer-Kuckuck and by Frautschi. Significant fluctuations are observed.
No description provided.
The differential cross sections for neutron-proton elastic charge-exchange scattering have been measured with a two-arm technique for incident neutron momenta between 22 and 65 GeV/ c and for values of the momentum transfer squared between 0.002 and 0.8 (GeV/ c ) 2 . The sharp forward peak observed previously at lower energies is also present at momenta up to 65 GeV/ c ; however the s dependence of the cross section is slowing down.
We present the general properties of jets produced bye+e− annihilation. Their production and fragmentation characteristics have been studied with charged particles for c.m. energies between 12 and 43 GeV. In this energy rangee+e− annihilation into hadrons is dominated by pair production of the five quarksu, d, s, c andb. In addition, hard gluon bremsstrahlung effects which are invisible at low energies become prominent at the high energies. The observed multiplicity distributions deviate from a Poisson distribution. The multiplicity distributions for the overall event as well as for each event hemisphere satisfy KNO scaling to within ∼20%. The distributions ofxp=2p/W are presented; scale breaking is observed at the level of 25%. The quantityxpdδ/dxp is compared with multigluon emission calculations which predict a Gaussian distribution in terms of ln(1/x). The observed energy dependence of the maximum of the distributions is in qualitative agreement with the calculations. Particle production is analysed with respect to the jet axis and longitudinal and transverse momentum spectra are presented. The angular distribution of the jet axis strongly supports the idea of predominant spin 1/2 quark pair production. The particle distributions with respect to the event plane show clearly the growing importance of planar events with increasing c.m. energies. They also exclude the presence of heavy quark production,e+e−→Q\(\bar Q\) for quark masses up to 5<mQ<20.3 GeV (|eQ|=2/3) and 7<mQ<19 GeV (|eQ|=1/3). The comparison of 1/σtotdδ/dpT measured at 14, 22 and 34 GeV suggests that hard gluon bremsstrahlung contributes mainly to transverse momenta larger than 0.5 GeV/c. The rapidity distribution forW≧22 GeV shows an enhancement away fromy=0 which corresponds to an increase in yield of 10–15% compared to the centre region (y=0). The enhancement probably results from heavy quark production and gluon bremsstrahlung. The particle flux around the jet axis shows with increasing c.m. energy a rapidly growing number of particles collimated around the jet axis, while at large angles to the jet axis almost noW dependence is observed. For fixed longitudinal momentump‖ approximate “fan invariance” is seen: The shape of the angular distribution around the jet axis is almost independent ofW. The collimation depends strongly onp‖. For smallp‖,p‖<0.2 GeV/c, isotropy is observed. With increasingp‖ the particles tend to be emitted closer and closer to the jet axis.
R VALUES BELOW 32.5 GEV ARE IDENTICAL TO THOSE GIVEN IN BRANDELIK ET AL., PL 113B, 499 (1982).
No description provided.
CHARGED PARTICLE MULTIPLICITY DISTRIBUTIONS.
Transverse particle momenta have been measured ine+e− annihilation into hadrons at c.m. energies between 9.4 and 31.6 GeV. The data are fully corrected for detector effects and radiation in the initial state. A comparison is made with recent QCD calculations.
MEASUREMENTS MADE WITH RESPECT TO THE SPHERICITY AXIS.
MEASUREMENTS MADE WITH RESPECT TO THE THRUST AXIS.
MEASUREMENTS MADE WITH RESPECT TO THE MOST ENERGETIC PARTON AXIS.
Forum