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No description provided.
No description provided.
No description provided.
The properties of events having the topology and kinematic features of double Pomeron exchange are described. The data were taken at the CERN pp¯ collider at s=0.63 TeV in the UA1 detector. A calorimeter trigger was used to isolate events in which a central cluster of particles was separated from forward particles by large rapidity gaps. The invariant mass M of the central cluster (possibly a colliding Pomeron-Pomeron system) covers the range 10-70 GeV/c2. The M dependence of charged particle multiplicity distributions in these double Pomeron events is strikingly different from their s dependence in pp and pp¯ interactions.
Pseudorapidity distribution for charged particle tracks in the DPE data.
Pseudorapidity distribution for charged particle tracks in the MB events.
Mean charged particle multiplicity as function of the invariant mass of the charged particles in DPE events.
Results on the production of charged hadrons in muon-deuteron and muon-xenon interactions are presented. The data were taken with the E665 spectrometer, which was exposed to the 490 GeV muon beam of the Tevatron at Fermilab. The use of a streamer chamber as vertex detector provides nearly 4π acceptance for charged particles. The μD data are compared with the μXe data in terms of multiplicity distributions, average multiplicities, forward-backward multiplicity correlations, rapidity and transverse momentum distributions and of two-particle rapidity correlations of charged hadrons. The data cover a range of invariant hadronic massesW from 8 to 30 GeV.
Results of negative binomial function fit to the multiplicity distribution of charged hadrons in muon-deuteron scattering. DISPERSION = SQRT(1/MULT + 1/K) is this dispersion of the scaled multiplicity Z = N/MULT.
Results of negative binomial function fit to the multiplicity distribution of charged hadrons in muon-xenon scattering. DISPERSION = SQRT(1/MULT + 1/K) is this dispersion of the scaled multiplicity Z = N/MULT.
Results of negative binomial fits to charged hadron multiplicity distributions in muon-deuteron interactions for backward and forward hemispheres of the hadronic cm.
Fermilab Experiment-665 measured deep-inelastic scattering of 490 GeV muons off deuterium and xenon targets. Events were selected with a range of energy exchange ν from 100 GeV to 500 GeV and with large ranges of Q2 and xBj: 0.1 GeV2/c2
Showing effect of shadowing in the ratios of cross sections.
Showing effect of shadowing in the ratios of cross sections.
Showing effect of shadowing in the ratios of cross sections.
Measurements of elastic photoproduction cross sections for the J / ψ meson from 100 GeV to 375 GeV are presented. The results indicate that the cross section increases slowly in this range. The shape of the energy dependence agrees well with the photon-gluon fusion model prediction.
Data supplied by V. Paolone.
Cross section data using Bethe-Heitler event normalization.
Cross section data using the Beam Gamma Monitor normalization.
A precise measurement of p̄p elastic scattering in the Coulomb-strong interaction interference region was performed at the CERN Sp̄pS Collider at a centre-of-mass energy of 541 GeV. The ratio of the real to the imaginary part of the forward elastic scattering amplitude was found to be ρ = 0.135 ± 0.015. The slope of the exponential fall off of the strong interaction part was also measured to be b = 15.5 ± 0.1 GeV −2 .
No description provided.
Real part of amplitude extracted using a more precise UA4 measurement. (1 +RE(AMP)/IM(AMP)**2)SIG(TOT) = 63.5 +- 1.5 MB (Bozzo et al. PL 147B(1984)392).
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THE AZIMUTHAL ANGLE DISTRIBUTIONS OF PI0 HAVE BEEN FITTED BY: D(N)/D(PHI)=N*(1+CONST(Q=1)*COS(PHI)+CONST(Q=2)*COS(2*PHI)), WHERE PHI IS THE AZIMUTHAL ANGLEOF PI0 RELATIVE TO THE FOLLOWING COORDINATE SYSTEM: Z AXIS DIRECTED ALONG BEAM MOMENTUM, X AXIS DIRECTED ALONG TRANSVERSE MOMENTUM CONSTRUCTED FROM TRANSVERSE MOMENTA OF THE FINAL STATE PARTICLES (SEE PAPER). THE 17 PCT OF ALL NONPERIPHERAL EVENTS HAS BEEN REMOVED (SEE PAPER).
THE AZIMUTHAL ANGLE DISTRIBUTIONS OF CHARGED PARTICLES HAVE BEEN FITTED BY : D(N)/D(PHI)=N *(1+CONST(Q=1)*COS(PHI)+CONST(Q=2)*COS(2*PHI)), WHERE PHI IS THEAZIMUTHAL ANGLE OF CHARGED PARTICLE RELATIVE TO THE FOLLOWING COORDINATE SYSTEM : Z AXIS DIRECTED ALONG BEAM MOMENTUM, X AXIS DIRECTED ALONG TRANSVERSE MOMENTU M CONSTRUCTED FROM TRANSVERSE MOMENTA OF THE FINAL STATE PARTICLES (SEE PAPER). A systematic error of 0.03 has been estimated for CONST(Q=1) and CONST(Q= 2).
THE AZIMUTHAL ANGLE DISTRIBUTIONS OF NEUTRONS HAVE BEEN FITTED BY: D(N)/D (PHI)=N *(1+CONST(Q=1)*COS(PHI)+CONST(Q=2)*COS(2*PHI)), WHERE PHI IS THE AZIMUTHAL ANGLE OF NEUTRON RELATIVE TO THE FOLLOWING COORDINATE SYSTEM: Z AXIS DIRECTEDALONG BEAM MOMENTUM, X AXIS DIRECTED ALONG TRANSVERSE MOMENTUM CONSTRUCTED FRO M TRANSVERSE MOMENTA OF THE FINAL STATE PARTICLES (SEE PAPER). A systematic error of 0.03 has been estimated for CONST(Q=1) and CONST(Q= 2).
A study of the fragmentation properties of charm and bottom quarks intoD mesons is presented. From 263 700Z0 hadronic decays collected in 1991 with the DELPHI detector at the LEP collider,D0,D+ andD*+ are reconstructed in the modesK−π+,K−π+K+ andD0π+ followed byD0→K−π+, respectively. The fractional decay widths\(\Gamma {{(Z^0\to {D \mathord{\left/ {\vphantom {D {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}X)} \mathord{\left/ {\vphantom {{(Z^0\to {D \mathord{\left/ {\vphantom {D {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}X)} {\Gamma _h }}} \right. \kern-\nulldelimiterspace} {\Gamma _h }}\) are determined, and first results are presented for the production ofD mesons from\(c\bar c\) and\(b\bar b\) events separately. The average energy fraction ofD*± in charm quark fragmentation is found to be 〈XE(D*)〉c=0.487±0.015 (stat)±0.005 (sys.). Assuming that the fraction ofDs and charm-baryons produced at LEP is similar to that around 10 GeV, theZ0 partial width into charm quark pairs is determined to beΓc/Γh=0.187±0.031 (stat)±0.023 (sys). The probability for ab quark to fragment into\(\bar B_s \) orb-baryons is inferred to be 0.268±0.094 (stat)±0.100 (sys) from the measured probability that it fragments into a\(\bar B^0 \) orB−.
Using full data sample.
Using full data sample with proper time > 1 ps to enrich (b bbar) content.
Data with Delta(L) > 1.
Data taken with the Collider Detector at Fermilab (CDF) during the 1988–1989 run of the Tevatron are used to measure the distribution of the center-of-mass (rest frame of the initial state partons) angle between isolated prompt photons and the beam direction. The shape of the angular distribution for photon-jet events is found to be significantly different from that observed in dijet data. The QCD predictions show qualitative agreement with the observed prompt photon angular distribution.
Background subtracted normalised prompt photon angular distribution.
The production dynamics of baryon-antibaryon pairs are investigated using hadronic Z 0 decays, recorded with the OPAL detector, which contain at least two identified Λ baryons. The rapidly difference for Λ Λ pairs shows the correlations expected from models with a chain-like production of baryon-antibaryon pairs. If the baryon number of a Λ is compensated by a Λ , the Λ is found with a probability of 53% in an interval of ±0.6 around the Λ rapidity. This correlation strength is weaker than predicted by the Herwig Monte Carlo and the Jetset Monte Carlo with a production chain of baryon-antibaryon, and stronger than predicted by the UCLA model. The observed rapidity correlations can be described by the Jetset Monte Carlo with a dominant production chain of baryon-meson-antibaryon, the popcorn mechanism. In addition to the short range correlations, one finds an indication of a correlation of Λ Λ pairs in opposite hemispheres if both the Λ and the Λ have large rapidities. Such long range correlations are expected if the primary quark flavours are compensated in opposite hemispheres and if these quarks are found in energetic baryons. Rates for simultaneous baryon and strangeness number compensation for Λ Λ , Ξ − Ξ + and Ξ − Λ ( Λ + Λ ) are measured and compared with different Monte Carlo models.
No description provided.
Opposite and same baryon number invariant PI P mass distribuition for additional LAMBDA(LAMBDABAR) candidates in events with one identified LAMBDA(LAMBDABAR). CT.= Data read from plot.
Opposite and same baryon number invariant PI P mass distribuition for additional LAMBDA(LAMBDABAR) candidates in events with one identified XI-(XIBAR+). CT.= Data read from plot.
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