The hadronic lineshape of the Z has been analyzed for evidence of signals of new, narrow vector resonances in the Z-mass range. The production rate of such resonances would be enhanced due to mixing with the Z. No evidence for new states is found, and it is thus possible to exclude, at the 95% confidence level, a quarkonium state in the mass range from 87.7 to 94.7 GeV.
Statistical errors only.
The first prompt photon measurement from the CDF experiment at the Fermilab pp¯ Collider is presented. Two independent methods are used to measure the cross section: one for high transverse momentum (PT) and one for lower PT. Comparisons to various theoretical calculations are shown. The cross section agrees qualitatively with QCD calculations but has a steeper slope at low PT.
Cross section using profile method and an isolation cut of 2 GeV in a cone around the photon. There is an additional 27 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
Cross section using conversion method and an isolation cut of 2 GeV in a cone around the photon. There is an additional +32,-46 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
Cross section using profile method and an isolation cut of 15 pct of the photon PT in a cone around the photon. There is an additional 29 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
The degree of excitation of the emulsion target nuclei due to nuclear interactions of oxygen and sulfur projectiles at 200 GeV/nucleon incident energy has been investigated. Using the plausible assumption that the numberNb of slow particles emitted from the struck target nucleus can be interpreted as a measure of the temperatureT of the residual nucleus, we have found that there exists a critical temperatureTc of the excited target nucleus. For Ag and Br target nuclei this temperature corresponds to <Nb>≌12 and it is attained when the impact parameters are less than about 4 fm.
No description provided.
No description provided.
Based on 520 000 fermion pairs accumulated during the first three years of data collection by the ALEPH detector at LEP, updated values of the resonance parameters of theZ are determined to beMZ=(91.187±0.009) GeV, ΓZ=(2.501±0.012) GeV, σhad0=(41.60±0.27) nb, andRℓ=20.78±0.13. The corresponding number of light neutrino species isNν=2.97±0.05. The forward-backward asymmetry in lepton-pair decays is used to determine the ratio of vector to axial-vector couplings of leptons:gV2(MZ2)/gA2(MZ2)=0.0052±0.0016. Combining this with ALEPH measurements of theb andc quark asymmetries and τ polarization gives sin2θWeff=0.2326±0.0013. Assuming the minimal Standard Model, and including measurements ofMW/MZ fromp\(\bar p\) colliders and neutrino-nucleon scattering, the mass of the top quark is\(M_{top} = 156 \pm \begin{array}{*{20}c} {22} \\ {25} \\ \end{array} \pm \begin{array}{*{20}c} {17} \\ {22Higgs} \\ \end{array} \) GeV.
Data from 1990 running period.
Data from 1990 running period.
Data from 1990 running period.
A new measurement of αs is obtained from the distributions in thrust, heavy jet mass, energy-energy correlation and two recently introduced jet broadening variables following a method proposed by Cata
Thrust distribution corrected for detector acceptance and initial state photon radiation.
Heavy jet mass (RHO) distribution (THRUST definition) corrected for detect or acceptance and initial state photon radiation.
Heavy jet mass (RHOM) distribution (MASS definition) corrected for detectoracceptance and initial state photon radiation.
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 strong coupling constant, αs, has been determined in hadronic decays of theZ0 resonance, using measurements of seven observables relating to global event shapes, energy correlatio
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
We have measured the analyzing power ANO and the spin transfer KNN for np-elastic scattering from about 60° to 170° c.m. at 485, 635, and 788 MeV. The new data clarify previous discrepancies and complete the first-order determination of nucleon-nucleon elastic scattering at these energies.
For definition of the POL(NAME=SPIN-TRANSFER) see text.
For definition of the POL(NAME=SPIN-TRANSFER) see text.
For definition of the POL(NAME=SPIN-TRANSFER) see text.
We present a measurement and comparison of the χc1 and χc2 production cross sections determined from interactions of 300-GeV/c π± and p with a Li target. We find χc1χc2 production ratios of 0.52−0.27+0.57 and 0.08−0.15+0.25 from reactions induced by π± and p, respectively.
The cross section per nucleon.
The cross section per nucleon. The differential cross section is fitted by the equation : D(SIG)/D(PT**2)= CONST*EXP(SLOPE*PT), D(SIG)/D(XL) = CONST*(1-(XL-CONST(C=X0))**2)**POWER(C=1) , and D(SIG)/D(XL) = CONST*(1-ABS(XL-CONST(C=XC)))**POWER(C=2).
The cross section per nucleon. The differential cross section is fitted by the equation : D(SIG)/D(COS(THETA)) = CONST*(1+CONST*COS(THETA)**2), where THETA is the angle between the MU+ and beam momentum in the CHI/C rest frame.
None
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).
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