We present results of searches for diphoton resonances produced both inclusively and also in association with a vector boson (W or Z) using 100 $pb^{-1}$ of $p\bar{p}$ collisions using the CDF detector. We set upper limits on the product of cross section times branching ratio for both $p\bar{p} \to \gamma \gamma + X$ and $p \bar{p} \to \gamma \gamma + W/Z$. Comparing the inclusive production to the expectations from heavy sgoldstinos we derive limits on the supersymmetry-breaking scale $\sqrt{F}$ in the TeV range, depending on the sgoldstino mass and the choice of other parameters. Also, using a NLO prediction for the associated production of a Higgs boson with a W or Z boson, we set an upper limit on the branching ratio for $H \to \gamma \gamma$. Finally, we set a lower limit on the mass of a 'bosophilic' Higgs boson (e.g. one which couples only to $\gamma, W,$ and $Z$ bosons with standard model couplings) of 82 GeV/$c^2$ at 95% confidence level.
No description provided.
No description provided.
Bottom quark production in pbar-p collisions at sqrt(s)=1.8 TeV is studied with 5 inverse picobarns of data collected in 1995 by the DO detector at the Fermilab Tevatron Collider. The differential production cross section for b jets in the central rapidity region (|y(b)| < 1) as a function of jet transverse energy is extracted from a muon-tagged jet sample. Within experimental and theoretical uncertainties, DO results are found to be higher than, but compatible with, next-to-leading-order QCD predictions.
No description provided.
We present measurements of the b-bbar production cross section and angular correlations using the D0 detector at the Fermilab Tevatron p-pbar Collider operating at sqrt(s) = 1.8 TeV. The b quark production cross section for |y(b)|<1.0 and p_T(b)>6 GeV/c is extracted from single muon and dimuon data samples. The results agree in shape with the next-to-leading order QCD calculation of heavy flavor production but are greater than the central values of these predictions. The angular correlations between b and bbar quarks, measured from the azimuthal opening angle between their decay muons, also agree in shape with the next-to-leading order QCD prediction.
No description provided.
The errors are combinations of statistical and systematic uncertainties.
The distribution of MU+ MU- azimuthal angle difference.
Antiproton-proton elastic scattering was measured at c.m.s. energies √s =546 and 1800 GeV in the range of four-momentum transfer squared 0.025<-t<0.29 GeV2. The data are well described by the exponential form ebt with a slope b=15.28±0.58 (16.98±0.25) GeV−2 at √s =546 (1800) GeV. The elastic scattering cross sections are, respectively, σel=12.87±0.30 and 19.70±0.85 mb.
Final results (systematic errors included).
Final results (systematic errors included).
Statistical errors only. Data supplied by S. Belforte.
Inclusive jet cross sections have been measured in p¯p collisions at √s =546 and 1800 GeV, using the Collider Detector at Fermilab. The ratio of jet cross sections is compared to predictions from simple scaling and O(as3) QCD. Our data exclude scaling and lie (1.5–2.4)σ below a range of QCD predictions.
Additional systematic uncertainty +23,-26 pct.
Additional systematic uncertainty +-16 pct.
Additional systematic uncertainty +-0.22.
The general characteristics of inelastic proton-antiproton collisions at the CERN SPS Collider are studied with the UA1 detector using magnetic and calorimetric analysis. Results are presented on charged particle multiplicities and transverse and longitudinal momenta, and on total transverse energy distributions at centre of mass energies ranging from 0.2 to 0.9 TeV.
No description provided.
Invariant cross section of charged hadrons.
Inclusive cross section for single charged hadrons as a function of PT for the pseudorapdity region 0.8 to 4 for centre of mass energy 900 GeV.. Data read from plot.
The production of Λ 's and Ξ − 's in proton-antiproton collisions at 200 and 900 GeV c.m. energy has been studied using decays observed in the UA5 streamer chambers. The results are compared to previously published 546 GeV data, to results from other experiments, and to four theoretical models. The Λ yield per inelastic event is estimated to be 0.42±0.11 at 200 GeV and 0.66±0.14 at 900 GeV. We find a mean number of Ξ − 's per inelastic collision of 0.03 −0.02 +0.04 at 200 GeV and 0.06 −0.03 +0.05 at 900 GeV. The average transverse momentum of Λ's in the rapidity region | y |⩽2 is found to be 0.80 −0.14 +0.20 GeV/ c at 200 GeV and 0.74±0.09 GeV/ c at 900 GeV. The average transverse momentum of Ξ − 's in the rapidity region | y |⩽3 is estimated to be 0.8 −0.2 +0.4 GeV/ c at 200 GeV and 0.7 −0.1 +0.2 GeV/ c at 900 GeV which is lower than the unexpectedly high value of 1.1±0.2 GeV/ c measured at 546 GeV. The ratio of Ξ − production to Λ production in the region | y |⩽2, p t >1 GeV/ c is 0.07 −0.04 +0.08 at 900 GeV. This value is consistent with the ratio found in e + e − collisions and lower energy pp collisions but lower than the value obtained at 546 GeV. The average particle composition of events at 200 and 900 GeV, estimated using UA5 data, is presented.
Corrected lambda transverse momentum distributions. Numerical values supplied by F. Lotse. Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.
Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.
Corrected lambda transverse momentum distributions. Numerical values supplied by F. Lotse. Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.
Results on inclusive kaon production at 200 and 900 GeV centre of mass (CM) energy obtained with the UA5 detector at the pulsed CERN SPS antiproton-proton Collider are presented and compared with our earlier data at 546 GeV. The average transverse momentum 〈 p t 〉 of kaons has been estimated to be (0.50±0.04) GeV/ c at 200 GeV and (0.63±0.03) GeV/ c at 900 GeV in the central region and shows an increase with CM energy that is smore rapid than that expected from previous ISR data. The yield of kaons per inelastic p p event is found to be (0.72±0.12) at 200 GeV and (1.31±0.14) at 900 GeV. Finally, the K/π ratio has been found to exhibit a very slow increase with CM energy.
No description provided.
Single diffraction dissociation was measured in the reaction p¯p→p¯X at the centre-of-mass energy √ s = 546 GeV. The mass M of the system X was deduced from the pseudorapidity distribution of the observed charged tracks. The cross section of single diffraction dissociation for M 2 /s⩽0.05isσ sd =9.4 ± 0.7 mb. Comparison to the ISR data shows that σ sd increases with energy less fast than the total and the elastic cross sections.
No description provided.
New data are presented on charged particle pseudorapidity distributions for inelastic events produced at c.m. energies\(\sqrt s \)=200 and 900 GeV. The data were obtained at the CERN antiproton-proton Collider operated in a new pulsed mode. The rise of the central density ρ(0) at energies up to\(\sqrt s \)=900 GeV has been studied. A new form of central region scaling is found involving the densityρn(0) for charged multiplicityn, namely that the scaled central densityρn(0)/ρ(0) expressed as a function ofz=n/〈n〉 is independent ofs. Scaling in the fragmentation region holds to 10–20%, and the small amount of scalebreaking observed here could be accommodated within the framework suggested by Wdowcyk and Wolfendale to account for both accelerator and cosmic ray data.
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