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Abstract:

We present measurements of correlated bbÌ„ cross sections, μ-μ, correlations, the average B0µþÌ„0 mixing parameter χ̄, and a limit on the CP-violating parameter ∈B. For these measurements, we use muon pairs from bb double semileptonic decays. The data used in this analysis were taken with the Collider_Detector at Fermilab and represent an integrated luminosity of 17.4±0.6 pb-1. The results concerning bbÌ„ production correlations are compared to predictions of next-to-leading order QCD computations.

Abstract:

A strong signal for double parton (DP) scattering is observed in a [Formula presented] sample of [Formula presented] data from the CDF experiment at the Fermilab Tevatron. In DP events, two separate hard scatterings take place in a single [Formula presented] collision. We isolate a large sample of data [Formula presented] of which 53% are found to be DP. The process-independent parameter of double parton scattering, [Formula presented] is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings in separate [Formula presented] collisions. The result [Formula presented] represents a significant improvement over previous measurements, and is used to constrain simple models of parton spatial density. The Feynman [Formula presented] dependence of [Formula presented] is investigated and none is apparent. Further, no evidence is found for kinematic correlations between the two scatterings in DP events. © 1997 The American Physical Society.

Abstract:

We present the first observation of the all hadronic decay of tt^― pairs. The analysis is performed using 109 pb^−1 of pp^― collisions at s = 1.8 TeV collected with the Collider Detector at Fermilab. We observe an excess of events with five or more jets, including one or two b jets, relative to background expectations. Based on this excess we evaluate the production cross section to be in agreement with previous results. We measure the top mass to be 186±10±12 GeV/c². © 1997 The American Physical Society.

Abstract:

The dilepton mass spectrum in pp-→|+|-+X interactions is studied using dielectrons (ee) and dimuons (μμ) in 100 pb- of data collected with the Collider Detector at Fermilab. The data are consistent with standard model predictions. The mass spectrum, being a probe for new physics, is examined for new interactions of quarks and leptons from a common composite structure. Assuming a contact interaction with the conventional coupling g20/4π = 1, limits on chiral quark-electron and quark-muon compositeness scales in the range of 2.5 to 4.2 TeV are obtained. © 1997 The American Physical Society.

Abstract:

We report the observation and measurement of the rate of diffractive dijet production at the Fermilab Tevatron p^¯p collider at √s=1.8TeV. In events with two jets of ET>20GeV, 1.8<|η|<3.5, and η1η2>0, we find that the diffractive to nondiffractive production ratio is RJJ=[0.75±0.05(stat)±0.09(syst)]%. By comparing this result, in combination with our measured rate for diffractive W boson production reported previously, with predictions based on a hard partonic pomeron structure, we determine the pomeron gluon fraction to be fg=0.7±0.2. © 1997 American Physical Society.