72 research outputs found
Mathematical Formulas for Calculating Net Returns from Participation in Government Farm Programs: Provisions of the Food, Agricultural, Conservation and Trade Act of 1990
Agricultural and Food Policy, Agricultural Finance,
An Economic Comparison of Composted Manure and Commercial Nitrogen with Imperfect Information
The economic feasibility of fertilizing irrigated grain sorghum with compos ted manure is evaluated using net return budgeting and production function analysis. Although the use of compost is technically feasible, the economic analysis indicates that compost does not comprise a large percentage of the nitrogen source in the profit-maximizing combination with commercial fertilizer.Composted manure, commercial nitrogen, net returns budgeting, production function analysis, irrigated grain sorghum, Crop Production/Industries,
Multi-Parton Amplitudes in Gauge Theories
In this report we review recent developments in perturbation theory methods
for gauge theories. We present techniques and results that are useful in the
calculation of cross sections for processes with many final state partons which
have applications in the study of multi-jet phenomena in high-energy Colliders.Comment: 84 pages, 12 figures: Latex, preprint version of 1991 Physics Reports
article. Scanned Figure
Measurement of the p\bar{p}\sqrt{s}$ = 1.8 TeV
We update the measurement of the top production cross section using the CDF
detector at the Fermilab Tevatron. This measurement uses decays to
the final states +jets and +jets. We search for quarks from
decays via secondary-vertex identification or the identification of
semileptonic decays of the and cascade quarks. The background to the
production is determined primarily through a Monte Carlo simulation.
However, we calibrate the simulation and evaluate its uncertainty using several
independent data samples. For a top mass of 175 , we measure
pb and pb using
the secondary vertex and the lepton tagging algorithms, respectively. Finally,
we combine these results with those from other decay channels and
obtain pb.Comment: The manuscript consists of 130 pages, 35 figures and 42 tables in
RevTex. The manuscript is submitted to Physical Review D. Fixed typo in
author lis
Measurement of the Helicity of W Bosons in Top Quark Decays
We use the transverse momentum spectrum of leptons in the decay chain t-->bW
with W-->l nu to measure the helicity of the W bosons in the top quark rest
frame. Our measurement uses a ttbar sample isolated in 106 +/- 4 inverse
picobarns of data collected in ppbar collisions at sqrt(s)=1.8 TeV with the CDF
detector at the Fermilab Tevatron. Assuming a standard V--A weak decay, we find
that the fraction of W's with zero helicity in the top rest frame is F_0 = 0.91
+/- 0.37 (stat) +/- 0.13 (syst), consistent with the standard model prediction
of F_0=0.70 for a top mass of 175 GeV/c**2.Comment: Submitted to PRL. 8 pages, 2 figure
Search for a Fourth-Generation Quark More Massive than the Z0 Boson in ppbar Collisions at sqrt(s) = 1.8 TeV
We present the results of a search for pair production of a fourth-generation
charge -1/3 quark (b') in sqrt(s)=1.8 TeV ppbar collisions using 88 pb^(-1) of
data obtained with the Collider Detector at Fermilab. We assume that both
quarks decay via the flavor-changing neutral current process b' -> bZ and that
the b' mass is greater than m_Z + m_b. We studied the decay mode b'b'bar -> ZZ
b bbar where one Z0 decays into e^+e^- or mu^+ mu^- and the other decays
hadronically, giving a signature of two leptons plus jets. An upper limit on
the cross section of ppbar -> b'b'bar times [BR (b' -> bZ)]^2 is established as
a function of the b' mass. We exclude at 95% confidence level a b' quark with
mass between 100 and 199 GeV/c^2 for BR(b' -> bZ) = 100%.Comment: 12 pages, 2 figures, submitted to Phys. Rev. Letters on 9/12/9
WW Production Cross Section and W Branching Fractions in e+e- Collisions at 189 GeV
From a data sample of 183 pb^-1 recorded at a center-of-mass energy of roots
= 189 GeV with the OPAL detector at LEP, 3068 W-pair candidate events are
selected. Assuming Standard Model W boson decay branching fractions, the W-pair
production cross section is measured to be sigmaWW = 16.30 +- 0.34(stat.) +-
0.18(syst.) pb. When combined with previous OPAL measurements, the W boson
branching fraction to hadrons is determined to be 68.32 +- 0.61(stat.) +-
0.28(syst.) % assuming lepton universality. These results are consistent with
Standard Model expectations.Comment: 22 pages, 5 figures, submitted to Phys. Lett.
Further Properties of High-Mass Multijet Events at the Fermilab Proton-Antiproton Collider
The properties of high-mass multijet events produced at the Fermilab
proton-antiproton collider are compared with leading order QCD matrix element
predictions, QCD parton shower Monte Carlo predictions, and the predictions
from a model in which events are distributed uniformly over the available
multibody phase-space. Multijet distributions corresponding to (4N-4) variables
that span the N-body parameter space are found to be well described by the QCD
calculations for inclusive three-jet, four-jet, and five-jet events. The
agreement between data, QCD Matrix Element calculations, and QCD parton shower
Monte Carlo predictions suggests that 2 -> 2 scattering plus gluon radiation
provides a good first approximation to the full LO QCD matrix element for
events with three, four, or even five jets in the final state.Comment: 49 pages with 19 figures. Submitted to Phys. Rev. D. PostScript with
full resolution figures also available at
http://www-cdf.fnal.gov/physics/pub96/cdf3480_multijet_prd_draft3.p
Search For Charged Higgs Decays of the Top Quark Using Hadronic Decays of the Tau Lepton
This Letter describes a direct search for charged Higgs boson production in
proton-antiproton collisions at sqrt(s)=1.8 TeV recorded by the Collider
Detector at Fermilab. Two-Higgs-doublet extensions to the standard model
predict the existence of charged Higgs bosons. In such models, the branching
fraction for top quarks B(t --> H b --> tau nu b) can be large. This search
uses the hadronic decays of the tau lepton in this channel to significantly
extend previous limits on charged Higgs production.Comment: 6pages, 4 figures, 1 table; LaTeX; submitted to PR
Study of the heavy flavor content of jets produced in association with W bosons in collisions at = 1.8 TeV
We present a detailed examination of the heavy flavor content of the +
jet data sample collected with the CDF detector during the 1992-1995 collider
run at the Fermilab Tevatron. Jets containing heavy flavor quarks are selected
via the identification of secondary vertices or semileptonic decays of and
quarks. There is generally good agreement between the rates of secondary
vertices and soft leptons in the data and in the standard model simulation
including single and pair production of top quarks. An exception is the number
of events in which a single jet has both a soft lepton and a secondary vertex
tag. In 2,3 jet data, we find 13 such events where we expected 4.4
0.6 events. The kinematic properties of this small sample of events are
statistically difficult to reconcile with the simulation of standard model
processes.Comment: 77 pages, 19 tables, 23 figure
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