9,458 research outputs found
Effective axial-vector coupling of gluon as an explanation to the top quark asymmetry
We explore the possibility that the large forward-backward
asymmetry measured by the CDF detector at Tevatron could be due to a universal
effective axial-vector coupling of gluon. Using an effective field theory
approach we show model independently how such a log-enhanced coupling occurs at
1-loop level. The interference with QCD gluon vector coupling naturally induces
the observed positive forward-backward asymmetry that grows with
invariant mass and is consistent with the cross section measurements.
This scenario does not involve new flavor changing couplings nor operators that
interfere with QCD, and, therefore, is not constrained by the LHC searches for
4-quark contact interactions. We predict top quark polarization effects that
grow with energy and allow to test this scenario at the LHC. Our proposal
offers a viable alternative to new physics scenarios that explain the
forward-backward asymmetry anomaly with the interference between QCD and tree
level new physics amplitudes.Comment: Few small changes in the text, same as published version, 5 pages, 2
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Readmission Rates and Their Impact on Hospital Financial Performance: A Study of Washington Hospitals
This longitudinal study examines whether readmission rates, made transparent through Hospital Compare, affect hospital financial performance by examining 98 hospitals in the State of Washington from 2012 to 2014. Readmission rates for acute myocardial infarction (AMI), pneumonia (PN), and heart failure (HF) were examined against operating revenues per patient, operating expenses per patient, and operating margin. Using hospital-level fixed effects regression on 276 hospital year observations, the analysis indicated that a reduction in AMI readmission rates is related with increased operating revenues as expenses associated with costly treatments related with unnecessary readmissions are avoided. Additionally, reducing readmission rates is related with an increase in operating expenses. As a net effect, increased PN readmission rates may show marginal increase in operating margin because of the higher operating revenues due to readmissions. However, as readmissions continue to happen, a gradual increase in expenses due to greater use of resources may lead to decreased profitability
Quark Model Calculations Of Symmetry Breaking in Parton Distributions
Using a quark model, we calculate symmetry breaking effects in the valence
quark distributions of the nucleon. In particular, we examine the breaking of
the quark model SU(4) symmetry by color magnetic effects, and find that color
magnetism provides an explanation for deviation of the ratio
from . Additionally, we calculate the effect of charge symmetry breaking
in the valence quark distributions of the proton and neutron and find, in
contrast to other authors, that the effect is too small to be seen
experimentally.Comment: 6 Pages, 3 postscript figures compressed using uufile
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