5,285 research outputs found
Top Charge Asymmetry -- Theory Status Fall 2013
I review the current status of the charge asymmetry in hadronic top-quark
pair production from a theory perspective. The standard-model predictions for
the observables at the Tevatron and LHC are being discussed, as well as
possible explanations of the Tevatron excess in terms of new physics. I give an
outlook for future investigations of the top-quark charge asymmetry, focussing
on novel observables at the LHC.Comment: prepared for the proceedings of "Top 2013 -- 6th International
Workshop on Top Quark Physics", Sep 14-19 2013, Durbach, German
Top-Quark Charge Asymmetry with a Jet Handle
Pairs of top and antitop quarks are produced at the LHC to a large extent in
association with a hard jet. We investigate the charge asymmetry in top pair +
jet production in quantum chromodynamics (QCD) and with additional massive
color-octet vector bosons. The total charge asymmetry at the LHC is suppressed
by the large charge-symmetric background from gluon-gluon fusion. We show to
what extent the asymmetry can be enhanced by suitable phase space cuts and, in
particular, elaborate on the kinematics of the hard jet in the top pair + jet
final state. We demonstrate that in QCD, the asymmetry amounts to -1.5% for
central jets without an excessive reduction of the cross section. By applying
additional kinematical cuts, the asymmetry can be enhanced to -4%, but at the
cost of a strong reduction of the cross section. Massive color-octet states can
generate sizeable effects in top pair + jet production, both on the charge
asymmetry and on the cross section. The charge asymmetry probes both vector and
axial-vector couplings to quarks. We show that massive color octets can
generate asymmetries up to +-10% for moderate and up to +-30% for strong
kinematical cuts to be used in experimental analyses at the LHC. Jet kinematics
can be used to obtain further information about the nature of the couplings and
thereby to discriminate between different models.Comment: 29 pages, 12 figure
Impacts of Selected Title I Provisions of the Senate Committee Farm Bill
This report examines selected provisions of Title I of the “Food and Energy Security Act of 2007,” as approved by the Senate Committee on Agriculture, Nutrition and Forestry.Agricultural and Food Policy, Food Security and Poverty, Resource /Energy Economics and Policy,
The Energy Independence and Security Act of 2007: Preliminary Evaluation of Selected Provisions
The “Energy Independence and Security Act (EISA) of 2007” was signed into law in December 2007. This report provides a snapshot of estimated impacts of selected provisions of EISA on biofuel and agricultural markets.Agricultural and Food Policy,
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