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

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,

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,