Top quark theory

Top quark in theory

Of the particles seen so far in collider experiments, the top quark is no doubt the most expensive, and the most glamorous. It is therefore the center of attention at the Tevatron and the LHC, until of course a new star, Higgs, comes along. Expressed less colloquially, the top quark is considered an interesting study object because it has many quantum numbers and thus couples to almost all othe...

High-precision Theory for Top-quark Production

Theory developments in differential top-quark distributions

Differential distributions for on-shell top-quark pair production at next-to-next-to-leading order in perturbative QCD for the Large Hadron Collider at √ s = 8 TeV are presented and discussed. The theoretical framework of the calculation is summarized. By comparing the prediction to measurements, it turns out that next-to-next-to-leading order corrections are necessary in order to resolve a dis...

Top quark production near threshold and the top quark mass

We consider top-anti-top production near threshold in e+e− collisions, resumming Coulomb-enhanced corrections at next-to-next-to-leading order (NNLO). We also sum potentially large logarithms of the small top quark velocity at the next-toleading logarithmic level using the renormalization group. The NNLO correction to the cross section is large, and it leads to a significant modification of the...

Top Quark Seesaw Theory of Electroweak Symmetry Breaking

We study electroweak symmetry breaking involving the seesaw mechanism of quark condensation. These models produce a composite Higgs boson involving the left-handed top quark, yet the top mass arises naturally at the observed scale. We describe a schematic model which illustrates the general dynamical ideas. We also consider a generic low-energy effective theory which includes several composite ...