We present a new next-to-leading order calculation for fully differential single-topquark final states. The calculation is performed using phase space slicing and dipole subtraction methods. The results of the methods are found to be in agreement. The dipole subtraction method calculation retains the full spin dependence of the final state particles. We show a few numerical results to illustrate the utility and consistency of the resulting computer implementations.

Physics at the Large Hadron Collider (LHC) and the International e + e − Linear Collider (ILC) will be complementary in many respects, as has been demonstrated at previous generations of hadron and lepton colliders. This report addresses the possible interplay between the LHC and ILC in testing the Standard Model and in discovering and determining the origin of new physics. Mutual benefits for the physics programme at both machines can occur both at the level of a combined interpretation of Hadron Collider and Linear Collider data and at the level of combined analyses of the data, where results obtained at one machine can directly influence the way analyses are carried out at the other machine. Topics under study comprise the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics. The status of the work that has been carried out within the LHC / LC Study Group so far is summarised in this report. Possible topics for future studies are outlined.4

Higgs bosons with enhanced coupling to bottom quarks are copiously produced at hadron colliders via bb → h, where the initial b quarks reside in the proton sea. We revisit the calculation of the next-to-leading-order cross section for this process and argue that the appropriate factorization scale for the b distribution functions is approximately m h /4, rather than m h , as had been previously assumed. This greatly improves the convergence of the perturbation series, and yields a result with mild factorization-scale dependence. We also show that the leading-order calculation of gg → bbh, integrated over the momenta of the final-state particles, is very sensitive to the factorization and renormalization scales. For scales of order m h /4 the gg → bbh cross section is comparable to that of bb → h, in contrast to the order-of-magnitude discrepancy between these two calculations for the scale m h . The result we obtain improves the prospects for Higgs-boson discovery at hadron colliders for large values of tan β.

I present an analysis of fully differential single-top-quark production plus jets at next-to-leading order. I describe the effects of jet definitions, top-quark mass, and higher orders on the shapes and normalizations of the kinematic distributions, and quantify all theoretical uncertainties. I explain how to interpret next-to-leading-order jet calculations, and compare them to showering event generators. Using the program ZTOP, I show that HERWIG and PYTHIA significantly underestimate both s-channel and t-channel single-top-quark production, and propose a scheme to match the relevant samples to the next-to-leading-order predictions.Comment: 40 pgs., revtex4, 35 ps figs; added Fig. 4, 1 Ref., minor clarifications, to appear in Phys. Rev.

Single-top-quark production probes the charged-current weak interaction of the top quark, and provides a direct measurement of the CKM matrix element V_{tb}. We perform two independent analyses to quantify the accuracy with which the W-gluon fusion (gq -> t\bar{b}q) and (q\bar{q} -> t\bar{b}) signals can be extracted from the backgrounds at both the Tevatron and the LHC. Although perturbation theory breaks down at low transverse momentum for the W-gluon fusion \bar{b} differential cross section, we show how to obtain a reliable cross section integrated over low \bar{b} transverse momenta up to a cutoff. We estimate the accuracy with which V_{tb} can be measured in both analyses, including theoretical and statistical uncertainties. We also show that the polarization of the top quark in W-gluon fusion can be detected at the Fermilab Tevatron and the CERN LHC.Comment: Version to appear in PRD, 31 pages, LaTeX, 8 ps figure