Zack Sullivan

Understanding single-top-quark production and jets at hadron colliders

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.

Single-top-quark production via W -gluon fusion at next-to-leading order

Single-top-quark production via W-gluon fusion at hadron colliders provides an opportunity to directly probe the charged-current interaction of the top quark. We calculate the next-to-leading-order corrections to this process at the Fermilab Tevatron, the CERN Large Hadron Collider, and DESY HERA. Using a b-quark distribution function to sum collinear logarithms, we show that there are two independent corrections, of order 1/ln(m{sub t}{sup 2}/m{sub b}{sup 2}) and {alpha}{sub s}. This observation is generic to processes involving a perturbatively derived heavy-quark distribution function at an energy scale large compared with the heavy-quark mass. {copyright} {ital 1997} {ital The American Physical Society}

Higgs-boson production via bottom-quark fusion

Higgs bosons with enhanced coupling to bottom quarks are copiously produced at hadron colliders via

Higgs-Boson Production in Association with Bottom Quarks at Next-to-Leading Order

b\overline{b}\ensuremath{\rightarrow}h,

Single-top-quark production at hadron colliders

where the initial b quarks reside in the proton sea. We reexamine 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

Low-Energy Supersymmetry and the Tevatron Bottom-Quark Cross Section

{m}_{h}/4,

Trilepton production at the CERN LHC : standard model sources and beyond.

rather than

Direct probes of R-parity violating supersymmetric couplings via single top squark production

{m}_{h},

Top quark physics: Future measurements

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

Standard model explanation of a CDF dijet excess in W j j

g\stackrel{\ensuremath{\rightarrow}}{g}b\overline{b}h,