We discuss the resummation of next-to-leading logarithms (NLL) in heavy quark production near threshold. Results are presented for top quark production at the Fermilab Tevatron.

In reconstructing the top quark momentum from its decay products, one must account for extra jets that can result from radiation of gluons. In this paper we study soft gluon radiation in top production and decay at the Fermilab Tevatron. We consider the cases where one or both W bosons decays hadronically, i.e., where at least one of the top quarks can be fully reconstructed. We show results fo...

There has recently been surprising progress in understanding the spin and flavor dependence of deep inelastic structure functions in terms of the same physics needed in the simple quark models used for hadronic spectroscopy. However, the corresponding scale is usually very low, casting doubt on the use of leading order QCD evolution. We show that the conclusions are not significantly altered if...

In a recent paper a model of quark and lepton masses was proposed. Without any family symmetries almost all the qualitative and quantitative features of the quark and lepton masses and KobayashiMaskawa mixing angles are explained, primarily as consequences of various aspects of SO(10) symmetry. Here the model is discussed in much greater detail. The threefold mass hierarchy as well as the relat...

We have searched for production of tt̄ pairs in pp̄ interactions at 1.8 TeV center-of-mass energy at the FNAL Tevatron collider. The search assumes standard model decay for top quark into W + b quark. We observe in e+ jets and μ+ jets final states a small, not statistically significant, excess above the background estimated by two different methods. The results presented are preliminary.

The recent evidence for neutrino oscillations stimulate us to discuss again the problem of fermion masses and mixings in gauge theories. In the standard model, several forms for quark mass matrices are equivalent. They become ansatze within most extensions of the standard model, where also relations between quark and lepton sectors may hold. In a seesaw framework, these relations can constrain ...