Selected Topics in Top Quark Physics

Abstract

I discuss three different selected topics in top quark physics. The first topic concerns the next-to-next-to-leading order calculation of the hadroproduction of top quark pairs and the role of multiple polylogarithms in this calculation. I report on an ongoing next-to-next-to-leading order calculation of heavy quark pair production in hadron collisions where the loop--by--loop part of the calculation is about to be completed. Calculating the loop-by-loop part allows one to take a glimpse at the mathematical structure of the full NNLO calculation. The loop-by-loop contributions bring in a new class of functions introduced only eight years ago by the Russian mathematician Goncharov called multiple polylogarithms. The second topic concerns a next-to-leading order calculation of unpolarized top quark decays which are analyzed in cascade fashion $t\to b+W^{+}$ followed by $W^{+}\to l^{+}+{\nu }_l$. Finally, I present some next-to-leading order results on polarized top quark decays which are analyzed in the top quark rest system.

Comments: 11 pages, 4 figures, Invited talk given at the 12th Regional Conference of Mathematical Physics, Islamabad, Pakistan, March 2006, to be published in the proceedings