QCD Corrections to Electroweak Annihilation Decays of Superheavy Quarkonia

QCD corrections to all the allowed decays of superheavy groundstate quarkonia into electroweak gauge and Higgs bosons are presented. For quick estimates, approximations that reproduce the exact results within less than at worst two percent are also given.Comment: 20 pages RevTeX, 9 figures. The complete paper, including figures, is also available via anonymous ftp at (129.13.102.139) as ftp://ttpux2.physik.uni-karlsruhe.de/ttp95-05/ttp95-05.ps, or via www at http://ttpux2.physik.uni-karlsruhe.de/cgi-bin/preprints

Electroweak effects in top-quark pair production at Hadron Colliders

Top-quark physics plays an important role at hadron colliders such as the Tevatron collider at Fermilab or the upcoming Large Hadron Collider (LHC) at CERN. Given the planned experimental precision, detailed theoretical predictions are mandatory. In this article we present analytic results for the complete electroweak corrections to gluon induced top-quark pair production, completing our earlier results for the quark-induced reaction. As an application we discuss top-quark pair production at Tevatron and at LHC. In particular we show that, although small for inclusive quantities, weak corrections can be sizeable for differential distribution

Maximizing phonon thermal conductance for ballistic membranes

At low temperatures, phonon scattering can become so weak that phonon transport becomes ballistic. We calculate the ballistic phonon conductance G for membranes using elasticity theory, considering the transition from three to two dimensions. We discuss the temperature and thickness dependence and especially concentrate on the issue of material parameters. For all membrane thicknesses, the best conductors have, counter-intuitively, the lowest speed of sound.Comment: 4 pages, 4 figures, proceedings to phonons 2007 conferenc

Recent highlights from BESIII: XYZ states

In this contribution we review recent results from the BESIII experiment. We focus on the investigation of XYZ states and the discovery of new charged charmonium - like structures. Two isospin triplets Z(3900) and Z(4020) have been discovered, decaying into π± J/ψ and π± hc, respectively. Structures with compatible parameters have been found decaying to DD̄∗ and D∗D̄∗, respectively, suggesting that these structures might be of the same origin. Furthermore, we have investigated the transition Y(4260) → γX(3872). This is the first observation of a radiative transition between XYZ states

QCD Corrections to Toponium Production at Hadron Colliders

Toponium production at future hadron colliders is investigated. Perturbative QCD corrections to the production cross section for gluon fusion are calculated as well as the contributions from gluon-quark and quark-antiquark collisions to the total cross section. The dependence on the renormalization and factorization scales and on the choice of the parton distribution functions is explored. QCD corrections to the branching ratio of $\eta_{t}$ into $\gamma\gamma$ are included and the two-loop QCD potential is used to predict the wave function at the origin. The branching ratio of $\eta_{t}$ into $\gamma Z$, $ZZ$, $HZ$ and $WW$ is compared with the $\gamma\gamma$ channel.Comment: 16 pages (latex) 9 figures (postscript) available upon request, TTP92-3