FOCUS 

My research focuses on high-energy physics, in particular collider physics. For the past few years, I have concentrated on di-boson production; that is, the production of WZ, W-photon, and Z-photon pairs (the W and Z bosons are the carriers of the weak force) at the Tevatron Collider, located at Fermi National Accelerator Laboratory (Fermilab) about forty miles west of Chicago. The Tevatron collides protons and antiprotons at a center of mass energy of 1800 GeV.

Di-boson production is interesting because it opens new ways to test the Glashow-Weinberg-Salam (GWS) model of electroweak interactions. The GWS model is based on a nonabelian gauge theory with gauge group SU(2) x U(1). Because of its gauge theory nature, the GWS model exactly predicts the self-interactions of W and Z bosons and photons, and these self-interactions can be tested in W and Z boson pair production.

In a series of research papers, I have reported on calculations of these processes at leading order and next-to-leading order in perturbation theory. Monte Carlo event generators have been made available to experimenters, which allow a realistic simulation of di-boson production in Tevatron experiments. A few of these papers are listed below.

More recently, I have become interested in how electroweak radiative corrections and multiple photon radiation shift the experimentally measured W and Z boson masses.

SELECTED PROJECTS

• QCD corrections to Z-gamma production in hadronic collisions for general ZZ-gamma and Z-gamma-gamma couplings.
• Electroweak corrections to W production in hadronic collisions
• W-gamma-gamma production and anomalous WW-gamma-gamma couplings
• Probing the weak boson sector in ZZ production at hadron colliders
  

PUBLICATIONS

• U. Baur, S. Keller, and D. Wackeroth. Electroweak radiative corrections to W boson production in hadronic collisions. Phys. Rev. D 59:013002 (1999).
• U. Baur, S. Keller, and W. K. Sakumoto. QED radiative correction to Z boson production and the forward-backward asymmetry at hadron colliders. Phys. Rev. D 57:199 (1998).
• U. Baur, T. Han, N. Kauer, R. Sobey, and D. Zeppenfeld. W-gamma-gamma production at the Fermi National Accelerator Laboratory (Fermilab) Tevatron Collider: Gauge invariance and radiation amplitude zero. Phys. Rev. D 56:140 (1997).
• U. Baur, T Han, and J. Ohnemus. QCD corrections and nonstandard three vector boson couplings in W+W- production at hadron colliders. Phys. Rev. D 53:1098 (1996).
• U. Baur and D. Zeppenfeld. Finite width effects and gauge invariance in radiative W production and decay. Phys. Rev. Lett. 75:1002 (1995).

Fig.1 Feynman diagrams for the pro-cess qq' ~ 2vyy.Permutations of the final state photons and the W boson are not shown explicitly.