Dr. Carola Berger, SLAC
Bootstrapping One-Loop Amplitudes (Needles and Large Haystacks)
January 22, 2007

The Large Hadron Collider (LHC) at CERN will provide a wealth of data in the
very near future which will shed light on the mechanism of electroweak
symmetry breaking and possibly discover new physics. However, in the
hadronic environment of the LHC, most events have high-multiplicity final
states and very complex signatures. Thus searching for the Higgs or new
physics is comparable to looking for a needle in a gigantic haystack. A
successful search then requires, among other things, an understanding of the
expected Standard Model background. This in turn necessitates precision
calculations of these scattering processes. One of the main bottlenecks in
such calculations is the computation of multi-leg one-loop amplitudes. I
present a new technique for the calculation of such amplitudes based on
on-shell recursion relations. The technique currently works for massless QCD
amplitudes, but as I will illustrate, an extension to massive amplitudes
seems feasible and should greatly simplify the computation of amplitudes
relevant for scattering processes at the LHC.