Upcoming Duality Seminar: corrected title

[Nancy Partridge <nancyp physics harvard edu>]

Thursday, April 15, 2010  4:15 PM
Harvard University
Duality Seminar
"The Next-to-Simplest Quantum Field Theories "
Suvrat Raju
(HRI)
Jefferson Lab, 453

Refreshments in the high energy theory coffee area, 4th floor Jefferson, 
at 3:45.

Abstract:
We apply newly-developed techniques for studying perturbative scattering 
amplitudes to gauge theories with matter. It is well known that the N=4 
SYM theory has a very simple S-matrix; do other gauge theories see 
similar simplifications in their S-matrices? It turns out the one-loop 
gluon S-matrix simplifies if the matter representations satisfy some 
group theoretic constraints. In particular, these constraints can be 
expressed as linear Diophantine equations involving the higher order 
Indices (or higher-order Casimirs) of these representations. We solve 
these constraints to find examples of theories whose gluon scattering 
amplitudes are as simple as those of the N=4 theory. This class includes 
the N=2, SU(K) theory with a symmetric and anti-symmetric tensor 
hypermultiplet. Non-supersymmetric theories with appropriately tuned 
matter content can also see remarkable simplifications. We find an 
infinite class of non-supersymmetric amplitudes that are 
cut-constructible even though naive power counting would suggest the 
presence of rational remainders.