75 research outputs found
Quantum MHV Diagrams
Over the past two years, the use of on-shell techniques has deepened our
understanding of the S-matrix of gauge theories and led to the calculation of
many new scattering amplitudes. In these notes we review a particular on-shell
method developed recently, the quantum MHV diagrams, and discuss applications
to one-loop amplitudes. Furthermore, we briefly discuss the application of
D-dimensional generalised unitarity to the calculation of scattering amplitudes
in non-supersymmetric Yang-Mills.Comment: 17 pages, 7 figures; based on two talks given at the 7th Workshop On
Continuous Advances In QCD, 11-14 May 2006, Minneapolis, Minnesot
Branes at Singularities in Type 0 String Theory
We consider Type 0B D3-branes placed at conical singularities and analyze in
detail the conifold singularity. We study the non supersymmetric gauge theories
on their worldvolume and their conjectured dual gravity descriptions. In the
ultraviolet the solutions exhibit a logarithmic running of the gauge coupling.
In the infrared we find confining solutions and IR fixed points.Comment: 18 pages, uses BibTeX, ssg.bs
Comments on (Non-)Chiral Gauge Theories and Type IIB Branes
We use type IIB brane configurations which were recently suggested by Hanany
and Zaffaroni to study four dimensional N=1 supersymmetric gauge theories. We
calculate the one loop beta function and realize Seiberg's duality using a
particular configuration. We also comment on the anomaly cancelation condition
in the case of chiral theories and the beta function in the case of chiral and
SO/Sp theories.Comment: 11 pages, Latex. 5 figures. Several changes in text and a reference
was added. Accepted to Phys.Lett.
MHV One-Loop Amplitudes in Yang-Mills from Generalised Unitarity
In this letter, we exploit generalised unitarity in order to calculate the
cut-constructible part of one-loop amplitudes in non-supersymmetric Yang-Mills
theory. In particular, we rederive the n-gluon MHV amplitudes for both the
adjacent and non-adjacent gluon helicity configurations from 3- and 4-particle
cuts alone.Comment: 20 pages, 4 figures; v3 version published in JHE
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