4 research outputs found
Generating MHV super-vertices in light-cone gauge
We constructe the SYM lagrangian in light-cone gauge using
chiral superfields instead of the standard vector superfield approach and
derive the MHV lagrangian. The canonical transformations of the gauge field and
gaugino fields are summarised by the transformation condition of chiral
superfields. We show that MHV super-vertices can be described
by a formula similar to that of the MHV super-amplitude. In the
discussions we briefly remark on how to derive Nair's formula for
SYM theory directly from light-cone lagrangian.Comment: 25 pages, 7 figures, JHEP3 style; v2: references added, some typos
corrected; Clarification on the condition used to remove one Grassmann
variabl
The Twelve-Graviton Next-to-MHV Amplitude from Risager's Construction
The MHV or CSW expansion of tree-level Yang-Mills amplitudes provides an
elegant and simple way of obtaining analytic formulas for S-matrix elements.
Inspired by the BCFW technique, a systematic approach to obtain the MHV
expansion was introduced by Risager, using a particular complex deformation.
Although it works for Yang-Mills amplitudes, Risager's technique fails to
provide an MHV expansion already for Next-to-MHV gravity amplitudes with more
than eleven particles, as shown by Bianchi, Elvang and Freedman in 2008. This
fact implies that in this sector there is a contribution at infinity starting
at n = 12. In this note we determine the explicit analytic form of this residue
at infinity for n = 12. Together with the terms of the Risager MHV expansion,
the residue at infinity completes the first full CSW-like analytic expression
of the twelve-graviton NMHV amplitude. Our technique can also be used to
compute the residue at infinity for higher points.Comment: 12 pages, 2 figures, published version in JHEP; formerly titled "The
Anomaly of the Twelve-Graviton Next-to-MHV Risager Amplitude