13 research outputs found
Triple collinear splitting functions at NLO for scattering processes with photons
We present splitting functions in the triple collinear limit at next-to-leading order. The computation was performed in the context of massless QCD+QED, considering only processes which include at least one photon. Through the comparison of the IR divergent structure of splitting amplitudes with the expected known behavior, we were able to check our results. Besides that we implemented some consistency checks based on symmetry arguments and cross-checked the results among them. Studying photon-started processes, we obtained very compact results
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
Antenna subtraction for gluon scattering at NNLO
We use the antenna subtraction method to isolate the double real radiation
infrared singularities present in gluonic scattering amplitudes at
next-to-next-to-leading order. The antenna subtraction framework has been
successfully applied to the calculation of NNLO corrections to the 3-jet cross
section and related event shape distributions in electron-positron
annihilation. Here we consider processes with two coloured particles in the
initial state, and in particular two-jet production at hadron colliders such as
the Large Hadron Collider (LHC). We construct a subtraction term that describes
the single and double unresolved contributions from the six-gluon tree-level
process using antenna functions with initial state partons and show numerically
that the subtraction term correctly approximates the matrix elements in the
various single and double unresolved configurations.Comment: 71 pages, JHEP3 class; corrected typos, equivalent but more compact
version of eq. (5.12), results unchange
Antenna subtraction at NNLO with hadronic initial states: initial-final configurations
We extend the antenna subtraction method to include initial states containing one hadron at NNLO. We present results for all the necessary subtraction terms, antenna functions, for the master integrals required to integrate them over the relevant phase space and finally for the integrated antennae themselves. Where applicable, our results are cross-checked against the known NNLO coefficient functions for deep inelastic scattering processes
From multiple unitarity cuts to the coproduct of Feynman integrals
We develop techniques for computing and analyzing multiple unitarity cuts of Feynman integrals, and reconstructing the integral from these cuts. We study the relations among unitarity cuts of a Feynman integral computed via diagrammatic cutting rules, the discontinuity across the corresponding branch cut, and the coproduct of the integral. For single unitarity cuts, these relations are familiar. Here we show that they can be generalized to sequences of unitarity cuts in different channels. Using concrete one- and two-loop scalar integral examples we demonstrate that it is possible to reconstruct a Feynman integral from either single or double unitarity cuts. Our results offer insight into the analytic structure of Feynman integrals as well as a new approach to computing them