25 research outputs found
Off-shell Currents and Color-Kinematics Duality
We elaborate on the color-kinematics duality for off-shell diagrams in gauge
theories coupled to matter, by investigating the scattering process , and show that the Jacobi relations for the kinematic numerators
of off-shell diagrams, built with Feynman rules in axial gauge, reduce to a
color-kinematics violating term due to the contributions of sub-graphs only.
Such anomaly vanishes when the four particles connected by the Jacobi relation
are on their mass shell with vanishing squared momenta, being either external
or cut particles, where the validity of the color-kinematics duality is
recovered. We discuss the role of the off-shell decomposition in the direct
construction of higher-multiplicity numerators satisfying color-kinematics
identity in four as well as in dimensions, for the latter employing the
Four Dimensional Formalism variant of the Four Dimensional Helicity scheme. We
provide explicit examples for the QCD process .Comment: Accepted version for publication in PLB. Manuscript extended: 19
pages, 15 figures; C/K duality for tree-level amplitudes in dimensional
regularization added; references added; title modifie
Adaptive Integrand Decomposition
We present a simplified variant of the integrand reduction algorithm for
multiloop scattering amplitudes in dimensions, which
exploits the decomposition of the integration momenta in parallel and
orthogonal subspaces, , where is the
dimension of the space spanned by the legs of the diagrams. We discuss the
advantages of a lighter polynomial division algorithm and how the orthogonality
relations for Gegenbauer polynomilas can be suitably used for carrying out the
integration of the irreducible monomials, which eliminates spurious integrals.
Applications to one- and two-loop integrals, for arbitrary kinematics, are
discussed.Comment: Conference Proceedings, Loops and Legs in Quantum Field Theory, 24-29
April 2016, Leipzig, German
Static two-body potential at fifth post-Newtonian order
We determine the gravitational interaction between two compact bodies up to
the sixth power in Newton's constant GN, in the static limit. This result is
achieved within the effective field theory approach to General Relativity, and
exploits a manifest factorization property of static diagrams which allows to
derive static post Newtonian (PN) contributions of (2n+1)-order in terms of
lower order ones. We recompute in this fashion the 1PN and 3PN static
potential, and present the novel 5PN contribution.Comment: 7 pages, 3 figures. In v2: references added, published on PR
On the interplay between the loop-tree duality and helicity amplitudes
The spinor-helicity formalism has proven to be very efficient in the
calculation of scattering amplitudes in quantum field theory, while the loop
tree duality (LTD) representation of multi-loop integrals exhibits appealing
and interesting advantages with respect to other approaches. In view of the
most recent developments in LTD, we exploit the synergies with the
spinor-helicity formalism to analyse illustrative one- and two-loop scattering
processes. We focus our discussion on the local UV renormalisation of IR and UV
finite amplitudes and present a fully automated numerical implementation that
provides efficient expressions which are integrable directly in four space-time
dimensions.Comment: 12 pages, 5 figures. In v2: discussion on the application of two-loop
local renormalisation added; references update