Showing papers by "Pierpaolo Mastrolia published in 2015"
TL;DR: In this paper, it was shown that the sub-leading soft term in single-gluon emission of quark-gluon amplitudes in QCD is controlled by differential operators, whose universal form can be derived from both on-shell recursion relation and gauge invariance.
Abstract: We elaborate on the radiative behaviour of tree-level scattering amplitudes in the soft regime. We show that the sub-leading soft term in single-gluon emission of quark-gluon amplitudes in QCD is controlled by differential operators, whose universal form can be derived from both on-shell recursion relation and gauge invariance, as it was shown to hold for graviton- and gluon-scattering.
43 citations
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TL;DR: In this paper, the color-kinematics duality of off-shell diagrams in axial gauge was investigated by investigating the scattering process and showing that the Jacobi relation for the kinematic numerators of offshell diagrams, built with Feynman rules, reduces to a color-kinematic violating term due to the contributions of subgraphs only.
Abstract: We elaborate on the color-kinematics duality for off-shell diagrams in gauge theories coupled to matter, by investigating the scattering process $gg\to ss, q\bar q, gg$, and show that the Jacobi relations for the kinematic numerators of off-shell diagrams, built with Feynman rules in axial gauge, reduces 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 this off-shell decomposition in the direct construction of higher-multiplicity numerators satisfying color-kinematics identity, providing an explicit example for the QCD process $gg\to q\bar{q}g$.
2 citations