A covariant representation of the Ball-Chiu vertex

Understand

In nonabelian gauge theory the three-gluon vertex function contains important structural information, in particular on infrared divergences, and is also an essential ingredient in the Schwinger-Dyson equations.

• Much effort has gone into analyzing its general structure, and at the one-loop level also a number of explicit computations have been done, using various approaches.
• Here we use the string-inspired formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in all cases.
• The vertex is computed fully off-shell and in dimensionally continued form, so that it can be used as a building block for higher-loop calculations.