Abstract
We calculate the one-loop correction to the soft-gluon current with massive fermions. This current is process independent and controls the singular behavior of one-loop massive QCD amplitudes in the limit when one external gluon becomes soft. The result derived in this work is the last missing process-independent ingredient needed for numerical evaluation of observables with massive fermions at hadron colliders at the next-to-next-to-leading order.
Highlights
The main obstacle for the numerical evaluation of collider observables at higher perturbative orders is the presence of infrared (IR) divergences in parton level calculations
At the next-to-leading order (NLO), this complication can be evaded within the so-called subtraction method
The subtraction approach can be applied to processes with massless and massive fermions
Summary
The main obstacle for the numerical evaluation of collider observables at higher perturbative orders is the presence of infrared (IR) (soft and collinear) divergences in parton level calculations. These divergences cancel in observables, but need to be regularized in all intermediate calculations by introducing an appropriate parameter (typically dimensionally). Its basic idea is simple: first, one utilizes the universality and factorization property of IR singularities to construct an approximation to the corresponding real emission partonic amplitude. To construct a subtraction scheme at next-to-next-to-leading order (NNLO) one needs to know, among others, the limiting behavior of one-loop amplitudes when one of the external on-shell partons - a gluon becomes soft.
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