Abstract
We present a new method for the local subtraction of infrared divergences at next-to-next-to-leading order (NNLO) in QCD, for generic infrared-safe observables. Our method attempts to conjugate the minimal local counterterm structure arising from a sector partition of the radiation phase space with the simplifications following from analytic integration of the counterterms. In this first implementation, the method applies to final-state massless particles. We show how our method compactly organises infrared subtraction at NLO, we deduce in detail the general structure of the subtraction terms at NNLO, and we provide a proof of principle with a complete application to a simple process at NNLO.
Highlights
In QCD is rapidly becoming the required accuracy standard for fixed-order predictions at LHC
We present a new method for the local subtraction of infrared divergences at next-to-next-to-leading order (NNLO) in QCD, for generic infrared-safe observables
Our method attempts to conjugate the minimal local counterterm structure arising from a sector partition of the radiation phase space with the simplifications following from analytic integration of the counterterms
Summary
V V features up to a quadruple IR pole in ; RR is finite in d = 4, but it is affected by up to four singularities in the double-radiation phase space, stemming from configurations that feature up to two soft and/or collinear emissions; RV has up to a double IR pole in , originating from its one-loop nature, on top of a double singularity in the single-radiation phase space The sum of these three contributions is finite due to the IR safety of X and to the KLN theorem. The sum of the four terms in the second line of eq (3.5) is both finite in d = 4 and integrable in the single-radiation phase space, making this contribution numerically tractable. In the first line of eq (3.5), the sum I (2) +I(RV) features the same poles in as V V , up to a sign, making the Born-like contribution finite and integrable
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