A novel subtraction scheme for double-real radiation at NNLO

TL;DR

The paper introduces STRIPPER, a new subtraction scheme for NNLO QCD calculations involving double-real radiation, enabling efficient numerical evaluation of complex particle interactions.

Contribution

It presents a novel phase space decomposition and parameterization method that simplifies the derivation of subtraction terms without complex analytic integrations.

Findings

Enables numerical Monte Carlo evaluation of NNLO contributions

Facilitates handling of double-real radiation in particle physics

Improves computational efficiency for high-precision QCD calculations

Abstract

A general subtraction scheme, STRIPPER (SecToR Improved Phase sPacE for real Radiation), is derived for the evaluation of next-to-next-to-leading order (NNLO) QCD contributions from double-real radiation to processes with at least two particles in the final state at leading order. The result is a Laurent expansion in the parameter of dimensional regularization, the coefficients of which should be evaluated by numerical Monte Carlo integration. The two main ideas are a two-level decomposition of the phase space, the second one factorizing the singular limits of amplitudes, and a suitable parameterization of the kinematics allowing for derivation of subtraction and integrated subtraction terms from eikonal factors and splitting functions without non-trivial analytic integration.