Comparing efficient computation methods for massless QCD tree amplitudes: Closed Analytic Formulae versus Berends-Giele Recursion
arXiv:1206.2381 · doi:10.1103/PhysRevD.87.034011
Abstract
Recent advances in our understanding of tree-level QCD amplitudes in the massless limit exploiting an effective (maximal) supersymmetry have led to the complete analytic construction of tree-amplitudes with up to four external quark-anti-quark pairs. In this work we compare the numerical efficiency of evaluating these closed analytic formulae to a numerically efficient implementation of the Berends-Giele recursion. We compare calculation times for tree-amplitudes with parton numbers ranging from 4 to 25 with no, one, two and three external quark lines. We find that the exact results are generally faster in the case of MHV and NMHV amplitudes. Starting with the NNMHV amplitudes the Berends-Giele recursion becomes more efficient. In addition to the runtime we also compared the numerical accuracy. The analytic formulae are on average more accurate than the off-shell recursion relations though both are well suited for complicated phenomenological applications. In both cases we observe a reduction in the average accuracy when phase space configurations close to singular regions are evaluated. We believe that the above findings provide valuable information to select the right method for phenomenological applications.
22 pages, 9 figures, Mathematica package GGT.m and example notebook is included in submission
References in corpus (18)
- An Automated Implementation of On-Shell Methods for One-Loop Amplitudes
- Assault on the NLO Wishlist: pp -> tt bb
- Precise Predictions for W + 4 Jet Production at the Large Hadron Collider
- Complete off-shell effects in top quark pair hadroproduction with leptonic decay at next-to-leading order
- NLO QCD corrections to pp -> t anti-t b anti-b + X at the LHC
- NLO QCD corrections to WWbb production at hadron colliders
- Helac-Phegas: a generator for all parton level processes
- All tree-level amplitudes in N=4 SYM
- W+3 jet production at the Tevatron
- Next-to-leading order QCD predictions for W+W+jj production at the LHC
- On the Numerical Evaluation of One-Loop Amplitudes: the Gluonic Case
- All tree-level amplitudes in massless QCD
- Numerical NLO QCD calculations
- NLO QCD corrections to five-jet production at LEP and the extraction of alpha_s(M_Z)
- A comparison of efficient methods for the computation of Born gluon amplitudes
- Efficient Tree-Amplitudes in N=4: Automatic BCFW Recursion in Mathematica
- Multi-gluon one-loop amplitudes numerically
- Thread-Scalable Evaluation of Multi-Jet Observables