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Manuscript Title: FEWZ 2.0: A code for hadronic Z production at next-to-next-to-leading order
Authors: Ryan Gavin, Ye Li, Frank Petriello, Seth Quackenbush
Program title: FEWZ
Catalogue identifier: AEJP_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 182(2011)2388
Programming language: Fortran 77, C++, Python.
Computer: Mac, PC.
Operating system: Mac OSX, Unix/Linux.
Has the code been vectorised or parallelized?: Yes. User-selectable, 1 to 219
RAM: 200 Mbytes for common parton distribution functions
Keywords: NNLO, Z, Drell-Yan.
PACS: 12.15.Mm, 12.38.Bx, 13.85.Qk.
Classification: 11.1.

External routines: CUBA numerical integration library, numerous parton distribution sets (see text); these are provided with the code.

Nature of problem:
Determination of the Drell-Yan Z/photon production cross section and decay into leptons, with kinematic distributions of leptons and jets including full spin correlations, at next-to-next-to-leading order in the strong coupling constant.

Solution method:
Virtual loop integrals are decomposed into master integrals using automated techniques. Singularities are extracted from real radiation terms via sector decomposition, which separates singularities and maps onto suitable phase space variables. Result is convoluted with parton distribution functions. Each piece is numerically integrated over phase space, which allows arbitrary cuts on the observed particles. Each sample point may be binned during numerical integration, providing histograms, and reweighted by parton distribution function error eigenvectors, which provides PDF errors.

Output does not correspond to unweighted events, and cannot be interfaced with a shower Monte Carlo.

Running time:
One day for total cross sections with 0.1% integration errors assuming typical cuts, up to 1 week for smooth kinematic distributions with sub-percent integration errors for each bin.