Pineline: Industrialization of High-Energy Theory Predictions

Abstract

We present a collection of tools automating the efficient computation of large sets of theory predictions for high-energy physics. Calculating predictions for different processes often require dedicated programs. These programs, however, accept inputs and produce outputs that are usually very different from each other. The industrialization of theory predictions is achieved by a framework which harmonizes inputs (runcard, parameter settings), standardizes outputs (in the form of grids), produces reusable intermediate objects, and carefully tracks all meta data required to reproduce the computation. Parameter searches and fitting of non-perturbative objects are exemplary use cases that require a full or partial re-computation of theory predictions and will thus benefit of such a toolset. As an example application we present a study of the impact of replacing NNLO QCD K-factors in a PDF fit with the exact NNLO predictions.

Photons in the proton: implications for the LHC

“…Results are consistent with previous studies: specifically, we find that QED effects have a small but non-negligible impact mostly on the gluon PDF, and that photon-initiated contributions are most important for high-mass process such as neutral-current Drell-Yan production. This PDF determination is based on a new NNPDF pipeline for producing theory predictions [34]. Thanks to the integration of QED evolution in this pipeline, and in particular thanks to the use of the EKO evolution code [30], the production of QED variants of NNPDF determinations is now essentially automated, and will become the default in future releases.…”

“…Ref. [26]) have been recomputed using a modified version [34] of VRAP [57]. • The following datasets of Table 2.4 and Table 2.5 in Ref.…”

“…This new theory pipeline is described in Ref. [34]; it supersedes and replaces the one used for the NNPDF4.0 determination, which was based on a combination of different pieces of code of various origin, specifically APFEL [28] for PDF evolution and DIS structure function computation, and APFELgrid [29] for the generation of interpolation grids of NLO partonic matrix elements. This last piece of code made use of APPLgrid [53] and FastNLO [54] interpolators.…”

“…In particular, the APFEL [28] and APFELgrid [29] codes have been replaced by a suite of newly developed tools including the evolution equations solver EKO [30], the DIS structure functions calculator YADISM [31], and the interpolator of hard-scattering crosssections PineAPPL [32,33]. Taken together, they provide a pipeline for the efficient automatization of the computation of theory predictions [34]. An integral component of this theory pipeline is the use of interpolation grids in the format provided by PineAPPL [32,33], which can be interfaced to Monte Carlo generators.…”

Determination of the theory uncertainties from missing higher orders on NNLO parton distributions with percent accuracy

“…A first application of this methodology to the construction of a set of NLO PDFs with MHOUs, based on the NNPDF3.1 [13] PDF set and methodology, was also presented in these references, but no global NNLO PDF set with inclusion of MHOUs is currently available. Such a construction is now greatly facilitated by the availability of the EKO [14] evolution code, and its inclusion in a new pipeline for producing theory predictions for PDF determination [15], recently used for the construction of the NNPDF4.0QED PDF set [16] and currently adopted by NNPDF as a standard. Other approaches to the determination of MHOUs have been proposed [17][18][19][20][21][22]; also, MHOUs on NNLO PDFs have been recently estimated based on an approximate N 3 LO PDF determination [23].…”