nnpdf++ project, data files used by the code may be grouped into
two categories, theory and experiment. Experimental data and the information
pertaining to the treatment of systematic errors are held in
store the precomputed information for use when calculating theoretical
predictions corresponding to information held in the equivalent
file. In this section the file formats and naming conventions for these files
will be detailed, along with the directory structure employed by the
For NNPDF3.1 and later fits, a considerably larger number of theory options will be explored than in previous determinations. In NNPDF3.0 the main theory variations used were perturbative order, value of the strong coupling and the number of active flavours in the VFNS. For NNPDF3.1 and later, it has been necessary to accommodate variations in additional parameters, such as treatments of the heavy quark mass (pole vs MS-bar), scale variations, intrinsic charm, resummation effects etc. The book-keeping used to enable efficient variations of the theoretical treatment used in fits post-3.0 will therefore also be outlined here.
This section will begin by detailing the specifications for the file formats
used by the code, first with the experimental data file formats and layouts in
Experimental data files and secondly with the file formats used for
theoretical predictions in Theory data files. Finally the organisation of
these files within the
nnpdf++ structure will be described in
Organisation of data files.
In order to clarify the later description, here are a few important terminological points to note.
Dataset vs Experiment
When referring to a collection of data points two words are used in the
nnpdf++ code which have specific meanings. Dataset refers to the result
of a specific measurement, typically associated with a single experimental paper
and corresponds to the DataSet class in the
Experiment refers to a collection of Datasets which are associated
by experimental cross-correlations. For example, the ATLAS 2010 R=0.4 inclusive
jet measurement and the ATLAS 2011 high-mass Drell-Yan measurement are both
examples of Datasets as used in the NNPDF3.0 analysis. Both of these
datasets are grouped into the ATLAS Experiment as they have systematic
uncertainties that are cross-correlated with each other. In this document, when
using these terms in this sense, they will be italicised for clarity.
Note however that the concept of an Experiment is being phased out in the NNPDF code. For more information on this see Data specification.
Dataset and Experiment names
When referred to, the Dataset and Experiment names refer to the short identifying string used in the code for each Dataset and Experiment. For example, the Dataset name for the aforementioned ATLAS 2010 inclusive jet measurement with R=0.4 is ATLASR04JETS36PB.