SFN_grids

Structure function grids

We provide pre-calculated structure function values at given x, Q^2 grids in the LHAPDF format.

For completeness, we also provide the CJ15 PDF grids with adjusted error bands: CJ15nlo_mod, which were used to calculate corresponding structure functions.

Usage:

• 1. install LHAPDF library from the official website
• 2. Set up $LHAPDF_PATH, and put downloaded grids under the path.
• 3. load LHAPDF module in python to read grids, and calculate structure functions or PDFs at desired x, Q^2. See plot_sfn.py and plot_pdf.ipynb in the top level src folder

SFn Index (ref: txgrids):

sfn_index	observable
900	F2 g
901	FL g
902	F2 gZ
903	FZ gZ
904	F3 gZ
905	F2 Z
906	FL Z
907	F3 Z
908	F2 NC
909	FL NC
910	F3 NC
930	F2 W-
931	FL W-
932	F3 W-
940	F2 W+
941	FL W+
942	F3 W+

Available grids:

CJ15nlo_mod_SFn: within the CJ15 framework, structure functions are calculated with rescaled uncertainties in each eigendirection to compensate for deviation from Gaussian behavior. Error sets provide a $\Delta\chi^2=1.646$ increase realtive to the central sets $\chi^2$, corresponding to a nominal 90% confidence level.

• Reference: appendix B in arXiv:2309.16851
• 49 sets in total. Set 0000 is the central value, 1-48 are error sets.
• Only F2 are available with higher twist. Others are all leading twist (LT)