Study of the proton-track reconstruction efficiency at GlueX using $\gamma~p \to \pi^+\pi^-\pi^+\pi^-~p_\text{miss}$ events

The analysis is based on PART files that are generated by the ReactionEfficiency plugin in halld_recon (needs at least commit 257a47e; see also PR #739). Scripts to run the plugin reside in launchPlugin.

The PART files are further processed by DSelector_pippippimpimpmiss.{h,C}, which is run over the data by runSelector.py. Currently, the produced custom ROOT trees need to be further processed by makeBruFitTree.py, which produces .root.brufit files.

These files contain the trees from which missing-mass squared distributions are generated. The proton peak in these distributions is fit using histogram-based shapes for signal and background that are extracted from bggen Monte Carlo. runFits.py is the master script that performs these fits and produces .pdf files with the result plots.

The fits are based on the BruFit package, which bins the data and performs the fits in the kinematic bins using RooFit. Currently, the boot branch and ROOT version 6.28 or higher are needed to run the fits.