Previously, I calculated the tracking resolution (sigma) as a function of the Monte-Carlo pT (pTmc):

https://drupal.star.bnl.gov/STAR/blog/dmawxc/update-04132018-run-9-pp-track-phi-eta-pt-resolution

I can now extract the width of the resolution as a function of pTmc.  To calculate this, I split the tracking resolution distribution into slices of 0.5 GeV/c in pTmc.  Then each slice was fitted with a Gaussian.  The widths of these Gaussians, which I'll call varsigma here, are plotted below and fit with a line.