# Updating and Optimizing Error PDFs in the Hessian Approach. Part II

## TL;DR

This paper validates the { t ePump} software for updating parton distribution functions using the Hessian approach and demonstrates its application to LHC data impact analysis on PDFs.

## Contribution

The paper introduces a validation of the { t ePump} software against full global analyses and showcases its utility in LHC phenomenological studies.

## Key findings

- { t ePump} accurately reproduces full global analysis results.
- { t ePump} efficiently estimates the impact of new LHC data on PDFs.
- The software facilitates rapid updates of PDFs with minimal computational cost.

## Abstract

In an earlier publication, we introduced the software package, {\tt \texttt{ePump}} (error PDF Updating Method Package), that can be used to update or optimize a set of parton distribution functions (PDFs), including the best-fit PDF set and Hessian eigenvector pairs of PDF sets (i.e., error PDFs), and to update any other set of observables, in the Hessian approach. Here, we validate the {\tt \texttt{ePump}} program with a detailed comparison against a full global analysis, and we demonstrate the potential of {\tt \texttt{ePump}} by presenting selected phenomenological applications relevant to the Large Hadron Collider. For example, we use the package to estimate the impact of the recent LHC data of the measurements of $W$, $Z$ boson and top quark pair differential distributions on the CT14HERA2 PDFs.