Theory updates for parton distributions in Hessian formalism

5 May 2026, 11:20
10m
Sala IMPERIALE A, First Floor (Hotel Carlton)

Sala IMPERIALE A, First Floor

Hotel Carlton

Flash talk WG1 Structure Functions and Parton Densities WG1 Structure functions and parton densities

Speaker

Petja Paakkinen (CERN)

Description

We present a new extension to the toolbox of parton-distribution reweighting methods, which enables a general user to study the impact of an updated theory prediction on the results of a pre-existing parton-distribution global analysis. This new method is a combination of the well-known reweighting method with a new deweighting variant where a dataset is removed from the original analysis in an approximative way. Specific use cases of this method could include e.g. testing the impact of updating the treatment of an observable from NnLO to Nn+1LO precision in the global analysis, or of including previously ignored electroweak, mass, or higher-twist effects, or even testing the impact of some beyond-standard-model physics. We discuss the implementation of this method in the Hessian formalism, and show its use in a single case study.

Speaker confirmation Yes

Authors

Petja Paakkinen (CERN) Hannu Paukkunen (University of Jyväskylä) Sami Yrjänheikki (University of Jyväskylä)

Presentation materials