On the Model Dependence of Fiducial Cross Section Measurements in View of Reinterpretations

TL;DR

This paper investigates how assumptions of the Standard Model influence the interpretation of fiducial cross section measurements, highlighting potential biases in reinterpretations for new physics searches.

Contribution

It quantifies the model bias introduced by detector correction procedures in fiducial cross section measurements using simulations of LHC detector responses.

Findings

Model bias is negligible only in specific cases.

Reinterpretations require careful evaluation of migration effects.

Precise final state definitions are essential for accurate new physics constraints.

Abstract

Fiducial production cross sections measurements of Standard Model processes, in principle, provide constraints on new physics scenarios via a comparison of the predicted Standard Model cross section and the observed cross section. This approach received significant attention in recent years, both from direct constraints on specific models and the interpretation of measurements in the view of effective field theories. A generic problem in the reinterpretations of Standard Model measurements is the corrections applied to data to account for detector effects. These corrections inherently assume the Standard Model to be valid, thus implying a model bias of the final result. In this work, we study the size of this bias by studying several new physics models and fiducial phase-space regions. The studies are based on fast detector simulations of a generic multi-purpose detector at the Large Hadron Collider. We conclude that the model bias in the associated reinterpretations is negligible only in specific cases. An evaluation of potential migration effects, as well as a precise definition of the final state signatures, has to be performed before any new physics reinterpretation effort.