Effective Field Theory in the top sector: do multijets help?

TL;DR

This paper investigates how including multijet events in top pair production analyses can improve constraints on effective field theory operators, addressing challenges in matching procedures and radiation modeling.

Contribution

It provides a detailed study of the impact of multijet events on EFT constraints and discusses the practical issues of matching and radiation in EFT analyses.

Findings

Multijet events can provide additional constraints on EFT operators.

Matching procedures do not significantly hinder EFT analyses in practice.

Including multijet data enhances sensitivity to new physics in top sector.

Abstract

Many studies of possible new physics employ effective field theory (EFT), whereby corrections to the Standard Model take the form of higher-dimensional operators, suppressed by a large energy scale. Fits of such a theory to data typically use parton level observables, which limits the datasets one can use. In order to theoretically model search channels involving many additional jets, it is important to include tree-level matrix elements matched to a parton shower algorithm, and a suitable matching procedure to remove the double counting of additional radiation. There are then two potential problems: (i) EFT corrections are absent in the shower, leading to an extra source of discontinuities in the matching procedure; (ii) the uncertainty in the matching procedure may be such that no additional constraints are obtained from observables sensitive to radiation. In this paper, we review why the first of these is not a problem in practice, and perform a detailed study of the second. In particular, we quantify the additional constraints on EFT expected from top pair plus multijet events, relative to inclusive top pair production alone.