Quantifying the power of multiple event interpretations

TL;DR

This paper demonstrates that using multiple event interpretations, such as different jet radii, significantly improves the sensitivity of Higgs to bb searches, even when combined with standard variables and realistic analysis methods.

Contribution

It introduces a generalized maximum likelihood method for incorporating multiple event interpretations in realistic experimental analyses.

Findings

Multiple jet radii improve significance over single radius.

Multiple interpretations provide additional information beyond standard variables.

Using multiple interpretations with BDTs enhances Higgs to bb search sensitivity.

Abstract

A number of methods have been proposed recently which exploit multiple highly-correlated interpretations of events, or of jets within an event. For example, Qjets reclusters a jet multiple times and telescoping jets uses multiple cone sizes. Previous work has employed these methods in pseudo-experimental analyses and found that, with a simplified statistical treatment, they give sizable improvements over traditional methods. In this paper, the improvement gain from multiple event interpretations is explored with methods much closer to those used in real experiments. To this end, we derive a generalized extended maximum likelihood procedure. We study the significance improvement in Higgs to bb with both this method and the simplified method from previous analysis. With either method, we find that using multiple jet radii can provide substantial benefit over a single radius. Another concern we address is that multiple event interpretations might be exploiting similar information to that already present in the standard kinematic variables. By examining correlations between kinematic variables commonly used in LHC analyses and invariant masses obtained with multiple jet reconstructions, we find that using multiple radii is still helpful even on top of standard kinematic variables when combined with boosted decision trees. These results suggest that including multiple event interpretations in a realistic search for Higgs to bb would give additional sensitivity over traditional approaches.