Quantifying the Power of Multiple Event Interpretations

July 31, 2014

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.

Professor Matthew Schwartz and colleagus from Harvard and Los Alamos National Lab explored the improvement gain from multiple event interpretations with methods much closer to those used in real experiments. To this end, they derived a generalized extended maximum likelihood procedure and studied the significance improvement in Higgs to bb with both this method and the simplified method from previous analysis.

With either method, the researchers found that using multiple jet radii can provide substantial benefit over a single radius. Another concern they addressed was 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, they found 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. (Yang-Ting Chien, David Farhi, David Krohn, Andrew Marantan, David Lopez Mateos, Matthew Schwartz, "Quantifying the power of multiple event interpretations," arXiv:1407.2892 [hep-ph].)