Abstract
A number of recent applications of jet substructure, in particular searches for light new particles, require substructure observables that are decorrelated with the jet mass. In this paper we introduce the Convolved SubStructure (CSS) approach, which uses a theoretical understanding of the observable to decorrelate the complete shape of its distribution. This decorrelation is performed by convolution with a shape function whose parameters and mass dependence are derived analytically. We consider in detail the case of the D2 observable and perform an illustrative case study using a search for a light hadronically decaying Z′. We find that the CSS approach completely decorrelates the D2 observable over a wide range of masses. Our approach highlights the importance of improving the theoretical understanding of jet substructure observables to exploit increasingly subtle features for performance.
Highlights
JHEP05(2018)002 with many of the most important observables in current use arising out of analytic calculations
We have shown how a given jet substructure observable, such as N2 or D2, can be decorrelated with the jet mass using an understanding of its perturbative and non-perturbative behavior
The shape function incorporates effects due to both perturbative and non-perturbative physics, and we used a recently derived factorization formula to analytically derive the mass dependence of both these contributions
Summary
We discuss the sources of correlation between a two-prong observable, such as D2, and the jet mass (for brevity, we will not always explicitly say groomed jet mass, we always work with groomed observables), to illustrate how these correlations arise. In this paper we will consider the concrete example of the D2 observable, for which a factorization formula is known [46, 47]. This allows us to make precise statements about the perturbative and non-perturbative behavior of the observable. For a jet with two prong substructure we have D2 1, while for a more standard QCD jet without a resolved substructure D2 ∼ 1
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