Boosting the standard model Higgs signal with the Template Overlap Method

Abstract

We show that the Template Overlap Method can improve the signal to background ratio of boosted h → bb events produced in association with a leptonically decaying W . We introduce several improvements on the previous formulations of the template method. Varying three-particle template subcones increases the rejection power against the backgrounds, while the longitudinally invariant, sequential template generation ensures an efficient coverage in template phase space. We integrate b-tagging information into the template overlap framework and introduce a new template based observable, the template stretch. We further improve on the previous formulation of Template Planar Flow by including the effects of finite size subcones centered at each template momentum. Our analysis takes into account the contamination from the charm daughters of top decays in tt events, and includes nearly-realistic effects of pileup and underlying events. We show that the Template Overlap Method displays very low sensitivity to pileup, hence providing a self-contained alternative to other methods of pile up subtraction. The developments described in this work are quite general, and may apply to other searches for massive boosted objects.

Jet-images: computer vision inspired techniques for jet tagging

“…The techniques of jet substructure, which exploit the internal structure of the jet, have been developed for this task. Contemporary experimental and theoretical work in the field of jet substructure includes, but is not limited to, subjet finding and jet tagging / jet flavor identification algorithms [2][3][4][5][6][7][8][9][10][11][12], jet grooming and pileup mitigation [13][14][15], template and matrix element techniques [16,17], energy flow and event shapes [18][19][20][21][22][23][24], and probabilistic jet clustering [25,26]; more inclusive summaries can be found in references [27][28][29][30] Typical approaches to jet flavor identification and jet tagging begin with a simplified analytic expression of the system's behavior, such as the two-pronged nature of the hadronic W boson decay, or the large particle multiplicity of gluon initiated jets relative to quark initiated jets. A variable which capitalizes on this analytic knowledge and is ideally not subject to large theoretical uncertainties is derived.…”

LHC top partner searches beyond the 2 TeV mass region

“…Refs. [17,18] showed that the effects of pileup are not significant on TOM (up to 50 pileup events). The low susceptibility to pileup is a manifest of the fact that, by construction, TOM is sensitive mostly to the hard energy depositions within the fat jet and less so to the incoherent soft radiation.…”

“…Our study adopts the Template Overlap Method (TOM) [15][16][17][18] to tag the highly boosted decay product of the partners and in part reject the corresponding SM backgrounds. The final state of our signal events is characterized by multiple b-jets, which we employ through a semi-realistic b-tagging procedure.…”

“…[49][50][51]). Here, we use the TemplateTagger v.1.0 [43] implementation of the Template Overlap Method [15][16][17][18] as our boosted jet tagger, by virtue of the weak susceptibility of the method to pileup contamination. TOM approach to jet substructure aims to match the energy distribution of a jet to a parton-like configuration of heavy particle decays.…”

Top-antitop resonance searches beyond 1 TeV

“…A typical value for c in a tt -spectrum measurement without jet substructure top tagging is about 20 % (c = 0.2) [24]. (This number, and the selection efficiency, are expected to change if top tagging through jet substructure [25] is used in the analysis.) Thus, we get that the systematic and statistical uncertainties are of the same order provided that N ∼ 1/c 2 ≈ O(10).…”