arXiv : Identifying a new particle with jet substructures

Lim, Sung Hak; Han, Chengcheng; Kong, Kyoungchul; Kim, Minho; Kim, Doojin; Park, Myeonghun

doi:10.1007/JHEP01(2017)027

Article
Report number	arXiv:1609.06205 ; CTPU-16-19 ; IPMU16-0133 ; PITT-PACC-1608 ; CERN-TH-2016-218 ; CTPU-16-19 ; IPMU16-0133 ; PITT-PACC-1608
Title	Identifying a new particle with jet substructures
Author(s)	Lim, Sung Hak (IBS, Daejeon, CTPU ; KAIST, Taejon) ; Han, Chengcheng (Tokyo U., IPMU) ; Kim, Doojin (U. Florida, Gainesville (main) ; CERN) ; Kim, Minho (POSTECH, Pohang ; IBS, Daejeon, CTPU) ; Kong, Kyoungchul (Pittsburgh U. ; Kansas U.) ; Park, Myeonghun (IBS, Daejeon, CTPU)
Publication	2017-01-09
Imprint	20 Sep 2016
Number of pages	33
Note	36 pages, 11 figures, published in JHEP
In:	JHEP 01 (2017) 027
DOI	10.1007/JHEP01(2017)027
Subject category	hep-ex ; Particle Physics - Experiment ; hep-ph ; Particle Physics - Phenomenology
Abstract	We investigate a potential of measuring properties of a heavy resonance X, exploiting jet substructure techniques. Motivated by heavy higgs boson searches, we focus on the decays of X into a pair of (massive) electroweak gauge bosons. More specifically, we consider a hadronic Z boson, which makes it possible to determine properties of X at an earlier stage. For $m_X$ of O(1) TeV, two quarks from a Z boson would be captured as a "merged jet" in a significant fraction of events. The use of the merged jet enables us to consider a Z-induced jet as a reconstructed object without any combinatorial ambiguity. We apply a conventional jet substructure method to extract four-momenta of subjets from a merged jet. We find that jet substructure procedures may enhance features in some kinematic observables formed with subjets. Subjet momenta are fed into the matrix element associated with a given hypothesis on the nature of X, which is further processed to construct a matrix element method (MEM)-based observable. For both moderately and highly boosted Z bosons, we demonstrate that the MEM with current jet substructure techniques can be a very powerful discriminator in identifying the physics nature of X. We also discuss effects from choosing different jet sizes for merged jets and jet-grooming parameters upon the MEM analyses.
Copyright/License	arXiv nonexclusive-distrib. 1.0 preprint: © 2016-2025 CERN (License: CC-BY-4.0) publication: © 2017-2025 The Author(s) (License: CC-BY-4.0), sponsored by SCOAP³

$Parton-level Monte Carlo simulation results for $S \rightarrow HH/ZZ \rightarrow 4b$ with $M_S=1$ TeV. The upper-left panel shows unit-normalized $\Delta R_{bb}$ distributions for the Higgs boson (orange histogram) and the $Z$ gauge boson (blue histogram) cases. The red and blue dashed lines mark the positions corresponding to $R=0.8$ and $R=1.2$, respectively. The other three panels (upper-right for $H$, lower-left for $Z_L$, and lower-right for $Z_T$) show unit-normalized $\cos\theta$ distributions with cone sizes for MJs $R\leq 0.8$ (red histogram) and $R\leq 1.2$ (blue histograms) and compare them with corresponding theory predictions (solid black lines). Dashed vertical lines represent the upper bounds on $|\cos\theta|$ for a given $R_\MJ$ according to eq.~\eqref{eq:cosUpper}.$ $Parton-level Monte Carlo simulation results for $S \rightarrow HH/ZZ \rightarrow 4b$ with $M_S=1$ TeV. The upper-left panel shows unit-normalized $\Delta R_{bb}$ distributions for the Higgs boson (orange histogram) and the $Z$ gauge boson (blue histogram) cases. The red and blue dashed lines mark the positions corresponding to $R=0.8$ and $R=1.2$, respectively. The other three panels (upper-right for $H$, lower-left for $Z_L$, and lower-right for $Z_T$) show unit-normalized $\cos\theta$ distributions with cone sizes for MJs $R\leq 0.8$ (red histogram) and $R\leq 1.2$ (blue histograms) and compare them with corresponding theory predictions (solid black lines). Dashed vertical lines represent the upper bounds on $|\cos\theta|$ for a given $R_\MJ$ according to eq.~\eqref{eq:cosUpper}.$ $Parton-level Monte Carlo simulation results for $S \rightarrow HH/ZZ \rightarrow 4b$ with $M_S=1$ TeV. The upper-left panel shows unit-normalized $\Delta R_{bb}$ distributions for the Higgs boson (orange histogram) and the $Z$ gauge boson (blue histogram) cases. The red and blue dashed lines mark the positions corresponding to $R=0.8$ and $R=1.2$, respectively. The other three panels (upper-right for $H$, lower-left for $Z_L$, and lower-right for $Z_T$) show unit-normalized $\cos\theta$ distributions with cone sizes for MJs $R\leq 0.8$ (red histogram) and $R\leq 1.2$ (blue histograms) and compare them with corresponding theory predictions (solid black lines). Dashed vertical lines represent the upper bounds on $|\cos\theta|$ for a given $R_\MJ$ according to eq.~\eqref{eq:cosUpper}.$ Show more plots

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Record created 2016-09-22, last modified 2022-08-10

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