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Title: Resolving combinatorial ambiguities in dilepton t t ¯ event topologies with constrained M 2 variables

Abstract

We advocate the use of on-shell constrained $${M}_{2}$$ variables in order to mitigate the combinatorial problem in supersymmetry-like events with two invisible particles at the LHC. We show that in comparison to other approaches in the literature, the constrained $${M}_{2}$$ variables provide superior ansätze for the unmeasured invisible momenta and therefore can be usefully applied to discriminate combinatorial ambiguities. We illustrate our procedure with the example of dilepton $$t\overline{t}$$ events. We critically review the existing methods based on the Cambridge $${M}_{T2}$$ variable and MAOS reconstruction of invisible momenta, and show that their algorithm can be simplified without loss of sensitivity, due to a perfect correlation between events with complex solutions for the invisible momenta and events exhibiting a kinematic endpoint violation. Then we demonstrate that the efficiency for selecting the correct partition is further improved by utilizing the $${M}_{2}$$ variables instead. Finally, we also consider the general case when the underlying mass spectrum is unknown, and no kinematic endpoint information is available.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Univ. of Kansas, Lawrence, KS (United States); Univ. of Florida, Gainesville, FL (United States); European Organization for Nuclear Research (CERN), Geneva (Switzerland)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1398745
Alternate Identifier(s):
OSTI ID: 1498897
Grant/Contract Number:  
[SC0010296; FG02-12ER41809; SC0007863]
Resource Type:
Published Article
Journal Name:
Physical Review D
Additional Journal Information:
[Journal Name: Physical Review D Journal Volume: 96 Journal Issue: 7]; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; leptonic, semileptonic & radiative decays; top quark; Hadron colliders

Citation Formats

Debnath, Dipsikha, Kim, Doojin, Kim, Jeong Han, Kong, Kyoungchul, and Matchev, Konstantin T. Resolving combinatorial ambiguities in dilepton t t ¯ event topologies with constrained M 2 variables. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.96.076005.
Debnath, Dipsikha, Kim, Doojin, Kim, Jeong Han, Kong, Kyoungchul, & Matchev, Konstantin T. Resolving combinatorial ambiguities in dilepton t t ¯ event topologies with constrained M 2 variables. United States. doi:10.1103/PhysRevD.96.076005.
Debnath, Dipsikha, Kim, Doojin, Kim, Jeong Han, Kong, Kyoungchul, and Matchev, Konstantin T. Mon . "Resolving combinatorial ambiguities in dilepton t t ¯ event topologies with constrained M 2 variables". United States. doi:10.1103/PhysRevD.96.076005.
@article{osti_1398745,
title = {Resolving combinatorial ambiguities in dilepton t t ¯ event topologies with constrained M 2 variables},
author = {Debnath, Dipsikha and Kim, Doojin and Kim, Jeong Han and Kong, Kyoungchul and Matchev, Konstantin T.},
abstractNote = {We advocate the use of on-shell constrained ${M}_{2}$ variables in order to mitigate the combinatorial problem in supersymmetry-like events with two invisible particles at the LHC. We show that in comparison to other approaches in the literature, the constrained ${M}_{2}$ variables provide superior ansätze for the unmeasured invisible momenta and therefore can be usefully applied to discriminate combinatorial ambiguities. We illustrate our procedure with the example of dilepton $t\overline{t}$ events. We critically review the existing methods based on the Cambridge ${M}_{T2}$ variable and MAOS reconstruction of invisible momenta, and show that their algorithm can be simplified without loss of sensitivity, due to a perfect correlation between events with complex solutions for the invisible momenta and events exhibiting a kinematic endpoint violation. Then we demonstrate that the efficiency for selecting the correct partition is further improved by utilizing the ${M}_{2}$ variables instead. Finally, we also consider the general case when the underlying mass spectrum is unknown, and no kinematic endpoint information is available.},
doi = {10.1103/PhysRevD.96.076005},
journal = {Physical Review D},
number = [7],
volume = [96],
place = {United States},
year = {2017},
month = {10}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1103/PhysRevD.96.076005

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Cited by: 1 work
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