Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector

A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb¯, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying lept...

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Autores principales: Alconada Verzini, María Josefina, Alonso, Francisco, Arduh, Francisco Anuar, Dova, María Teresa, Monticelli, Fernando Gabriel, Wahlberg, Hernán Pablo, The ATLAS Collaboration
Formato: Articulo
Lenguaje:Inglés
Publicado: 2015
Materias:
Ciencias Exactas
Física
FCNC Interactions
Hadron-Hadron Scattering
Higgs Physics
Top Physics
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/86926
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-86926
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Exactas
Física
FCNC Interactions
Hadron-Hadron Scattering
Higgs Physics
Top Physics
spellingShingle Ciencias Exactas
Física
FCNC Interactions
Hadron-Hadron Scattering
Higgs Physics
Top Physics
Alconada Verzini, María Josefina
Alonso, Francisco
Arduh, Francisco Anuar
Dova, María Teresa
Monticelli, Fernando Gabriel
Wahlberg, Hernán Pablo
The ATLAS Collaboration
Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector
topic_facet Ciencias Exactas
Física
FCNC Interactions
Hadron-Hadron Scattering
Higgs Physics
Top Physics
description A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb¯, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at √s = 8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb<sup>-1</sup>. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt¯ → WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t → Hc and t → Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H → γγ and H → WW*, ττ decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |λ<sub>tcH</sub>| and |λ<sub>tuH</sub>| couplings are 0.13 (0.10) and 0.13 (0.10) respectively. These are the most restrictive direct bounds on tqH interactions measured so far.
format Articulo
Articulo
author Alconada Verzini, María Josefina
Alonso, Francisco
Arduh, Francisco Anuar
Dova, María Teresa
Monticelli, Fernando Gabriel
Wahlberg, Hernán Pablo
The ATLAS Collaboration
author_facet Alconada Verzini, María Josefina
Alonso, Francisco
Arduh, Francisco Anuar
Dova, María Teresa
Monticelli, Fernando Gabriel
Wahlberg, Hernán Pablo
The ATLAS Collaboration
author_sort Alconada Verzini, María Josefina
title Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector
title_short Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector
title_full Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector
title_fullStr Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector
title_full_unstemmed Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s = 8 TeV with the ATLAS detector
title_sort search for flavour-changing neutral current top quark decays t → hq in pp collisions at √s = 8 tev with the atlas detector
publishDate 2015
url http://sedici.unlp.edu.ar/handle/10915/86926
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