Search for new light gauge bosons in Higgs boson decays to four-lepton final states in pp collisions at √s = 8 TeV with the ATLAS detector at the LHC

This paper presents a search for Higgs bosons decaying to four leptons, either electrons or muons, via one or two light exotic gauge bosons Z<sub>d</sub>, H→ZZ<sub>d</sub>→4ℓ or H→Z<sub>d</sub>Z<sub>d</sub>→4ℓ. The search was performed using pp collisi...

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Detalles Bibliográficos
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 proton-proton collisions ATLAS detector
Acceso en línea:	http://sedici.unlp.edu.ar/handle/10915/86910
Aporte de:	SEDICI (UNLP) de Universidad Nacional de La Plata

Descripción
Sumario:	This paper presents a search for Higgs bosons decaying to four leptons, either electrons or muons, via one or two light exotic gauge bosons Z<sub>d</sub>, H→ZZ<sub>d</sub>→4ℓ or H→Z<sub>d</sub>Z<sub>d</sub>→4ℓ. The search was performed using pp collision data corresponding to an integrated luminosity of about 20 fb<sup>-1</sup> at the center-of-mass energy of √s = 8 TeV recorded with the ATLAS detector at the Large Hadron Collider. The observed data are well described by the Standard Model prediction. Upper bounds on the branching ratio of H→ZZ<sub>d</sub>→4ℓ and on the kinetic mixing parameter between the Z<sub>d</sub> and the Standard Model hypercharge gauge boson are set in the range (1-9)×10<sup>-5</sup> and (4-17)×10-2 respectively, at 95% confidence level assuming the Standard Model branching ratio of H→ZZ*→4ℓ, for Z<sub>d</sub> masses between 15 and 55 GeV. Upper bounds on the effective mass mixing parameter between the Z and the Z<sub>d</sub> are also set using the branching ratio limits in the H→ZZ<sub>d</sub>→4ℓ search, and are in the range (1.5-8.7)×10<sup>-4</sup> for 15<m<SUB>Z<sub>d</sub></SUB><35 GeV. Upper bounds on the branching ratio of H→Z<sub>d</sub>Z<sub>d</sub>→4ℓ and on the Higgs portal coupling parameter, controlling the strength of the coupling of the Higgs boson to dark vector bosons are set in the range (2-3)×10<sup>-5</sup> and (1-10)×10<sup>-4</sup> respectively, at 95% confidence level assuming the Standard Model Higgs boson production cross sections, for Z<sub>d</sub> masses between 15 and 60 GeV.