Measurement of the parity-violating asymmetry parameter αb and the helicity amplitudes for the decay Λ<sup>0</sup>b →j /ψ Λ<sup>0</sup> with the ATLAS detector

A measurement of the parity-violating decay asymmetry parameter, αb, and the helicity amplitudes for the decay Λ<sup>0</sup>b→J/ψ(μ+μ-)Λ<sup>0</sup>(pπ-) is reported. The analysis is based on 1400 Λ<sup>0</sup>b and Λ<sup>0</sup>¯b baryons selected in...

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Detalles Bibliográficos
Autores principales:	Alconada Verzini, María Josefina, Alonso, Francisco, Anduaga, Xabier Sebastián, Dova, María Teresa, Monticelli, Fernando Gabriel, Tripiana, Martín Fernando, The ATLAS Collaboration
Formato:	Articulo
Lenguaje:	Inglés
Publicado:	2014
Materias:	Física Ciencias Exactas Parity-violating asymmetry ATLAS detector Quantum chromodynamics
Acceso en línea:	http://sedici.unlp.edu.ar/handle/10915/85215
Aporte de:	SEDICI (UNLP) de Universidad Nacional de La Plata

Descripción
Sumario:	A measurement of the parity-violating decay asymmetry parameter, αb, and the helicity amplitudes for the decay Λ<sup>0</sup>b→J/ψ(μ+μ-)Λ<sup>0</sup>(pπ-) is reported. The analysis is based on 1400 Λ<sup>0</sup>b and Λ<sup>0</sup>¯b baryons selected in 4.6 fb-1 of proton-proton collision data with a center-of-mass energy of 7 TeV recorded by the ATLAS experiment at the LHC. By combining the Λb0 and Λ<sup>0</sup>¯b samples under the assumption of CP conservation, the value of αb is measured to be 0.30±0.16(stat)±0.06(syst). This measurement provides a test of theoretical models based on perturbative QCD or heavy-quark effective theory.