Study of the B<sup>+</sup><sub>c</sub> → J/ψ D<sup>+</sup><sub>s</sub> and B<sup>+</sup><sub>c</sub>→ J/ψ D<sup>*+</sup><sub>s</sub> decays with the ATLAS detector

The decays B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub> and B<sup>+</sup><sub>c</sub>→J/ψD<sup>*+</sup><sub>s</sub> are studied with the ATLAS detector at the LHC using a dataset corresponding...

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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:	2016
Materias:	Ciencias Exactas Física Partículas Elementales ATLAS detector la̵rge hadron collider
Acceso en línea:	http://sedici.unlp.edu.ar/handle/10915/80966
Aporte de:	SEDICI (UNLP) de Universidad Nacional de La Plata

Descripción
Sumario:	The decays B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub> and B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub> are studied with the ATLAS detector at the LHC using a dataset corresponding to integrated luminosities of 4.9 and 20.6 fb<sup>−1</sup> of pp collisions collected at centre-of-mass energies √s=7 TeV and 8 TeV, respectively. Signal candidates are identified through J/ψ→μ+μ− and D<sup>()+</sup><sub>s</sub>→ϕπ+(γ/π<sup>0</sup>) decays. With a two-dimensional likelihood fit involving the B<sup>+</sup><sub>c</sub> reconstructed invariant mass and an angle between the μ+ and D<sup>+</sup><sub>s</sub> candidate momenta in the muon pair rest frame, the yields of B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub> and B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub>, and the transverse polarisation fraction in B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub> decay are measured. The transverse polarisation fraction is determined to be Γ±±(B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub>)/Γ(B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub>)=0.38±0.23±0.07, and the derived ratio of the branching fractions of the two modes is B<sub>B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub></sub>/B<sub>B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub></sub>=2.8+1.2−0.8±0.3 , where the first error is statistical and the second is systematic. Finally, a sample of B<sup>+</sup><sub>c</sub>→J/ψπ+ decays is used to derive the ratios of branching fractions BB<sub>B<sup>+</sup><sub>c</sub>→J/ψD<sup>+</sup><sub>s</sub></sub>/B<sub>B<sup>+</sup><sub>c</sub>→J/ψπ+</sub>=3.8±1.1±0.4±0.2 and B<sub>B<sup>+</sup><sub>c</sub>→J/ψD<sup>*+</sup><sub>s</sub></sub>/B<sub>B<sup>+</sup><sub>c</sub>→J/ψπ+</sub>=10.4±3.1±1.5±0.6, where the third error corresponds to the uncertainty of the branching fraction of D<sup>+</sup><sub>s</sub>→ϕ(K+K−)π+ decay. The available theoretical predictions are generally consistent with the measurement.