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Measurement of Lamba(b) polarization and angular parameters in Lambda(b) to Jpsi Lambda decays from pp collisions at sqrt(s) = 7 and 8 TeV

The c and b quarks have masses significantly above of the $\Lambda_{\text{QCD}}$ QCD scale, and therefore their production and treatment should be perturbatively calculable. There are many common implementations taking these ideas, the most common QCD factorization (QCDF), perturbative QCD (pQCD), h...

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Detalles Bibliográficos
Autor principal: Reyes Almanza, Rogelio
Lenguaje:eng
Publicado: 2018
Materias:
Acceso en línea:http://cds.cern.ch/record/2648543
Descripción
Sumario:The c and b quarks have masses significantly above of the $\Lambda_{\text{QCD}}$ QCD scale, and therefore their production and treatment should be perturbatively calculable. There are many common implementations taking these ideas, the most common QCD factorization (QCDF), perturbative QCD (pQCD), heavy-quark-effective theory (HQET). The assumption heavy quarks remain quark information rather hadronization has support under the heavy quark approach. In this work, an analysis of the bottom baryon decay $\Lambda_\text{b}\to J/\psi\Lambda$ is performed to measure the $\Lambda_\text{b}$ polarization and three angular parameters in data from pp collisions at $\sqrt{s} = 7$ and 8\TeV, collected by the CMS experiment at the LHC. The $\Lambda_\text{b}$ polarization is measured to be $0.00 \pm 0.06$ (stat) $\pm 0.06$ (syst) and the parity-violating asymmetry parameter is determined to be $0.14 \pm 0.14$ (stat) $\pm 0.10$ (syst). The measurements are compared to various theoretical predictions, including those from perturbative quantum chromodynamics.