/ hep-ex CERN-PH-EP-2014-034

Measurement of the parity-violating asymmetry parameter $\alpha_b$ and the helicity amplitudes for the decay $\Lambda_b \to J/\psi+\Lambda$ with the ATLAS detector

Pages: 12

Abstract: A measurement of the parity-violating decay asymmetry parameter, $\alpha_b$, and the helicity amplitudes for the decay $\Lambda_b^0\to J/\psi(\mu^+\mu^-) \Lambda^0 (p\pi^-)$ is reported. The analysis is based on 1400 $\Lambda_b^0$ and $\bar{\Lambda}_b^0$ baryons selected in $4.6~\rm{fb}^{-1}$ 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 $\Lambda_b^0$ and $\bar{\Lambda}_b^0$ samples under the assumption of $CP$ conservation, the value of $\alpha_b$ is measured to be $0.30 \pm 0.16 ({\rm stat})\pm 0.06 ({\rm syst})$. This measurement provides a test of theoretical models based on perturbative QCD or heavy-quark effective theory.

Note: 12 pages plus author list (25 pages total), 6 figures, 6 tables, submitted to Physical Review D, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/BPHY-2013-03/

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Запись создана 2014-05-06, последняя модификация 2014-05-06

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