Observation of the Ωb- baryon and measurement of the properties of the Ξb- and Ωb- baryons

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Aaltonen , T , Mehtala , P , Orava , R , Maki , T , Saarikko , H , Osterberg , K & CDF collaboration 2009 , ' Observation of the Ωb- baryon and measurement of the properties of the Ξb- and Ωb- baryons ' Physical Review D : Particles, Fields, Gravitation and Cosmology , vol 80 , no. 7 , pp. 072003 . , 10.1103/PhysRevD.80.072003

Title: Observation of the Ωb- baryon and measurement of the properties of the Ξb- and Ωb- baryons
Author: Aaltonen, Timo; Mehtala, P.; Orava, R.; Maki, T.; Saarikko, H.; Osterberg, K.; CDF collaboration
Contributor: University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Helsinki Institute of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
Belongs to series: Physical Review D : Particles, Fields, Gravitation and Cosmology
ISSN: 1550-7998
Abstract: We report the observation of the bottom, doubly-strange baryon Omega^-_b through the decay chain Omega^-_b -> J/psi Omega^-, where J/psi -> mu^+ mu^-, Omega^- -> Lambda K^-, and Lambda -> p pi^-, using 4.2 fb^{-1} of data from p\bar p collisions at sqrt{s}=1.96 TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0 * 10^{-8}, or 5.5 Gaussian standard deviations. The Omega^-_b mass is measured to be 6054.4 +/- 6.8 (stat.) +/- 0.9 (syst.) MeV/c^2. The lifetime of the Omega^-_b baryon is measured to be 1.13^{+0.53}_{-0.40}(stat.) +/- 0.02(syst.)$ ps. In addition, for the \Xi^-_b baryon we measure a mass of 5790.9 +/- 2.6(stat.) +/- 0.8(syst.) MeV/c^2 and a lifetime of 1.56^{+0.27}_{-0.25}(stat.) +/-0.02(syst.) ps. Under the assumption that the \Xi_b^- and \Omega_b^- are produced with similar kinematic distributions to the \Lambda^0_b baryon, we find sigma(Xi_b^-) B(Xi_b^- -> J/psi Xi^-)}/ sigma(Lambda^0_b) B(Lambda^0_b -> J/psi Lambda)} = 0.167^{+0.037}_{-0.025}(stat.) +/-0.012(syst.) and sigma(Omega_b^-) B(Omega_b^- -> J/psi Omega^-)/ sigma(Lambda^0_b) B(Lambda^0_b -> J/psi Lambda)} = 0.045^{+0.017}_{-0.012}(stat.) +/- 0.004(syst.) for baryons produced with transverse momentum in the range of 6-20 GeV/c.
Peer review status: Peer reviewed
URI: http://hdl.handle.net/10138/24454
Date: 2009
Subject: 114 Physical sciences
hep-ex


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