Observation of the Ξ(b)(0) baryon.

Division of High Energy Physics, Department of Physics, University of Helsinki and Helsinki Institute of Physics, FIN-00014, Helsinki, Finland.
Physical Review Letters (Impact Factor: 7.51). 09/2011; 107(10):102001.
Source: PubMed


The observation of the bottom, strange baryon Ξ(b)(0) through the decay chain Ξ(b)(0)→Ξ(c)(+)π-, where ΞΞ(c)(+)→Ξ- π+ π+, Ξ-→Λπ-, and Λ→pπ-, is reported by using data corresponding to an integrated luminosity of 4.2  fb(-1) from pp collisions at square root(s)=1.96  TeV recorded with the Collider Detector at Fermilab. A signal of 25.3(-5.4)(+5.6) candidates is observed whose probability of arising from a background fluctuation is 3.6×10(-12), corresponding to 6.8 gaussian standard deviations. The Ξ(b)(0) mass is measured to be 5787.8±5.0(stat)±1.3(syst)  MeV/c2. In addition, the Ξ(b)- baryon is observed through the process Ξ(b)-→Ξ(c)(0)π-, where Ξ(c)(0)→Ξ- π+, Ξ-→Λπ-, and Λ→pπ-.

Download full-text


Available from: R. Madrak, Jan 21, 2014
15 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The recent observation at CDF and D0 of $\Sigma_b$, $\Sigma^*_b$ and $\Xi_b$ baryons opens the door to the advent of new states in the bottom baryon sector. The states measured provide sufficient constraints to fix the parameters of phenomenological models. One may therefore consistently predict the full bottom baryon spectra. For this purpose we have solved exactly the three-quark problem by means of the Faddeev method in momentum space. We consider our guidance may help experimentalists in the search for new bottom baryons and their findings will help in constraining further the phenomenological models. We identify particular states whose masses may allow to discriminate between the dynamics for the light-quark pairs predicted by different phenomenological models. Within the same framework we also present results for charmed, doubly charmed, and doubly bottom baryons. Our results provide a restricted possible assignment of quantum numbers to recently reported charmed baryon states. Some of them are perfectly described by $D-$wave excitations with $J^P=5/2^+$, as the $\Lambda_c (2880)$, $\Xi_c(3055)$, and $\Xi_c(3123)$.
    European Physical Journal A 08/2008; 37(2). DOI:10.1140/epja/i2008-10616-4 · 2.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The recent observation at the Tevatron of (uub and ddb) baryons within 2 MeV of the predicted Σb-Λb splitting and of baryons at the Tevatron within a few mega electron volts (MeV) of predictions has provided strong confirmation for a theoretical approach based on modeling the color hyperfine interaction. The prediction of = 5790–5800 MeV is reviewed and similar methods used to predict the masses of the excited states and . The main source of uncertainty is the method used to estimate the mass difference mb-mc from known hadrons. We verify that corrections due to the details of the interquark potential and to Ξb– mixing are small. For S-wave qqb states we predict , and . For states with one unit of orbital angular momentum between the b quark and the two light quarks we predict , and . Results are compared with those of other recent approaches.
    Annals of Physics 01/2009; 324(1-324):2-15. DOI:10.1016/j.aop.2008.05.003 · 2.10 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report a measurement of the lifetime of the {Lambda}{sub b}{sup 0} baryon in decays to the {Lambda}{sub c}{sup +}pi{sup -} final state in a sample corresponding to 1.1 fb{sup -1} collected in pp collisions at sq root(s)=1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed {Lambda}{sub b}{sup 0} events we measure {tau}({Lambda}{sub b}{sup 0})=1.401+-0.046(stat)+-0.035(syst) ps (corresponding to c{tau}({Lambda}{sub b}{sup 0})=420.1+-13.7(stat)+-10.6(syst) {mu}m, where c is the speed of light). The ratio of this result and the world average B{sup 0} lifetime yields {tau}({Lambda}{sub b}{sup 0})/tau(B{sup 0})=0.918+-0.038 (stat) and (syst), in good agreement with recent theoretical predictions.
    Physical Review Letters 03/2010; 104(10). DOI:10.1103/PHYSREVLETT.104.102002 · 7.51 Impact Factor