We report the observation of the bottom, doubly-strange 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 anti-p collisions at s**(1/2) =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 x 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/c2. 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/c2 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 t the Lambda0(b) baryon, we find sigma(Xi-_b) B(Xi-_b --> J/psi Xi-)/sigma (Lambda0(b) B(Lambda0(b) --> J/psi Lambda) 0.167{+0.037}_{-0.025}(stat.) and sigma(Omega-_b) B(Omega-_b --> J/psi Omega-/Sigma(Lambda0(b)) B(Lambda0(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.
Observation of the Omega_b and Measurement of the Properties of the Xi-_b and Omega-_b Baryons
CASTRO, ANDREA;DENINNO, MARIA MADDALENA;MOGGI, NICCOLO';RIMONDI, FRANCO;ZUCCHELLI, STEFANO
2009
Abstract
We report the observation of the bottom, doubly-strange 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 anti-p collisions at s**(1/2) =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 x 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/c2. 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/c2 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 t the Lambda0(b) baryon, we find sigma(Xi-_b) B(Xi-_b --> J/psi Xi-)/sigma (Lambda0(b) B(Lambda0(b) --> J/psi Lambda) 0.167{+0.037}_{-0.025}(stat.) and sigma(Omega-_b) B(Omega-_b --> J/psi Omega-/Sigma(Lambda0(b)) B(Lambda0(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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.