Observation of the doubly strange b baryon Omega_b-

TL;DR

This paper reports the first observation of the doubly strange b baryon Omega_b- in proton-antiproton collisions, measuring its mass and establishing its existence with high statistical significance.

Contribution

The study provides the first experimental evidence of the Omega_b- baryon, including its mass measurement and significance level, using data from the Fermilab Tevatron Collider.

Findings

Omega_b- mass measured at 6.165 GeV

Signal significance of 5.4 sigma

Observation based on 17.8 signal events

Abstract

We report the observation of the doubly strange b baryon Omega_b- in the decay channel Omega_b- to J/psi Omega-, with J/psi to mu+ mu- and Omega- to Lambda K-, in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV. Using approximately 1.3 fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron Collider, we observe 17.8 +/- 4.9 (stat) +/- 0.8 (syst) Omega_b- signal events at a mass of 6.165 +/- 0.010 (stat) +/- 0.013(syst.) GeV. The significance of the observed signal is 5.4 sigma, corresponding to a probability of 6.7 x 10^{-8} of it arising from a background fluctuation.