# Observation and mass measurement of the baryon $Xi_b^-$

We report the observation and measurement of the mass of the bottom, strange baryon Xib- through the decay chain Xib--->J/psiXi-, where J/psi-->µ+µ-, Xi--->Lambdapi-, and Lambda-->ppi-. A signal is observed whose probability of arising from a background fluctuation is 6.6{\AA}~10-15, or 7.7 Gaussian standard deviations. The Xib- mass is measured to be 5792.9$\pm$2.5(stat) $\pm$1.7(syst) MeV/c2.

### Cited Authors

• Aaltonen, ; T, ; others,

• 2007

### Published In

• Phys. Rev. Lett.

• 99 /

• 052002 -

• 17930745