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| CMS-BPH-12-001 ; CERN-PH-EP-2012-118 | ||
| Observation of a New $\Xi_{b}$ Baryon | ||
| CMS Collaboration | ||
| 27 April 2012 | ||
| Phys. Rev. Lett. 108 (2012) 252002 | ||
| Abstract: The observation of a new b baryon via its strong decay into $\Xi_{b}^- \pi^+$ (plus charge conjugates) is reported. The measurement uses a data sample of pp collisions at $\sqrt{s}$ = 7 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 5.3 inverse femtobarns. The known $\Xi_b^-$ baryon is reconstructed via the decay chain $\Xi_{b}^- \to J/\psi \Xi^- \to \mu^+ \mu^- \Lambda^0 \pi^-$, with $\Lambda^0 \to p \pi^-$. A peak is observed in the distribution of the difference between the mass of the $\Xi_{b}^- \pi^+$ system and the sum of the masses of the $\Xi_{b}^-$ and $\pi^+$, with a significance exceeding five standard deviations. The mass difference of the peak is 14.84 +/- 0.74 (stat.) +/- 0.28 (syst.) MeV. The new state most likely corresponds to the $J^P=3/2^+$ companion of the $\Xi_b$. | ||
| Links: e-print arXiv:1204.5955 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; Public twiki page ; CADI line (restricted) ; | ||
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Compact Muon Solenoid LHC, CERN |
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