Observation of excited Ω⁰꜀ states, and commissioning of the RICH detector

Abstract

The first observation of the Ω⁻b → Ξ⁺꜀ K⁻π⁻ decay is reported using pp collision data at centre-of-mass energies of 7, 8 and 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb⁻¹. The excited Ω꜀**⁰ states are studied in the Ξ⁺꜀ K⁻ mass projection of the Ω⁻b → Ξ⁺꜀ K⁻π⁻ decays.

Four states are observed:

M(Ω꜀(3000)⁰) = 2999.2 ± 0.9 (stat) ± 0.9(syst) MeV/c², Γ(Ω꜀(3000)⁰) = 4.8 ± 2.1 (stat) ± 2.5 (syst) MeV,

M(Ω꜀(3050)⁰ = 3050.1 ± 0.3 (stat) ± 0.2 (syst) MeV/c², Γ(Ω꜀(3050)⁰ < 1.6 MeV, 95% CL,

M(Ω꜀(3065)⁰) = 3065.9 ± 0.4 (stat) ± 0.4(syst) MeV/c², Γ(Ω꜀(3065)⁰) = 1.7 ± 1.0 (stat) ± 0.5 (syst) MeV,

M(Ω꜀(3090)⁰ = 3091.0 ± 1.1 (stat) ± 1.0 (syst) MeV/c², Γ(Ω꜀(3090)⁰ < 7.4 ± 3.1 (stat) ± 2.8 (syst) MeV,

where the uncertainties are statistical and systematic, respectively. Each resonance has a significance larger than 6 standard deviations. This thesis will also summarise the work completed for the ring imaging Cherenkov detectors, including laboratory work for the commissioning of the detectors and the analysis of the signal induced noise for the multi-anode photomultiplier tubes.