Observation of an Excited Ω^{-} Baryon

Area of Science:

• Particle Physics
• Hadron Spectroscopy
• Experimental Nuclear Physics

Background:

• Hyperons are baryons containing strange quarks.
• Excited states of hyperons provide insights into the strong nuclear force.
• The Belle detector has collected extensive data on particle decays.

Purpose of the Study:

• To report the observation of a new excited hyperon state.
• To characterize the properties of this new particle, including its mass and width.
• To investigate its production mechanism in ϒ decays.

Main Methods:

• Analysis of data collected by the Belle detector.
• Identification of decay channels Ξ^{0}K^{-} and Ξ^{-}K_{S}^{0}.
• Measurement of the invariant mass and decay width of the candidate particle.

Main Results:

• Observation of a new Ω^{*-} hyperon candidate.
• Measured mass: 2012.4±0.7(stat)±0.6(syst) MeV/c^{2}.
• Measured width: Γ=6.4_{-2.0}^{+2.5}(stat)±1.6(syst) MeV.
• The Ω^{*-} is predominantly observed in ϒ(1S), ϒ(2S), and ϒ(3S) decays.

Conclusions:

• The discovery of this new Ω^{*-} state expands the known spectrum of hyperons.
• Its observation in ϒ decays suggests specific production mechanisms.
• Further studies are needed to confirm its quantum numbers and explore its properties.