Core Concepts
Decays of Ξ⁻ᵇ and Ω⁻ᵇ baryons to Λ⁺ₓ h⁻ h'⁻ final states, with h⁻ h'⁻ being π⁻ π⁻, K⁻ π⁻ and K⁻ K⁻ meson pairs, are observed and their branching fractions measured relative to the B⁻ → Λ⁺ₓ pπ⁻ mode. The Ξ⁻ᵇ production asymmetry is also measured.
Abstract
This analysis searches for decays of Ξ⁻ᵇ and Ω⁻ᵇ baryons to Λ⁺ₓ h⁻ h'⁻ final states, where h⁻ and h'⁻ are K⁻ or π⁻ mesons. The data sample corresponds to an integrated luminosity of 8.7 fb⁻¹ of pp collisions collected with the LHCb detector.
Key highlights:
- Ξ⁻ᵇ → Λ⁺ₓ K⁻ π⁻, Ξ⁻ᵇ → Λ⁺ₓ K⁻ K⁻ and Ω⁻ᵇ → Λ⁺ₓ K⁻ K⁻ decays are observed with over 5σ significance.
- The product of the relative branching fractions and fragmentation fractions for each signal mode are measured, using the B⁻ → Λ⁺ₓ pπ⁻ mode as a control channel.
- The Ξ⁻ᵇ production asymmetry is measured and found to be consistent with zero.
- The previously unobserved B⁻ → Λ⁺ₓ pK⁻ decay is also observed and its branching fraction measured relative to B⁻ → Λ⁺ₓ pπ⁻.
The analysis uses a blind approach for the Ξ⁻ᵇ and Ω⁻ᵇ baryon decays, with the signal mass regions not inspected until the analysis procedures are established. Efficiency corrections accounting for detector effects and phase-space distributions are applied, and various systematic uncertainties are evaluated.
Stats
The Ξ⁻ᵇ → Λ⁺ₓ K⁻ π⁻ mode is used to measure the Ξ⁻ᵇ production asymmetry, which is found to be consistent with zero.
The B⁻ → Λ⁺ₓ pK⁻ decay is observed for the first time.
Quotes
"Decays of Ξ⁻ᵇ and Ω⁻ᵇ baryons to Λ⁺ₓ h⁻ h'⁻ final states, with h⁻ h'⁻ being π⁻ π⁻, K⁻ π⁻ and K⁻ K⁻ meson pairs, are searched for using data collected with the LHCb detector."
"The Ξ⁻ᵇ → Λ⁺ₓ K⁻ π⁻ mode is also used to measure the Ξ⁻ᵇ production asymmetry, which is found to be consistent with zero."
"The B⁻ → Λ⁺ₓ pK⁻ decay is observed for the first time, and its branching fraction is measured relative to that of the B⁻ → Λ⁺ₓ pπ⁻ mode."