We present the first observation of the weak decay Ξ−b → Λ0b π−, which is mediated by an s → u ̄ud transitionwithin the Ξ_b^- baryon. The analysis uses a pp collision data sample at a center-of-mass energy of 13 TeV corresponding to 5.5 fb^(−1) of integrated luminosity. The sample of Λb0 baryons used in this analysis are reconstructed through their decays to Λ+c π− and Λ+c π−π+π−. From a fit to the Ξ−b → Λ0b π− mass spectrum, the Ξ−b → Λ0b π− decay is observed with a significance of 11.3 standard deviations, thus establishing observation of this decay. The relative branching fraction is measured to be f(Ξ−b)/f(Λ0b)*B(Ξ−b → Λ0b π−) = (6.35 ± 0.70 ± 0.47) × 10^(−4), where f(Ξ−b) and f(Λ0b) are the fragmentation fractions, and B(Ξ−b → Λ0b π−) is the branching fraction, and the uncertainties are statistical and experimental systematic. Using the measured value of f(Ξ−b)/f(Λ0b)= (8.2 ± 0.7 ± 0.6 ± 2.5) × 10^(−2), the branching fraction is measured as B(Ξ−b → Λ0b π−) = (0.77 ± 0.11 ± 0.07 ± 0.23) × 10^(−2). For predictions of Ξ−b decay width that only considers b-quark decay, this contribution must be added, thus increasing predictions of the Ξ−b decay width by about 1%","abstract_html":"<p>We present the first observation of the weak decay Ξ−b → Λ0b π−, which is mediated by an s → u ̄ud transitionwithin the Ξ_b^- baryon. The analysis uses a pp collision data sample at a center-of-mass energy of 13 TeV corresponding to 5.5 fb^(−1) of integrated luminosity. The sample of Λb0 baryons used in this analysis are reconstructed through their decays to Λ+c π− and Λ+c π−π+π−. From a fit to the Ξ−b → Λ0b π− mass spectrum, the Ξ−b → Λ0b π− decay is observed with a significance of 11.3 standard deviations, thus establishing observation of this decay. The relative branching fraction is measured to be f(Ξ−b)/f(Λ0b)*B(Ξ−b → Λ0b π−) = (6.35 ± 0.70 ± 0.47) × 10^(−4), where f(Ξ−b) and f(Λ0b) are the fragmentation fractions, and B(Ξ−b → Λ0b π−) is the branching fraction, and the uncertainties are statistical and experimental systematic. Using the measured value of f(Ξ−b)/f(Λ0b)= (8.2 ± 0.7 ± 0.6 ± 2.5) × 10^(−2), the branching fraction is measured as B(Ξ−b → Λ0b π−) = (0.77 ± 0.11 ± 0.07 ± 0.23) × 10^(−2). For predictions of Ξ−b decay width that only considers b-quark decay, this contribution must be added, thus increasing predictions of the Ξ−b decay width by about 1%","abstract_has_math":false,"creators":["Li, Zhuoming"],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Blusk, Steven"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-12-14T08:00:00Z","date_published":"2022-12-14T08:00:00Z","updated_at":"2026-07-24T04:56:23Z","subjects":["Physics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://surface.syr.edu/etd/1589","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Blusk, Steven"]},{"key":"dc:creator","label":"Author","values":["Li, Zhuoming"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://surface.syr.edu/etd/1589"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["
We present the first observation of the weak decay Ξ−b → Λ0b π−, which is mediated by an s → u ̄ud transitionwithin the Ξ_b^- baryon. The analysis uses a pp collision data sample at a center-of-mass energy of 13 TeV corresponding to 5.5 fb^(−1) of integrated luminosity. The sample of Λb0 baryons used in this analysis are reconstructed through their decays to Λ+c π− and Λ+c π−π+π−. From a fit to the Ξ−b → Λ0b π− mass spectrum, the Ξ−b → Λ0b π− decay is observed with a significance of 11.3 standard deviations, thus establishing observation of this decay. The relative branching fraction is measured to be f(Ξ−b)/f(Λ0b)*B(Ξ−b → Λ0b π−) = (6.35 ± 0.70 ± 0.47) × 10^(−4), where f(Ξ−b) and f(Λ0b) are the fragmentation fractions, and B(Ξ−b → Λ0b π−) is the branching fraction, and the uncertainties are statistical and experimental systematic. Using the measured value of f(Ξ−b)/f(Λ0b)= (8.2 ± 0.7 ± 0.6 ± 2.5) × 10^(−2), the branching fraction is measured as B(Ξ−b → Λ0b π−) = (0.77 ± 0.11 ± 0.07 ± 0.23) × 10^(−2). For predictions of Ξ−b decay width that only considers b-quark decay, this contribution must be added, thus increasing predictions of the Ξ−b decay width by about 1%"]},{"key":"dc:title","label":"Title","values":["Observation of the Ξ_b^-→Λ_b^0 π^- decay and measurement of B(Ξ_b^-→Λ_b^0 π^-)"]}]}],"canonical_facts":{"dc:contributor":["Blusk, Steven"],"dc:creator":["Li, Zhuoming"],"dc:description.abstract":["
We present the first observation of the weak decay Ξ−b → Λ0b π−, which is mediated by an s → u ̄ud transitionwithin the Ξ_b^- baryon. The analysis uses a pp collision data sample at a center-of-mass energy of 13 TeV corresponding to 5.5 fb^(−1) of integrated luminosity. The sample of Λb0 baryons used in this analysis are reconstructed through their decays to Λ+c π− and Λ+c π−π+π−. From a fit to the Ξ−b → Λ0b π− mass spectrum, the Ξ−b → Λ0b π− decay is observed with a significance of 11.3 standard deviations, thus establishing observation of this decay. The relative branching fraction is measured to be f(Ξ−b)/f(Λ0b)*B(Ξ−b → Λ0b π−) = (6.35 ± 0.70 ± 0.47) × 10^(−4), where f(Ξ−b) and f(Λ0b) are the fragmentation fractions, and B(Ξ−b → Λ0b π−) is the branching fraction, and the uncertainties are statistical and experimental systematic. Using the measured value of f(Ξ−b)/f(Λ0b)= (8.2 ± 0.7 ± 0.6 ± 2.5) × 10^(−2), the branching fraction is measured as B(Ξ−b → Λ0b π−) = (0.77 ± 0.11 ± 0.07 ± 0.23) × 10^(−2). For predictions of Ξ−b decay width that only considers b-quark decay, this contribution must be added, thus increasing predictions of the Ξ−b decay width by about 1%"],"dc:identifier":["https://surface.syr.edu/etd/1589"],"dc:subject":["Physics"],"dc:title":["Observation of the Ξ_b^-→Λ_b^0 π^- decay and measurement of B(Ξ_b^-→Λ_b^0 π^-)"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T04:56:23Z"}