Observation of a new charmed baryon, testbeam studies for Upgrade-II, and an enhanced analysis experience for the LHCb experiment

Abstract

A search was conducted for excited Ξ꜀⁺ states in the Ξ꜀⁺ π⁺+π⁻ channel using 5.6 fb⁻¹ of pp collisions at √s = 13TeV, collected by the LHCb detector during Run 2 from 2016 to 2018. The following four excited states, with their masses and widths measured, were observed m[Ξ꜀(2815)+] = 2816.65 ± 0.03 (stat) ± 0.03 (syst) ± 0.23(PDG)MeV, Γ[Ξ꜀(2815)⁺] = 2.07 ± 0.08 (stat) ± 0.12 (syst)MeV, m[Ξ꜀(2923)⁺] = 2922.80 ± 0.28 (stat) ± 0.29 (syst) ± 0.23(PDG)MeV, Γ[Ξ꜀(2923)⁺] = 5.3 ± 0.9 (stat) ± 1.2 (syst)MeV, m[Ξ꜀(2970)⁺] = 2968.62 ± 0.46 (stat) ± 0.30 (syst) ± 0.23(PDG)MeV, Γ[Ξ꜀(2970)⁺] = 31.7 ± 1.7 (stat) ± 1.7 (syst)MeV, m[Ξ꜀(3080)⁺] = 3076.77 ± 0.72 (stat) ± 0.11 (syst) ± 0.23(PDG)MeV, Γ[Ξ꜀(3080)⁺] = 6.8 ± 2.3 (stat) ± 0.9 (syst)MeV, where the uncertainties include statistical, systematic, and the PDG [Ξ꜀ mass measurement uncertainty. The Ξ꜀(2923)⁺ state is observed for the first time in any channel, and may be the isospin partner of Ξ꜀(2923)⁰ which was first observed by LHCb in the Λ꜀⁺ K⁻ channel.

A precursor to the MightyPix series, the ATLASPix3.1, was tested at varying irradiation levels during two testbeam campaigns in June and December 2022 at the DESY-II Testbeam Facility, to evaluate the performance of the design and develop testbeam analysis methods for future campaigns. The efficiency and timing performance was evaluated for sensors over a range of fluences and operating temperatures.

A user-friendly interface, LbAPWeb, was created to automatically provide LHCb analysts easy access to additional metrics, tools, and feedback used to validate LHCb production configurations before they are submitted and run at full scale using the Analysis Productions service. Typically, such validations would be carried out manually meaning steps are time-consuming and often skipped by analysts, necessitating re-runs which can be computationally expensive. The user interface and underlying services continue to be developed as the collaboration examines new Run 3 data, as part of the officially recommended Run 3 data processing and analysis workflow.