Erlangen 2026 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 23: Heavy-Ion Collisions and QCD Phases III

HK 23.2: Talk

Wednesday, March 18, 2026, 14:15–14:30, PHIL C 301

Charm-baryon lifetime measurement in pp collisions at √s = 13.6 TeV with ALICE — •Oleksii Lubynets for the ALICE Germany collaboration — Heidelberg university, Physics institute

The lifetimes of heavy-flavour hadrons provide a sensitive benchmark for the heavy-quark expansion (HQE) approach, in which the total decay width is expressed as a power series of heavy-quark mass. Different treatments of higher-order terms can lead to sizable variations in predicted lifetimes, making precise measurements of charm-baryon lifetimes crucial for validating and refining HQE approaches.

We present the implementation of a lifetime measurement for the Λ_c⁺ baryon reconstructed via its decay channel pK⁻π⁺ with data collected at ALICE during Run 3 of the LHC. Charmed hadrons are reconstructed by their decay topology via a Kalman filter algorithm. The measured yield as a function of proper decay time is corrected for detector and reconstruction inefficiencies using dedicated Monte-Carlo simulations implemented with the Geant4 transport model. The effect of feed-down from beauty-hadron decays is corrected in a data-driven way. It allows us to build a corrected proper decay time distribution of prompt Λ_c⁺ from which its lifetime is determined.

The described procedure demonstrates the capability of ALICE to deliver a competitive lifetime measurement of charm baryons, contributing to the global effort to constrain HQE parameters and improve theoretical understanding of charm-hadron decays.

Keywords: heavy-flavor physics; baryon lifetime; complex decay topology reconstruction; ALICE